JP2000166221A - Double chopper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect failure in the short-circuit of a switching element positively by detecting the voltage difference or the voltage ratio of the first and second input-side capacitors, and regarding the first or second switching element as abnormal for protective detection when a detected value is equal to a prescribed set area or higher. SOLUTION: Both switching elements 8a, 8b are energized at 180 deg. alternately under normal conditions, and output the voltage, or voltage E/2 of filter capacitors 7a, 7b as the first and second input-side capacitors having the same specification as each other. Both voltages of the filter capacitors 7a, 7b are E/2, so that the absolute value of the difference of detected values from voltage detectors 13a, 13b become 0. When the detected voltage difference from the voltage detectors 13a, 13b is equal to a prescribed set area or higher, a control circuit 14 regards a switching element 8a or 8b as abnormal for protective detection. It is thus possible to detect failure in the short-circuit of both switching elements 8a, 8b positively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double chopper device, and more particularly to a technology for reliably detecting and detecting an abnormality in a switching element.

[0002]

2. Description of the Related Art FIG. 7 shows a GTO double chopper transistor inverter device for vehicle auxiliary power supply (No. 2), for example, in the Proceedings of the Institute of Electrical Engineers of Japan 1987, 889.
FIG. 3 is a circuit diagram showing a conventional vehicle auxiliary power supply device using a double chopper. In the figure, reference numeral 51 denotes a pantograph which receives power from a high voltage overhead line 65 which is a DC feeder,
2 converts a DC voltage having a large fluctuation into a stable voltage 2
The circuit configuration and features of the heavy chopper will be further described later.

[0005] Reference numeral 53 denotes a filter unit for smoothing the output voltage of the chopper, which comprises a reactor 53a and a capacitor 53b. Reference numeral 54 denotes a three-phase inverter (inverter circuit) that converts DC power into AC power. Reference numeral 55 denotes a leakage transformer which converts an inverter output into a voltage required by a load and electrically insulates a high voltage side and a low voltage side circuit.
6 is a three-phase filter capacitor, 57 is a load connected to the auxiliary power supply, 58 is an output voltage detector for detecting an output voltage, 59 is an output voltage reference of a controller described later, 60
Is a chopper output voltage detector for detecting a chopper output;
1 is a chopper output voltage reference of the controller, 62 is a pulse generating circuit that outputs a pulse having a predetermined duty ratio that the chopper should operate according to a control voltage command, 63 is a regulation drop of an output voltage generated by a load current of the transformer 55 or the like. Is a chopper output voltage controller for controlling the chopper so that the chopper output voltage becomes a stable constant voltage with respect to the input voltage fluctuation.

Next, the operation will be described. The high voltage input from the high voltage overhead line 65 having a large voltage fluctuation by the pantograph 51 is converted into a stable low voltage by the double chopper 52. The ripple of the double chopper output voltage is removed by a filter composed of the reactor 53a and the capacitor 53b of the chopper output filter unit 53, and is input to the inverter circuit 54 as a DC voltage with little ripple. The inverter circuit 54 converts the DC voltage output from the chopper into a three-phase AC voltage, and performs a 12 / pulse operation. The vehicle auxiliary power supply as a whole has no voltage control function other than the double chopper 52. This three-phase AC voltage is insulated and boosted through a transformer 55, and a harmonic is removed by a three-phase filter capacitor 56, and is output to a load 57. The circuit of the transformer 55 and the three-phase filter capacitor 56 at the subsequent stage of the inverter circuit 54 has a transformer 55 for the purpose of improving the voltage waveform.
And the equivalent LC filter configuration of the three-phase filter capacitor 56 sufficiently attenuates the harmonics contained in the output voltage of the inverter circuit 54 to supply the load 57 with a sine wave output voltage. Since this output voltage is voltage-controlled by the double chopper 52, the output voltage is detected by the output voltage detector 58, input to the output voltage controller 63 together with the output of the output voltage reference 59, and the difference between the two is output. . The output of the output voltage controller 63 is input to the chopper output voltage controller 64 together with the output of the chopper output voltage reference 61 and the output of the chopper output voltage detector 60, and the conduction ratio at which the double chopper 52 should operate is determined. The pulse generation circuit (chopper controller) 62 outputs a gate pulse to the double chopper 52 based on the output from the chopper output voltage controller 64, and the double chopper 52 controls the output voltage according to the gate pulse.

