JPWO2013001646A1 - Auxiliary power supply for vehicle - Google Patents

Abstract

A VVVF inverter device 4 that is mounted on a railway vehicle and includes a three-phase inverter circuit INV1 that converts DC power or AC power input from the overhead line 1 into desired AC power and supplies the load to the load, and drives the propulsion motor 7; A vehicle auxiliary power supply device 5 connected in parallel, wherein a blocking diode BD1 for preventing a backflow from the three-phase inverter circuit INV1 side to the overhead wire 1 side is provided between the overhead wire 1 and the three-phase inverter circuit INV1, An SiC Schottky barrier diode is applied to the blocking diode BD1.

Description

  The present invention relates to an auxiliary power supply for a vehicle that supplies desired power to, for example, an air conditioner, a lighting device, etc. of a railway vehicle.

  In the conventional auxiliary power supply for a vehicle, a blocking diode is inserted between the pantograph and a filter capacitor that smoothes the voltage applied from the overhead line via the pantograph, and a snubber circuit is provided in parallel with the blocking diode. The structure provided is common (for example, refer to the following nonpatent literature 1).

  Since many electric devices having a relatively large rated power are mounted on a railway vehicle, a large current flows through the blocking diode described above. In addition, during the operation of the railway vehicle, current always flows through the blocking diode. For this reason, it has been usual to provide a cooler (for example, a cooling fin) in the blocking diode so that the temperature of the blocking diode does not exceed an allowable value. In addition, due to the large capacity of the blocking diode, the snubber circuit connected in parallel to the blocking diode has inevitably increased in size.

"The 43rd Railroad Cybernet Symposium Proceedings", Japan Railway Cybernetics Council, published on November 30, 2006, paper number 512, page 3, Fig. 5

  As described above, in the conventional auxiliary power supply for a vehicle, the blocking diode cooling cooler and the blocking diode protection snubber circuit provided in association with the blocking diode inserted between the pantograph and the filter capacitor are: Despite the relatively small size of the blocking diode, it has been forced to increase its size. For this reason, there has been a great demand for downsizing of the cooler and the snubber circuit provided in association with the blocking diode while maintaining the function as the auxiliary power supply device for vehicles.

  The present invention has been made in view of the above, and an object of the present invention is to provide an auxiliary power supply device for a vehicle that can further reduce the size of a cooler and a snubber circuit provided in association with a blocking diode.

  In order to solve the above-described problems and achieve the object, an auxiliary power supply for a vehicle according to the present invention is mounted on a railway vehicle, converts DC power or AC power input from an overhead line into desired AC power, and loads it. An auxiliary power device for a vehicle that is connected in parallel with an inverter device that drives a propulsion motor, between the overhead wire and the inverter circuit, from the inverter circuit side. A blocking diode for preventing backflow to the overhead line side is provided, and this blocking diode is a Schottky barrier diode formed of a wideband semiconductor.

  According to the auxiliary power supply for a vehicle according to the present invention, there is an effect that the cooler and the snubber circuit provided in association with the blocking diode can be reduced in size.

FIG. 1 is a diagram schematically illustrating an example of a main circuit configuration in a railway vehicle according to an embodiment. FIG. 2 is a diagram illustrating an operation state in a normal state in the circuit configuration illustrated in FIG. FIG. 3 is a diagram showing an operation state when there is no blocking diode from the configuration of FIG. FIG. 4 is a diagram showing an operation state when there is a blocking diode contrary to FIG. FIG. 5 is a schematic circuit diagram for explaining the recovery operation of the blocking diode in the prior art. FIG. 6 is a time chart for explaining the recovery operation of the blocking diode in the prior art. FIG. 7 is a simplified circuit diagram for explaining the recovery operation when the Si diode is used as a blocking diode. FIG. 8 is a time chart showing a detailed operation state of the recovery operation when the Si diode is used as a blocking diode. FIG. 9 is a diagram for explaining an operation when a ground fault occurs in the DC bus on the other device side connected in parallel to the SIV. FIG. 10 is a time chart for explaining the operation when a ground fault as shown in FIG. 9 occurs. FIG. 11 is a circuit diagram for explaining the effect of the snubber circuit. FIG. 12 is a time chart for explaining the effect of the snubber circuit. FIG. 13 is a simplified circuit diagram for explaining a recovery operation when a SiC Schottky barrier diode is used as a blocking diode. FIG. 14 is a time chart showing a detailed operation state of the recovery operation when the SiC Schottky barrier diode is used as a blocking diode.

  Hereinafter, an auxiliary power supply for a vehicle according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

<Embodiment>
FIG. 1 is a diagram schematically illustrating an example of a main circuit configuration in a railway vehicle according to an embodiment of the present application. As shown in FIG. 1, the main circuit in the railway vehicle has a configuration having two main circuits. One of the main circuits is DC power (for example, DC750 (V), DC1500 (V), etc.) supplied from the overhead line 1 via the pantograph 2 installed on the roof of a railway vehicle (hereinafter simply referred to as “vehicle”). Is a circuit that forms a VVVF (Variable Voltage Variable Frequency) inverter device (hereinafter simply referred to as “VVVF”) 4 that controls the propulsion motor 7, and the other main circuit is connected in parallel with the VVVF 4, Similarly to this VVVF4, the DC power from the overhead line 1 is taken in, and in-vehicle electrical equipment other than the propulsion motor 7 (hereinafter referred to as “load”) such as lighting in the vehicle, air conditioner device, compressor, brake device, train information processing device, etc. 10 is a circuit that forms a vehicle auxiliary power supply (Static InVeter: SIV) 5 that supplies desired power to 10.

