JPH043591Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inverter-type DC power supply device that is used with two types of AC power sources, high voltage and low voltage.

[Conventional technology]

Generally, an inverter-type DC power supply device used as a power supply device for a DC arc welding machine or a DC arc discharge lamp is configured as shown in FIG.

In the same figure, 1a and 1b are high voltage (200V),
A pair of terminals 2a and 2b that are selectively connected to two types of low voltage (100V) AC power sources are interlocking air circuit breakers with one end connected to the terminals 1a and 1b, respectively.

3 is a bridge rectifier circuit, 3a is a first rectifying diode whose anode is connected to the other end of the circuit breaker 2a, 3b is a second rectifying diode whose cathode is connected to the other end of the circuit breaker 2a, 3c is an anode, The cathode is the other end of the circuit breaker 2b, and the first diode 3a
A third rectifying diode, 3d, is an anode connected to the cathodes of the second diode 3b, and a fourth rectifying diode whose cathode is connected to the anode of the second diode 3b and the third diode 3c, respectively.

4 is a series circuit of two smoothing capacitors 4a and 4b, and both ends of the series circuit 4 are connected to the cathode of the first diode 3a and the anode of the second diode 3b, respectively.

5 is a rectification type changeover switch in which a low voltage contact 5a is connected to the connection point of capacitors 4a and 4b and a high voltage contact 5b is opened, and a changeover piece 5c is connected to the connection point of the circuit breaker 2b
connected to the other end.

6a is a first switching element for an inverter having an NPN transistor configuration whose collector is connected to the cathode of the first diode 3a; 6b is a collector;
This is a second switching element for an inverter having an NPN transistor configuration, the emitter of which is connected to the emitter of the first switching element 6a and the anode of the second diode 3b.

Reference numeral 7 denotes an output transformer in which both ends of a primary winding 7a are connected to the emitter of the first switching element 6a and the connection points of the capacitors 4a and 4b, respectively.The switching elements 6a, 6b and the transformer 7 constitute a high frequency inverter 8. Ru.

Reference numeral 9 designates a control power source changeover switch having a low voltage contact 9a and a high voltage contact 9b, and a changeover piece 9c connected to the other end of the circuit breaker 2a, and is switched in conjunction with the changeover switch 5. 10 is an auxiliary transformer in which both ends of the primary winding 10a are connected to the high voltage contact 9b and the other end of the circuit breaker 2b, and an intermediate tap of the primary winding 10a is connected to the high voltage contact 9b and the other end of the circuit breaker 2b.
ta is connected to the low voltage contact 9a.

Reference numeral 11 denotes a drive circuit in which three input terminals are connected to both ends of the secondary winding 10b of the auxiliary transformer 10 and to the intermediate tap tb, respectively, and two output terminals are connected to the bases serving as control terminals of the switching elements 6a and 6b, respectively, in reverse phase. A high frequency switching signal is outputted to control the output of the inverter 8.

12a and 12b are fifth and sixth rectifying diodes whose anodes are connected to both ends of the secondary winding 7b of the output transformer 7, respectively, and whose cathodes are connected to each other, forming an output rectifying circuit 12 for full-wave rectification. do.

13 is a smoothing reactor whose one end is connected to the cathode of the diode 12a, 14a and 14b are the other ends of the reactor 13, and the secondary winding 7 of the output transformer 7.
There are two output terminals connected to each intermediate tap t of b, and a welding load is connected between both output terminals 14a and 14b.

If the AC power source is a low voltage of 100V,
When the changeover switches 5 and 9 are switched to the low voltage contacts 5a and 9a to set a low voltage according to the voltage of the AC power supply, the changeover switch 5 switches the capacitors 4a and 4
The connection between the connection point b and the anode of the third diode 3c is closed, and the first and second diodes 3a, 3
A voltage doubler rectifier circuit is formed by capacitors 4a, 4b, and changeover switch 5, and a DC voltage of approximately 200V, which is doubled, is generated between both ends of the series circuit 4 based on voltage doubler rectification of the AC power supply voltage of 100V.