Next, the features of the double chopper and its protection detection operation, which is the subject of the present application, will be described with reference to FIG. 8 showing the internal configuration of the double chopper 52. In FIG. 8, 70a and 70b are connected in series with each other, and capacitors connected to a DC voltage input terminal, and 71a and 71b are GT
Switching elements such as O, and 72a and 72b are flywheel diodes. 73a and 73b are voltage detectors for detecting the voltages of the capacitors 70a and 70b, respectively.
Reference numerals “a” and “74b” denote comparators that perform protection detection by comparing the detection values from the voltage detectors 73a and 73b with the voltage protection set value 75, respectively.

The double chopper is called a single chopper in comparison with the single chopper. The single chopper has one switching element in a circuit, and performs DC voltage control only by turning on and off the one switching element. In this case, assuming that the chopper input voltage is E (V), the chopper output voltage is 0 (zero).
And + E, the output voltage and current have waveforms with large ripples, and it is necessary to increase the size of a filter circuit for smoothing the waveform.

On the other hand, the double chopper has two switching elements in a circuit as shown in FIG. 8 and is provided on the positive side and the negative side, respectively. ° Adopt a method of turning on and off by shifting the phase. Then, each of the two capacitors having the same capacitance has a half of the chopper input voltage E (V),
By sharing 0.5E (V), three-level voltage output is enabled. That is, when both of the switching elements are off, the chopper output voltage is 0 (V), when one is on and the other is off, 0.5 E (V), and when both are on, E (V). . As a result, the output voltage and current ripples can be reduced, and the filter circuit can be simplified.

When the switching element 71a or 71b becomes short-circuited or the like, any one of the capacitors 70a and 70b
Since the voltage of b rises more than usual, this is detected by the voltage detectors 73a and 73b. When the voltage becomes equal to or higher than the predetermined voltage protection set value 75, the comparator 74a or 74b outputs a signal to perform protection detection.

[0009]

Incidentally, a train that travels over a long distance sometimes runs through an AC electrified section and a DC electrified section. In these electric vehicles,
A DC power supply directly supplied from a DC overhead wire and a DC power supply supplied from an AC overhead wire via a transformer and a rectifier are switched and used according to a traveling section. In such a case, since the protection detection of the conventional double chopper device in particular is configured as described above, there is a problem that it is difficult to realize reliable protection detection. That is, in order to avoid malfunction of protection detection, the voltage protection set value 75 must be determined in consideration of the fluctuation range of the DC input voltage. However, when the DC power supplied in the AC / DC section described above is switched, Generally, the voltage protection set value is determined in consideration of the power supply voltage fluctuation in an AC section having a large voltage fluctuation range. As a result, for example, when power is supplied in a DC section, the protection detection level is too high, and there is a possibility that a short circuit abnormality of the switching element cannot be reliably detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a reliable protection detection operation can be obtained even when switching between two DC power supplies having different voltage fluctuation ranges. It is an object of the present invention to provide a double chopper device.

[0011]

According to the present invention, there is provided a power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage fluctuation range different from that of the first DC power supply. A series connection of first and second input-side capacitors connected between output terminals of a power supply circuit, and an intermediate connection point between the first and second input-side capacitors connected to an intermediate connection point between the first and second input-side capacitors. A second flywheel diode connected in series, a first switching element connected between a positive electrode side of the first input-side capacitor and a cathode of the first flywheel diode, the second input side A second switching element connected between the negative electrode side of the capacitor and the anode of the second flywheel diode, and a series connection of the first and second flywheel diodes A double-side chopper device for controlling the voltage of the output-side capacitor to a desired value by turning on and off the first and second switching elements. The double chopper device according to the first aspect detects a voltage difference or a voltage ratio between the first and second input-side capacitors, and when the detected value exceeds a predetermined set range, the first or second switching element. It is provided with a means for performing protection detection by regarding the abnormality as an abnormal state.