  SIV5 is connected to both ends (DC side terminals) of a three-phase inverter circuit INV1 and a three-phase inverter circuit INV1 in which a plurality (three in the example of FIG. 1) of a pair of upper and lower arms (switching elements) connected in series are connected in parallel. A filter capacitor FC1 connected in parallel and a transformer Tr connected to the AC terminal of the three-phase inverter circuit INV1 are configured, and the output of the transformer Tr is supplied to the load 10.

  SIV5 is a switch SW1 for electrically disconnecting the overhead line 1 and the main circuit, and is connected in series to the switch SW1, and is connected to the filter capacitor FC1 and the filter reactor FL1, SIV5 side for smoothing the input voltage to the three-phase inverter circuit INV1. A blocking diode BD1 for preventing a current from flowing backward to the VVVF4 side, and a snubber circuit 9 serving as a protection circuit for the blocking diode BD1. The snubber circuit 9 has a snubber capacitor Cs, a snubber resistor Rs connected in series to the snubber capacitor Cs, and a discharge resistor Rc for discharging the electric charge of the snubber capacitor Cs, and includes a series circuit of the snubber capacitor Cs and the snubber resistor Rs, and Each of the discharge resistors Rc is connected in parallel to both ends of the blocking diode BD1.

  On the other hand, VVVF4 is similar to SIV5, and is connected to both ends of a three-phase inverter circuit INV2 and a three-phase inverter circuit INV2 in which a plurality (three in the example of FIG. 1) of a pair of upper and lower arms (switching elements) connected in series are connected in parallel. A filter capacitor FC2 connected in parallel to the (DC side terminal), a switch SW2 for electrically disconnecting the overhead line 1 and the three-phase inverter circuit INV2, and a three-phase inverter circuit together with the filter capacitor FC2 connected in series to the switch SW2. The propulsion motor 7 is driven by supplying the output of the three-phase inverter circuit INV2 to the propulsion motor 7 and having a filter reactor FL2 that smoothes the input voltage to the INV2.

  In the example of FIG. 1, an application example of a DC overhead wire to an electric vehicle is shown, but also in an AC overhead wire electric vehicle, an AC input is converted into DC power by a converter and accumulated in a smoothing capacitor. The configuration and operation of a circuit portion that converts electric power to AC power again by a three-phase inverter circuit are the same or equivalent. For this reason, the same application is possible also to the electric vehicle of an AC overhead wire.

  Further, in the configuration of FIG. 1, the filter reactors (FL1, FL2) are provided in each of the VVVF 4 and SIV 5, but a configuration in which these filter reactors FL1, FL2 are shared is also possible.

(Role of blocking diode)
Next, the role of the blocking diode will be described with reference to FIGS.

  FIG. 2 shows a normal operation state of the circuit shown in FIG. 1, in which the pantograph 2 comes into contact with the overhead wire 1 and a current flows from the overhead wire 1 to the SIV 5 via the pantograph 2, and the three-phase inverter circuit INV1 of the SIV 5 Electric power is supplied to the load 10 in the vehicle via. Similarly, current flows through the pantograph 2 to the VVVF 4, electric power is supplied to the propulsion motor 7, and the vehicle is controlled to be in an accelerated state.

FIG. 3 is a diagram illustrating an operation state when the blocking diode BD1 is not provided from the configuration of FIG. For example, when the overhead wire 1 and the pantograph 2 are separated from each other in the state of FIG. 2 (hereinafter referred to as “separated wire”), power is supplied to the propulsion motor 7 by discharging the charge accumulated in the filter capacitor FC2 of the VVVF4. The power supply to the load 10 is supplied by releasing the electric charge stored in the filter capacitor FC1 of SIV5. The power supply to the propulsion motor 7 is continued until the voltage V _FC2 of the filter capacitor FC2 decreases to fall below the allowable operating range and power supply cannot be performed. At this time, the electric charge of the filter capacitor FC1 of SIV5 is also supplied to the propulsion motor 7 which is the load of VVVF4. Therefore, the voltage V _FC1 of the filter capacitor FC1 of SIV5 rapidly decreases in order to supply power to the VVVF4 side.

  On the other hand, as SIV5, even if a disconnection occurs, operation must be continued and power supply to the load 10 must be continued. In order for the SIV 5 to continue operation during the disconnection period, it is necessary to prepare a filter capacitor FC1 having a large capacity in anticipation of the amount of power supplied to the VVVF4 side.