Furthermore, the switching elements 6a and 6b perform high frequency switching in opposite phases according to a switching signal from the drive circuit 11, and this switching converts the DC voltage into a high frequency output.

This high frequency output is supplied to the output rectifier circuit 12 via the output transformer 7.
Sixth diode 12a, 12b and reactor 1
3, the high frequency output is rectified and smoothed, and a predetermined DC welding voltage is applied to the welding load between the output terminals 14a and 14b.

Next, when the AC power supply is a high voltage of 200V, when the changeover switches 5 and 9 are switched to the high voltage contacts 5b and 9b to set the high voltage according to the voltage of the AC power supply, the changeover switch 5 switches the capacitors 4a and 4b.
The connection point between the connection point and the anode of the third diode 3c is opened, and the first to fourth diodes 3a to 3
b. A full-wave rectifier circuit is formed by the capacitors 4a and 4b, and at this time, based on the full-wave rectification of the AC power supply voltage of 200V, between both ends of the series circuit 4,
A DC voltage of approximately 200V is generated, similar to when a 100V AC power supply is input.

Then, the switching elements 6a and 6b are high-frequency switched in opposite phases by a switching signal from the drive circuit 11, and the DC voltage is converted to a high-frequency output, and the high-frequency output via the output transformer 7 is rectified by the output rectifier circuit 12 and the reactor 13. , smoothed.

Therefore, substantially the same welding voltage as when the 100V AC power source is input is applied to the welding load between the output terminals 14a and 14b.

In addition, the changeover switch 9 is switched in conjunction with the changeover switch 5, and the primary winding 10 of the auxiliary transformer 10 is
The number of turns of a becomes 1/2 when inputting 100V AC power when inputting 200V AC power.

Therefore, the primary winding 10a of the auxiliary transformer 10
When the input voltage is 100V, the turns ratio of the secondary winding 10b is twice that when the input voltage is 200V, and the auxiliary transformer 1
The voltage across the secondary winding 10b of
It remains constant regardless of 100V or 200V, and the drive circuit 11
The input voltage is held constant regardless of the AC power supply voltage of 100V or 200V, and it operates stably. Due to this stable operation, the switching signals to the switching elements 6a and 6b remain constant regardless of the AC power supply voltage, and the AC Regardless of whether the power source is 100V or 200V, the output voltage of the inverter 8 is controlled to the same value.

[The problem that the idea aims to solve]

In the case of the conventional DC power supply device shown in FIG.
There is a problem that when the voltage is as high as 200V, the rectifier circuit 3, capacitors 4a and 4b, and switching elements 6a and 6b are damaged by the abnormally high voltage.

That is, even though the AC power supply has a high voltage of 200V, when the voltage is set to a low voltage and the selector switch 5 is switched to the low voltage contact 5a, the setting state is maintained and the operation continues, so that the first and second Due to the voltage doubler rectifier circuit of diodes 3a, 3b, capacitors 4a, 4b, and changeover switch 5, an extremely high DC voltage of approximately 400V is generated across the series circuit 4.
This high DC voltage damages the diodes 3a to 3d, capacitors 4a and 4b, and switching elements 6a and 6b of the rectifier circuit 3.

The present invention is based on a voltage setting error of the device with respect to the voltage of the AC power supply.
b and switching elements 6a, 6 for the inverter
An object of the present invention is to provide a DC power supply device that prevents damage to the device.