A double chopper device according to a second aspect of the present invention detects the voltage of the output-side capacitor, and when the detected value is equal to or greater than a predetermined set value, the abnormality of the first or second switching element is determined. It is provided with means for deeming protection and detection.

According to a third aspect of the present invention, there is provided a double chopper device for detecting a voltage of the first and second input-side capacitors, and wherein the power supply circuit selects one of a first and a second DC power supply. Means for judging whether or not the voltage detection value is equal to or greater than a predetermined set value, means for detecting that the first or second switching element is abnormal, and detecting the protection. A means for changing the set value of the means is provided.

A double chopper device according to a fourth aspect of the present invention detects the currents of the first and second switching elements, and detects the currents in spite of the fact that an OFF command is issued to the switching elements. In this case, the switching device is provided with a means for performing protection detection by assuming that the switching device is abnormal.

According to a fifth aspect of the present invention, in the double chopper device, the first DC power supply is a power supply supplied from a railway DC feeder, and the second DC power supply is an AC supply from a railway AC feeder. The power supply is a DC power supply with a rectifier and has a voltage fluctuation range larger than that of the first DC power supply.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a circuit diagram of a double chopper device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an AC power supplied from a railway AC feeder via a pantograph or a transformer (not shown);
Reference numeral 2 denotes a rectifier for converting an AC voltage to a DC voltage. Reference numeral 3 denotes a DC power supply supplied from a railway DC feeder through a pantograph (not shown). Reference numerals 4a, 4b, 4c, and 4d denote switches provided on the input side. 4a, 4b, 4c, and 4d are opened and closed in conjunction with each other to switch between the AC power supply 1 and the DC power supply 3. 5 is a DC high-speed circuit breaker, 6 is a filter reactor, 7a and 7b are filter capacitors as first and second input-side capacitors having the same specifications, and a filter reactor 6 and a filter capacitor 7 are provided.
The input filter circuit is formed by a and 7b. 8
Reference numerals a and 8b denote first and second switching elements for the chopper for controlling the inverter circuit input to a predetermined voltage value, and reference numerals 9a and 9b denote first and second flywheel diodes 10 and 10 for the chopper circuit. Is a filter reactor, and 11a and 11b are filter capacitors which are output side capacitors. The filter reactor 10 and the filter capacitors 11a and 11b smooth the chopper output. Reference numeral 12 denotes an inverter circuit for converting a DC voltage to an AC voltage, and reference numerals 13a and 13b denote filter capacitors 7a and 7b.
Is a control circuit for determining protection detection based on the outputs of the voltage detectors 13a and 13b.

Next, the operation will be described. When the input is the DC power supply 3, the changeover switches 4a and 4c are open and the changeover switches 4b and 4d are closed.
And DC power supply 3 → changeover switch 4 b → high speed circuit breaker 5 → filter reactor 6 → filter capacitor 7 a
The filter capacitors 7a and 7b are charged along the path of the filter capacitor 7b, the changeover switch 4d, and the DC power supply 3, and the voltage between the terminals of the filter capacitors 7a and 7b becomes half the DC power supply voltage. When the input is the AC power supply 1, the changeover switches 4a and 4c are closed and the changeover switches 4b and 4d are open.
After the AC power supply 1 is converted into a DC voltage by the rectifier 2, the rectifier 2 → the changeover switch 4a → the high speed circuit breaker 5 → the filter reactor 6 → the filter capacitor 7a →
The filter capacitors 7a and 7b are charged through the path of the filter capacitor 7b, the changeover switch 4c, and the rectifier 2, and the voltage between the terminals of the filter capacitors 7a and 7b becomes 1/2 of the output of the rectifier 2.