[Means to solve the problem]

In order to achieve the above object, the DC power supply device of the present invention can be selectively connected to two types of AC power sources, high voltage and low voltage, as shown in FIG. 1, which corresponds to one embodiment. A pair of terminals 1a, 1b
A first rectifying diode 3a of the bridge rectifier circuit 3 whose anode is connected to the terminal 1a, and a second rectifying diode 3b of the rectifier circuit 3 whose cathode is connected to the anode of the first diode 3a.
and a third rectifying diode 3c of the rectifier circuit 3 whose cathode and anode are connected to the cathode and terminal 1b of the first diode 3a, respectively, and whose cathode and anode are connected to the anodes of the third diode 3c and the second diode 3b, respectively. a fourth rectifying diode 3d of the rectifier circuit 3, a series circuit 4 of two smoothing capacitors 4a and 4b provided between the cathode of the first diode 3a and the anode of the second diode 3b, and both capacitors. A rectification method selector switch 5 that closes or opens between the connection point of 4a and 4b and the anode of the third diode 3c depending on the high voltage setting or low voltage setting.
and two inverter switching elements 6a and 6b which are connected in series between both ends of the series circuit 4 and perform high frequency switching in opposite phases, and both switching elements 6 are connected to both ends of the primary winding 7a.
an output transformer 7 connected to the connection point of a and 6b and the connection point of both capacitors 4a and 4b, an output rectifier circuit 12 connected to the secondary winding 7b of the transformer 7, and a terminal 1a and the first diode 3a. A normally open cutoff relay contact 20 provided between the anode of and a control device 21 that closes the relay contact 20 only when the relay contact 20 is closed.

[Effect]

In the case of the DC power supply device of the present invention configured as described above, when the AC power supply is at a low voltage and the device is correctly set to a low voltage, the changeover switch 5 and the relay contact 20 are closed.

A voltage doubler rectifier circuit is formed by the first and second diodes 3a, 3b, capacitors 4a, 4b, and changeover switch 5, and this circuit allows a normal voltage of approximately twice the voltage of the AC power supply to be applied between both ends of the series circuit 4. DC voltage is generated.

Further, when the AC power source is at a high voltage twice as high as the low voltage and the device is correctly set to a high voltage, the changeover switch 5 is opened and the relay contact 20 is closed.

And each diode 3a-3 of the rectifier circuit 3
d, a full-wave rectifier circuit is formed by the capacitors 4a and 4b, and this circuit generates a normal DC voltage almost the same as that at the low voltage setting across the series circuit 4.

Furthermore, when the voltage of the device is set correctly, the DC voltage across the series circuit 4 is converted into a high frequency output by high frequency switching of the switching elements 6a and 6b, and this high frequency output is transmitted to the output transformer 7.
is supplied to the output rectifier circuit 12 via.

Then, the high frequency output is converted into direct current by the output rectifier circuit 12, and direct current of a predetermined voltage is output from the device regardless of the low voltage or high voltage of the alternating current voltage.

On the other hand, a voltage setting error may occur in the device, and the switch 5 may be opened to form a full-wave rectifier circuit when the AC power supply is at a low voltage, or the switch 5 may be closed when the AC power supply is at a high voltage. When a voltage doubler rectifier circuit is formed, the control device 21 does not close the relay contact 20, the relay contact 20 is held open, and AC power is no longer supplied to the rectifier circuit 3.
In particular, when the AC power supply is at a high voltage and a voltage doubler rectifier circuit is formed, an abnormal high voltage DC that is twice the normal voltage based on the voltage doubler rectifier is not generated across the series circuit 4, and the rectifier circuit 3 Each diode 3a to 3d,
Capacitors 4a, 4b, switching element 6a,
6b is prevented from being damaged by high voltage.

〔Example〕

Next, the present invention will be described in the first part showing one embodiment thereof.
This will be explained with reference to FIG.

In FIG. 1, the same reference numerals as in FIG. 3 indicate the same or equivalent parts, and 15 is a safety switch that can be opened and closed by closing and opening the lid of the case that houses the control changeover switch and changeover switches 5 and 9, which will be described later. The securing limit switch 16 is a control changeover switch having a low voltage contact 16a and a high voltage contact 16b, and the changeover piece 10c is switched in conjunction with the changeover switches 5 and 9.

17 is a transformer for control power supply;
It has secondary windings 17a and 17b, and both ends of the primary winding 17a and the intermediate tap tc are the contact points 9 of the changeover switch 9.
b, the other end of the circuit breaker 2b, and the contact 9a.

18 is a current limiting resistor whose one end is connected to the anode of the first diode 3a, 19 is a first control relay whose one end is connected to one end of the primary winding 10a of the auxiliary transformer 10, and 20 is connected by the first relay 19. It is an operating normally open cutoff relay contact, and is provided between the circuit breaker 2a and the anode of the first diode 3a.

21 is a control device, which has first to tenth connection terminals 21a to 21j;
1a and 21b are connected to both ends of the secondary winding 17b of the transformer 17, respectively, and the third and fourth connection terminals 2
1c and 21d are the switching pieces 16 of the switching switch 16
c, is connected to the high voltage contact 16b, and the fifth and sixth connection terminals 21e and 21f are connected to the other end of the circuit breaker 2a, and the resistor 1
8, and the seventh, ninth, and eighth connection terminals 21g, 21i, and 21h are connected to the other end of the auxiliary transformer 10.
Both ends of the next winding 10a are connected to the intermediate tap ta, and the tenth connection terminal 21j is connected to the other end of the first relay 19.

Next, a second section showing detailed wiring of the control device 21 is shown.
The diagram will be explained.

In FIG. 2, 22 is a full-wave rectifier circuit with a diode bridge configuration in which a pair of AC input terminals are connected to the first and second connection terminals 21a and 21b, respectively, and 23 is a positive and negative output terminal of the rectifier circuit 22. The smoothing capacitor 24 provided in between is a first Zener diode whose one end is connected to the positive output terminal of the rectifier circuit 22, and whose anode is connected to the negative output terminal of the rectifier circuit 22 via the second resistor 25. It is turned on only when the AC power supply on the primary side of the transformer 17 is 200V with the changeover switch 9 being switched to the low voltage contact 9a.

27 is an NPN type transistor whose base is connected to the anode of the Zener diode 24 via the input resistor 26, and whose emitter is connected to the rectifier circuit 22.
is connected to the negative output terminal of 28 is a voltage dividing resistor whose one end is connected to the positive output terminal of the rectifier circuit 22;
29 has both ends connected to the other end of the resistor 28 and the transistor 27
voltage dividing resistors, 30 connected to the collectors of each
is a time constant capacitor whose both ends are connected to the other end of the resistor 28 and the emitter of the transistor 27, 31 is a second Zener diode whose one end is connected to the other end of the resistor 28, and the changeover switch 9 is a high voltage contact. 9b, transformer 1
It turns off only when the AC power supply on the primary side of 7 is 100V.

32 is an NPN type transistor whose base and emitter are connected to the other end of the second Zener diode 31 and the negative output terminal of the rectifier circuit 22, and 33 has one end connected to the positive output terminal of the rectifier circuit 22 and the third connection terminal 21c. A second relay is connected, and the other end is connected to the collector of the transistor 32.

34 is a normally open contact of the second relay 33 provided between the fifth and sixth connection terminals 21e and 21f, 35 is a seventh diode for surge absorption connected in anti-parallel to the second relay 33, and 36 is a seventh diode for surge absorption. 4 connection terminal 21d,
The third relays 37 and 38 provided between the collectors of the fourth transistor 32 have one end connected to the seventh relay,
The normally open contacts and normally closed contacts 39 of the third relay 36, which are connected to the eighth connection terminals 21g and 21h and whose other ends are both connected to the sixth connection terminal 21f, are connected in antiparallel to the third relay 36. This is the eighth diode for surge absorption.

40 and 41 are the positive output terminal of the rectifier circuit 22 and the fourth
Two voltage dividing resistors 42 are connected in series with the collector of the transistor 32, and the emitter is connected to the positive output terminal of the rectifier circuit 22, and the base is connected to the resistors 40 and 41. Connected to the dots.