When both the switching elements 8a and 8b are turned on, the filter capacitor 7a, the switching element 8a, the filter reactor 10, the filter capacitor 11a, the filter capacitor 11b, the switching element 8b, and the filter capacitor 7b pass through the filter capacitor 7a. 7b to the filter capacitor 11a,
11b is charged. Next, when the switching element 8a is on and the switching element 8b is off, the filter capacitor 7a → the switching element 8a → the filter reactor 10 → the filter capacitor 11a → the filter capacitor 11b → the flywheel diode 9b → the filter capacitor along the filter capacitor 7a. From 7a, the filter capacitors 11a and 11b are charged. Conversely, when the switching element 8a is off and the switching element 8b is on, the filter capacitor 7b → the flywheel diode 9a → the filter reactor 10 → the filter capacitor 1
1a → filter capacitor 11b → switching element 8
b → charging the filter capacitors 11a and 11b from the filter capacitor 7b through the path of the filter capacitor 7b. Further, when both switching elements 8a and 8b are off, filter capacitors 11a and 11b are not charged from filter capacitors 7a and 7b. Therefore, the on / off control of the switching elements 8a and 8b in this manner allows the filter capacitors 11a and 11b to be controlled.
The voltage between the terminals b can be controlled. Actually, the switching elements 8a and 8b are turned on and off so as to output a predetermined constant voltage by absorbing a change in the input voltage.

Next, the protection detecting operation at the time of short circuit will be described with reference to the timing chart of FIG. Here, in the normal state (corresponding to the left half of FIG. 2), both switching elements 8
a and 8b are alternately energized by 180 °. In this operation mode, as described above, the voltages of the filter capacitors 7a and 7b, that is, the voltage E / 2
(E is a chopper input voltage), and the chopper output voltage V3 is as shown in FIG. Further, the voltages V1 and V2 of the filter capacitors 7a and 7b are both E /
2, the absolute value | V1-V2 | of the difference between the detection values from the voltage detectors 13a and 13b is zero. This state is not affected by the voltage fluctuation of the DC power supply.

Assuming that a short-circuit fault occurs in the switching element 8a at the time T1 when the switching element 8b is on, equivalently, a parallel connection of the filter capacitor 7a and the filter capacitors 11a and 11b, and the filter capacitor 7b Are connected in series between the positive and negative terminals of the DC power supply. Therefore, the voltage of E / 2 has been applied to the filter capacitor 7a by connecting the filter capacitors 7a and 7b in series until then. However, after the short circuit occurs, the impedance ratio including the filter capacitors 11a and 11b is changed. The voltage of the filter capacitor 7a decreases and becomes (E / 2−ΔE) at time T2. On the contrary, the filter capacitor 7b rises to (E / 2 + ΔE).
As a result, if the short circuit continues, the output voltage V3 becomes
(E). Actually, the voltage is smoothed by the filter effect, and if the constant voltage control is functioning, the conduction width of the switching element 8b should be reduced at a predetermined response speed so that the smoothed voltage becomes E / 2. It is.

In any case, the filter capacitor 7a,
As shown in FIG. 2 (f), the voltage difference | V1-V2 | of 7b rises from zero immediately after the occurrence of the short circuit, and assumes a value of 2ΔE. As described above, when the switching element is normal, the voltage difference | V1−V2 | is zero and is not affected by the voltage fluctuation of the DC power supply. Therefore, the set value used as the abnormality determination reference is the filter capacitor 7a, 7b. Only a voltage difference due to a slight capacitance difference due to a manufacturing error needs to be considered, and an extremely low value, that is, a difference from a normal value can be reduced.
Therefore, regardless of the type of DC power supply, a reliable protection detection operation can always be obtained.