43 has one end connected to the collector of the transistor 42 and the other end connected to the rectifier circuit 2 via the capacitor 44.
A current limiting resistor 45 is connected to the negative output terminal of No. 2, and a fourth current limiting resistor 45 is connected to the positive output terminal of the rectifier circuit 22 at one end.
Relay, 46 is the 9th and 10th connection terminal 21i, 21
a normally open contact point of a fourth relay 45 provided between j;
47 is a ninth diode for surge absorption connected in antiparallel to the fourth relay 45.

48 is an NPN transistor whose collector and emitter are connected to the other end of the fourth relay 45 and the negative output terminal of the rectifier circuit 22, and 49 is a resistor 43.
The other end is a third Zener diode provided between the base of the sixth transistor 48, and when the changeover switch 9 is switched to the low voltage contact 9a and the AC power supply on the primary side of the transformer 17 is 100V. Turn on only when

In the first case, the AC power supply is a low voltage of 100V, and each changeover switch 5, 9,
16 to the low voltage contacts 5a, 9a, 16a and set the correct low voltage, limit switch 1
5. An AC voltage of 100V is applied to the primary winding 17a of the transformer 17 via the switching piece 9c of the changeover switch 9 and the contact 9a, and the voltage across the secondary winding 17b is rectified by the rectifier circuit 22 and the capacitor 23. smoothed.

At this time, the first Zener diode 24 is turned off, so the transistor 27 is turned off, and the capacitor 30 is charged via the resistor 28.
0 charging, the potential at one end of the second Zener diode 31 becomes higher than the Zener voltage, this diode 31 is turned on, the transistor 32 is turned on, the second relay 33 is energized, and the normally open contact 34 is closed. Thus, both ends of the contact 20 are bridged.

Note that by switching the changeover switch 16 to the first contact 16a, the third relay 36 is maintained in a non-excited state.

Furthermore, when the transistor 32 is turned on, the transistor 42 is turned on and the capacitor 44 is charged via the resistor 43. When the potential at one end of the third Zener diode 49 becomes equal to or higher than the Zener voltage as the capacitor 44 is charged, the third Zener diode 49 is turned on, transistor 48 is turned on, fourth relay 45 is energized, and contact 46 is closed.

By this closing, the first relay 19 is energized and the contact 20 is closed, and 100V AC power is supplied to the rectifier circuit 3.

Then, the 100V AC power source is voltage doubled and rectified by a voltage doubler rectifier circuit including first and second diodes 3a, 3b, capacitors 4a, 4b, and changeover switch 5.
A DC voltage of approximately 200V, which is twice as high, is generated across the series circuit 4.

At this time, 100V AC power is also applied to the primary side of the auxiliary transformer 10 via the closed contacts 34 and 38, and the drive circuit 11 is activated, causing the switching elements 6a and 6b of the inverter 8 to perform high-frequency switching operation. do.

Then, the DC voltage is converted into a high frequency output by the inverter 8, and the high frequency output via the output transformer 7 is transmitted to the fifth and sixth diodes 12a and 12b.
The output is rectified and smoothed by the output rectifier circuit 12 and reactor 13, and a predetermined DC welding voltage is applied to the welding load between the output terminals 14a and 14b.

Next, as a second case, the AC power supply is high voltage 200V, and each changeover switch 5, 9, 1
6 to the high voltage contacts 5b, 9b, and 16b to set the correct high voltage, an AC voltage of 200V is applied to the primary winding 17a of the transformer 17, and at this time,
By switching the changeover switch 9 to the contact 9b, the turns ratio (primary/secondary) of the primary and secondary windings 17a, 17b of the transformer 17 becomes 1/2 of that in the first case, so that the rectifier circuit 22 The same voltage as in the first case is applied to.

Therefore, by the same operation as in the first case, the transistors 32, 42, 48 are turned on, the second and fourth relays 33, 45 are energized, and the contact 3 is turned on.
4,46 is closed.

Then, by closing the contact 46, the first relay 19
is excited, the contact 20 is closed, and 200V AC power is supplied to the rectifier circuit 3.

At this time, the first to fourth diodes 3a to 3d,
Due to the full wave rectifier circuit of both capacitors 4a and 4b
A 200V AC power source is full-wave rectified and smoothed, and a DC voltage of approximately 200V is generated across the series circuit 4.

Also, by switching the changeover switch 16 to the contact 16b, unlike the first case, the third relay 3
6 is excited, the contact 37 is closed, and the contact 38 is opened, and an AC voltage of 200 V is applied to the primary winding 10a of the auxiliary transformer 10 via the contact 37.

At this time, the turns ratio of the primary and secondary windings 10a and 10b of the auxiliary transformer 10 becomes 1/2 of that in the first case, and the same voltage as in the first case is applied to the drive circuit 11.

Then, a switching signal similar to that in the first case is outputted from the drive circuit 11 to the switching elements 6a, 6b of the inverter 8, and the switching elements 6a, 6b perform high frequency switching.

This high frequency switching converts the DC voltage into a high frequency output, and the fifth and sixth diodes 1
2a, 12b, and the rectification and smoothing of the reactor 13, a predetermined welding voltage approximately the same as in the first case is applied to the welding load.

Next, as a third case, even though the AC power supply is a high voltage of 200V, each changeover switch 5,
9, 16 to the low voltage contacts 5a, 9a, 16a, an AC voltage of 200V is applied to the primary winding 17a of the transformer 17, and at this time, the primary and secondary windings 17a, Since the turns ratio of 17b is 1/1, which is twice that of the second case, the rectifier circuit 2
The applied voltage in case 2 is twice that in the first and second cases.

Therefore, the first Zener diode 24 is turned on and the transistor 27 is turned on, and the potential at one end of the second Zener diode 31 does not become higher than the Zener voltage, and the second Zener diode 31 is kept off and the transistor 32 is turned off. However, both the second and third relays 33 and 36 become non-energized.

Furthermore, the transistor 42 is turned off and the third Zener diode 49 is also held off, and the transistor 48 is turned off and the fourth relay 45 is also placed in a non-energized state.

Then, the energizing path of the first relay 19 is kept open by turning off the contact 46 of the fourth relay 45, the first relay 19 is de-energized, the contact 20 is kept open, and the rectifier circuit 3 is supplied with alternating current. Power is not supplied.

Therefore, the first and second diodes 3a, 3
b, capacitors 4a, 4b, switching element 6
A high voltage twice the normal voltage (400 V) based on voltage doubler rectification is not applied to a and 6b, and damage to these circuit components due to application of abnormal high voltage is prevented.

Further, since the contacts 34 of the second relay 33 are held open and voltage application to the primary winding 10a of the auxiliary transformer 10 is also cut off, damage to the drive circuit 11 due to application of abnormally high voltage is also prevented.

Next, as a fourth case, even though the AC power supply is a low voltage of 100V, each changeover switch 5,
9, 16 to the high voltage contacts 5b, 9b, 16b, if a setting error occurs, an AC voltage of 100V is applied to the primary winding 17a of the transformer 17, and at this time, the primary and secondary windings 17a, Since the turns ratio of 17b is 1/2, which is 1/2 of that in the first case, the rectifier circuit 2
The applied voltage in case 2 is 1/2 of that in case 1 and 2,
The voltage applied to the rectifier circuit 22 is also 1/2 that of the second case described above.

Therefore, the first Zener diode 24 is turned off and the third transistor 27 is turned off, and the potential at one end of the second Zener diode 31 does not exceed the Zener voltage as in the third case, and the second Zener diode 31 The fourth transistor 3 is held off.
2 is turned off, and the second and third relays 33 and 36 are both de-energized.

Furthermore, the transistor 42 is turned off and the third Zener diode 49 is also held off, and the transistor 48 is turned off and the fourth relay 45 is also placed in a non-energized state.