In the above description, the filter capacitor 7
The abnormality determination is performed based on the detected voltage difference between a and 7b. However, the detected voltage ratio between the two is determined, and when the voltage ratio exceeds a predetermined range around 1.0, it is determined that an abnormality has occurred. The same effect can be obtained by performing the above operation.

Embodiment 2 FIG. In the first embodiment, the protection is detected by looking at the voltage difference or the voltage ratio between the terminals of the filter capacitors 7a and 7b. However, as shown in FIG. 3, the voltage detection for detecting the voltage between the terminals of the filter capacitors 11a and 11b is performed. To the filter capacitor 1
A similar effect can be obtained by performing protection detection when the sum of the terminal voltages of 1a and 11b is higher than a predetermined set value.
That is, the voltage between the terminals of the filter capacitors 11a and 11b is controlled by the on / off control of the switching elements 8a and 8b according to the voltage between the terminals of the filter capacitors 7a and 7b, but only one of the switching elements 8a and 8b is controlled. Is short-circuited, it deviates from the normal control operation output, and the voltage between the terminals of the filter capacitors 11a and 11b increases.
7b, the filter capacitor 11
When the voltage between the terminals a and 11b is higher than a predetermined set value, the protection is detected by regarding the switching elements 8a and 8b as abnormal. In this case, since the output of the chopper circuit is detected, the abnormal state of the chopper circuit is surely recognized, and the reliability of the abnormality detection is improved.

Embodiment 3 FIG. In the first embodiment, the protection is detected by checking the voltage difference or voltage ratio between the terminals of the filter capacitors 7a and 7b. However, as shown in FIG. 4, the protection switches are switched from the open / closed state of the switches 4a and 4b (4c and 4d). , By detecting whether the input is a DC power supply or an AC power supply, and in each case, by changing the set value 16 of the voltage protection between the terminals of the filter capacitors 7a and 7b to an appropriate set value, Even when only the switching element is short-circuited, the protection can be detected. That is, conventionally, when the input is an AC power supply, the input voltage fluctuation range is large. Therefore, the set value 16 of the filter capacitor voltage protection is set to an appropriate setting value corresponding to the AC power supply having a large voltage fluctuation range. Even when the input is a DC power supply, the set value of the filter capacitor voltage protection is the same. However, if the changeover switch 4a (4c) is open and the changeover switch 4b (4d) is closed, it can be determined that the input is a DC power supply. In this case, the set value 16 of the filter capacitor voltage protection is determined. Is changed to an appropriate lower set value in consideration of a DC power supply having a small voltage fluctuation range, the operating conditions of the comparators 17a and 17b for detecting voltage protection can be changed. Therefore, the voltage between the terminals of the filter capacitor 7a or 7b becomes high when only one of the switching elements is short-circuited, but it is ensured by changing the voltage protection set value 16 to an optimum value according to the type of power supply. Can detect protection.

Embodiment 4 In the third embodiment, the detection of the input power source type is performed in the open / closed state of the changeover switch. However, as shown in FIG.
a and 18b are attached, and whether the input is an AC power supply or a DC power supply can be determined based on the detected current, and the same effect as in the third embodiment can be obtained.

Embodiment 5 In the first embodiment, the protection detection is performed by checking the voltage difference between the terminals of the filter capacitors 7a and 7b. However, as shown in FIG. 6, the current detector 1 can detect the current flowing through the switching elements 8a and 8b.
If the output of the current detectors 19a, 19b corresponding to the command to turn off the switching element 8a or 8b is output even if a command to turn off the switching element 8a or 8b is issued, the switching is performed. It can be determined that the element is in an abnormal state such as a short circuit failure. In this case, since the abnormal state is directly detected from the current flowing through the switching elements 8a and 8b, the reliability of the abnormality detection is significantly improved.

In each of the above embodiments, the case where the AC power supply and the DC power supply are switched as the power supply circuit has been described. However, even if the same AC power supply has different voltage fluctuation ranges due to different frequencies, for example. The present invention can be similarly applied to a case where the first and second DC power supplies obtained by converting each of these AC power supplies into DC are switched to form a power supply circuit, and the same effects are obtained.

[0028]

As described above, the present invention provides a power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage variation range different from that of the first DC power supply, A series connection of first and second input-side capacitors connected between output terminals of the power supply circuit, and an intermediate connection point of the first and second input-side capacitors connected to an intermediate connection point of the first and second input-side capacitors. And a series connection of a second flywheel diode, a first switching element connected between the positive electrode side of the first input-side capacitor and a cathode of the first flywheel diode, the second input A second switching element connected between the negative electrode of the side capacitor and the anode of the second flywheel diode, and a serial connection of the first and second flywheel diodes 2. A double chopper device comprising an output-side capacitor connected in parallel with the first and second switching elements and controlling the voltage of the output-side capacitor to a desired value by turning on and off the first and second switching elements. The present invention detects a voltage difference or a voltage ratio between the first and second input-side capacitors, and protects the first and second switching elements when the detected value exceeds a predetermined set range, assuming that the first or second switching element is abnormal. Since the detection means is provided, the protection of the switching element can be reliably detected without being affected by the voltage fluctuation of the power supply circuit.

Further, according to a second aspect of the present invention, the voltage of the output side capacitor is detected, and when the detected value is equal to or more than a predetermined set value, the protection of the first or second switching element is regarded as abnormal. Therefore, the protection of the switching element can be reliably detected from the output characteristic based on the disturbance of the voltage control characteristic.

The invention according to claim 3 is means for detecting the voltage of the first and second input-side capacitors, and determining which of the first and second DC power supplies is selected by the power supply circuit. Means for detecting the abnormality of the first or second switching element when the voltage detection value is equal to or more than a predetermined set value, and detecting the protection, and setting value of the protection detection means according to the type of the DC power source determined. Is provided, it is possible to reliably detect the protection of the switching element without being affected by the difference in the voltage fluctuation range of the connected DC power supply.

Further, according to the present invention, the currents of the first and second switching elements are detected, and when the current is detected in spite of the fact that an OFF command is issued to the switching elements, Since the protection device is provided for detecting the abnormality of the switching element, it is possible to directly detect the abnormal state of the switching element from the operation response of the switching element.

According to a fifth aspect of the present invention, the first DC power source is a power source supplied from a railway DC feeder, and the second DC power source is a rectifier that converts AC from the railway AC feeder. Since the power supply has a voltage fluctuation range larger than that of the first DC power supply, in the double chopper device employed in the electric vehicle operating in both the AC and DC sections, it is possible to reliably detect the protection of the switching element. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a double chopper device according to Embodiment 1 of the present invention.

FIG. 2 is a timing chart for explaining a short-circuit failure operation of a switching element in the double chopper device of FIG.

FIG. 3 is a circuit diagram showing a double chopper device according to Embodiment 2 of the present invention.

FIG. 4 is a circuit diagram showing a double chopper device according to Embodiment 3 of the present invention.

FIG. 5 is a circuit diagram showing a double chopper device according to Embodiment 4 of the present invention.

FIG. 6 is a circuit diagram showing a double chopper device according to a fifth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a conventional auxiliary power supply device for a vehicle using a double chopper.

FIG. 8 is a circuit diagram showing a configuration of a double chopper.

[Explanation of symbols]

1 AC power supply, 2 rectifier, 3 DC power supply, 4 changeover switch, 7a, 7b filter capacitor, 8a,
8b switching element, 9a, 9b flywheel diode, 11a, 11b filter capacitor, 12
Inverter circuit, 13a, 13b voltage detector, 14
Control circuit, 15 voltage detector, 16 voltage protection set value, 17a, 17b comparator, 19a, 19b current detector.