Therefore, the situation is the same as in the third case,
In this case as well, AC power is not supplied to the rectifier circuit 3, and the first to fourth diodes 3a to 3d, capacitors 4a and 4b, and switching elements 6a and 6
b and the voltage applied to the drive circuit 11 is cut off.

Note that the configuration of the control device 21 is not limited to the embodiment.

Further, each relay 19, 33, 36, 45 may be a non-contact relay.

For example, high voltage and low voltage of AC power supply are
This idea can be applied even to 400V and 200V.

In addition, a warning device such as a display lamp or a buzzer may be attached to notify an abnormality when the third or fourth case occurs.

[Effect of idea]

As described above, according to the DC power supply device of this invention, the voltage setting of the device based on the switching of the rectification method selector switch 5 is correctly set to high voltage or low voltage with respect to high voltage or low voltage of AC power supply. Since the control device 21 closes the normally open cutoff relay contact 20 and supplies AC power to the bridge rectifier circuit 3 only when the device is in the Therefore, the AC power supply is not supplied to the rectifier circuit 3, and in particular, when the AC power supply is at a high voltage and the device is set to a low voltage, the rectifier circuit 3's first and second rectifying diodes 3a, 3b, capacitors 4a, 4b, etc. When a voltage doubler rectifier circuit is formed by the changeover switch 5, each of the diodes 3a to 3d, capacitors 4a, 4b, and switching element 6a of the rectifier circuit 3 due to abnormally high voltage
6b can be prevented from being damaged, and the reliability of the device can be improved.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 show one embodiment of the DC power supply device of the present invention, Fig. 1 is a wiring diagram, Fig. 2 is a detailed wiring diagram of a part of Fig. 1, and Fig. 3 is a conventional example. FIG. 3... Bridge rectifier circuit, 3a to 3d... First to fourth diodes for rectification, 4a, 4b... Smoothing capacitor, 4... Series circuit, 5... Rectification method selection switch, 6a, 6b... For inverter First and second switching elements, 7... Output transformer, 7a, 7b... Primary and secondary windings, 12... Output rectifier circuit, 20... Breaking relay contact, 21...
…Control device.

Claims (1)

[Claims for Utility Model Registration] A pair of terminals 1a and 1b that are selectively connected to two types of AC power sources, high voltage and low voltage, and a bridge rectifier circuit 3 whose anode is connected to the terminal 1a. a first rectifying diode 3a; a second rectifying diode 3b of the rectifier circuit 3 whose cathode is connected to the anode of the first diode 3a; and a cathode and an anode connected to the first diode 3a.
a third rectifying diode 3c of the rectifying circuit 3 connected to the cathode and the terminal 1b, respectively; a cathode and an anode of the third diode 3;
c, a fourth rectifying diode 3d of the rectifying circuit 3 connected to the anodes of the second diode 3b, and a cathode of the first diode 3a and the second diode 3b;
2 provided between the anode of diode 3b
A rectification method selector switch that closes or opens a connection between a series circuit 4 of two smoothing capacitors 4a and 4b, a connection point between the two capacitors 4a and 4b, and an anode of the third diode 3c depending on a high voltage setting or a low voltage setting. 5, two inverter switching elements 6a, 6b which are connected in series between both ends of the series circuit 4 and perform high frequency switching in opposite phases, and both ends of the primary winding 7a are connected to both the switching elements 6a, 6b. point, both the capacitors 4a, 4
Output transformer 7 connected to each connection point of b
an output rectifier circuit 12 connected to the secondary winding 7b of the transformer 7; a normally open cutoff relay contact 20 provided between the terminal 1a and the anode of the first diode 3a; When the AC power source is high voltage and the changeover switch 5
A control device 21 that closes the relay contact 20 only when the AC power source is set to a high voltage, the AC power source is a low voltage, and the changeover switch 5 is set to a low voltage.