Claims (5)

[Claims] 1. A power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage fluctuation range different from that of the first DC power supply, and connected between output terminals of the power supply circuit. Series connection of the first and second input-side capacitors, and a series connection of the first and second flywheel diodes whose intermediate connection point is connected to the intermediate connection point of the first and second input-side capacitors. Connection body, the first
A first switching element connected between the positive side of the input side capacitor and the cathode of the first flywheel diode, the negative side of the second input side capacitor and the anode of the second flywheel diode A second switching element connected between the first and second flywheel diodes, and an output-side capacitor connected in parallel with the series connection of the first and second flywheel diodes. In a double chopper device for controlling the voltage of the output side capacitor to a desired value by turning on / off, a voltage difference or a voltage ratio between the first and second input side capacitors is detected, and the detected value is set within a predetermined setting range. In the above case, there is provided a means for performing protection detection by assuming that the first or second switching element is abnormal.
Heavy chopper device. 2. A power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage fluctuation range different from that of the first DC power supply, and connected between output terminals of the power supply circuit. Series connection of the first and second input-side capacitors, and a series connection of the first and second flywheel diodes whose intermediate connection point is connected to the intermediate connection point of the first and second input-side capacitors. Connection body, the first
A first switching element connected between the positive side of the input side capacitor and the cathode of the first flywheel diode, the negative side of the second input side capacitor and the anode of the second flywheel diode A second switching element connected between the first and second flywheel diodes, and an output-side capacitor connected in parallel with the series connection of the first and second flywheel diodes. In the double chopper device which controls the voltage of the output side capacitor to a desired value by turning on and off, the voltage of the output side capacitor is detected, and when the detected value becomes equal to or more than a predetermined set value, the first or the second 2. A double chopper device comprising means for detecting protection by regarding the abnormality of the second switching element. 3. A power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage fluctuation range different from that of the first DC power supply, and connected between output terminals of the power supply circuit. Series connection of the first and second input-side capacitors, and a series connection of the first and second flywheel diodes whose intermediate connection point is connected to the intermediate connection point of the first and second input-side capacitors. Connection body, the first
A first switching element connected between the positive side of the input side capacitor and the cathode of the first flywheel diode, the negative side of the second input side capacitor and the anode of the second flywheel diode A second switching element connected between the first and second flywheel diodes, and an output-side capacitor connected in parallel with the series connection of the first and second flywheel diodes. In a double chopper device which controls the voltage of the output side capacitor to a desired value by turning on and off, the means for detecting the voltage of the first and second input side capacitors, and the power supply circuit is a first or second power supply circuit Means for determining which one of the DC power supplies is selected, and the first or second switch when the detected voltage value is equal to or greater than a predetermined set value. A double chopper device comprising: means for detecting protection assuming that the chucking element is abnormal; and means for changing a set value of the protection detection means according to the type of the DC power supply determined. 4. A power supply circuit for switching and outputting one of a first DC power supply and a second DC power supply having a voltage fluctuation range different from that of the first DC power supply, and connected between output terminals of the power supply circuit. Series connection of the first and second input-side capacitors, and a series connection of the first and second flywheel diodes whose intermediate connection point is connected to the intermediate connection point of the first and second input-side capacitors. Connection body, the first
A first switching element connected between the positive side of the input side capacitor and the cathode of the first flywheel diode, the negative side of the second input side capacitor and the anode of the second flywheel diode A second switching element connected between the first and second flywheel diodes, and an output-side capacitor connected in parallel with the series connection of the first and second flywheel diodes. In a double chopper device that controls the voltage of the output side capacitor to a desired value by turning on and off, the current of the first and second switching elements is detected, and an off command is issued to the switching elements. Nevertheless, when the current is detected, the switching element is regarded as abnormal, and a protection detection unit is provided. Double chopper device. 5. The first DC power supply is a power supply supplied from a railway DC feeder, and the second DC power supply is obtained by converting AC from a railway AC feeder into DC with a rectifier and has a voltage fluctuation range. 5. The power supply according to claim 1, wherein the power supply is larger than that of the first DC power supply.
Heavy chopper device.