  On the other hand, FIG. 4 is a diagram illustrating an operation state when the blocking diode BD1 is present. For example, in the state of FIG. 2, when the pantograph 2 is disconnected from the overhead line 1, the charge discharge from the filter capacitor FC1 of the SIV5 to the VVVF4 side is blocked by the blocking diode BD1, so the filter capacitor FC1 of the SIV5 In this case, the charge is discharged only on the load 10 side of the SIV5. Therefore, the SIV 5 does not need to consider the power supply to the VVVF 4 side, and the filter capacitor FC1 can be downsized. For these reasons, the blocking diode BD1 is installed in the SIV5.

(Recovery operation of blocking diode in the prior art)
FIG. 5 is a schematic circuit diagram for explaining the recovery operation of the blocking diode BD1 in the prior art. FIG. 6 is a time chart for explaining the recovery operation of the blocking diode BD1 in the prior art. These figures show, for example, an overhead voltage in a state where DC power is supplied from the overhead line 1 to the three-phase inverter circuit INV1 of the SIV5 via the pantograph 2 and power is supplied from the three-phase inverter circuit INV1 to the load 10. The operation in the case where E _S suddenly drops about several hundred volts is shown.

As shown in FIG. 5, when the current i _SIV flows from the overhead line 1 via the pantograph 2 through the path of the filter reactor FL1, the blocking diode BD1, the three-phase inverter circuit INV1, and the load 10, the abrupt change in the overhead voltage E _S If you suddenly falls trolley voltage E _S by (when migrating "period-a 'from the" period-B "), in a moment of time, the filter capacitor voltage overhead line voltage E _S is charged to the filter capacitor FC1 It becomes lower than V _FC1 (see FIG. _6A ). Therefore, at the time of the overhead line changes suddenly, the blocking diode BD1, the differential voltage V _r of the overhead wire voltage E _S and the filter capacitor voltage V _FC1 is applied as reverse voltage (see Figure 6 (b)). At this time, a voltage in the reverse direction is applied to the blocking diode BD1 from the state in which a current flows in the forward direction. For this reason, the recovery current irr in which the current flows in the reverse direction flows through the blocking diode BD1 for a moment (see FIG. 6C). The surge voltage ΔV _S generated by the product of the current change rate di / dt when the recovery current irr disappears and the inductance of the circuit (that is, the sum of the inductance component of the filter reactor FL1 and the floating inductance component of the circuit) is Superimposed on Vr, eventually, a voltage of ΔV _S + Vr = Vrr is applied in the reverse direction of the blocking diode BD1 (see FIG. 6B).

(Recovery operation when Si diode is used as blocking diode)
FIG. 7 is a simplified circuit diagram for explaining a recovery operation when a Si diode is used as the blocking diode BD1. FIG. 8 is a time chart showing a detailed operation state of the recovery operation when a Si diode is used as the blocking diode BD1.

First, in Period- (1), when the current i _SIV flows from the overhead line 1 through the filter reactor FL1 to the blocking diode BD1 in the forward direction, the overhead line 1 suddenly changes and the overhead line voltage E _S rapidly decreases. Thus, the overhead line voltage E _S <filter capacitor voltage V _FC1 , and the current i _SIV flowing in the forward direction of the blocking diode BD1 decreases during the period of Period− (2). At this time, the current i _SIV has a slope of −di / dt (1) determined by the relationship between the magnitude of the difference voltage between the filter capacitor voltage V _FC1 and the overhead wire voltage E _S and the inductance component existing in the current path. After decreasing and falling below 0 (A), the recovery current irr increases in the negative direction with the same slope of −di / dt (1) (di / dt = (filter capacitor voltage V _{FC1 −overhead} voltage) E _S ) / (inductance component of filter reactor FL1 + inductance component of stray inductance PL1) = (V _FC1 −ΔE _S ) / (L1 + L2)).

After the recovery current irr reaches a peak (negative peak), it starts decreasing and becomes 0 (A) with a slope of + di / dt (2) (Period− (3)). At this time, a counter electromotive voltage V _S = + (di / dt (2)) × (L1 + L2) is generated by the product of + di / dt (2) and the inductance component in the circuit. On the other hand, after a sudden change of the overhead wire voltage E _S, the filter capacitor voltage V _FC1, the value is reduced slightly by the charge released in a period of Period- (2). If the difference between the filter capacitor voltage V _FC1 and the overhead wire voltage E _{S at} this time is ΔE _S ′, the voltage Vrr applied in the reverse direction of the blocking diode BD1 is Vrr = ΔE _S ′ + V _S.

(Circuit operation when equipment other than SIV5 is grounded)
For example, as shown in FIG. 9, when the DC bus is grounded on the other side (for example, VVVF4) 11 other than SIV5 connected in parallel to SIV5, the overhead line voltage E _S suddenly becomes 0 (V ). At this time, as described with reference to FIG. 7 and FIG. 8, the recovery operation phenomenon of blocking diodes BD1, backward applied voltage Vrr blocking diode BD1, as shown in FIG. 10, the Vrr = E _S + V _S.

Here, the blocking diode BD1 must have a sufficiently high breakdown voltage so as not to be broken at a voltage of Vrr. It is necessary to select a diode having a higher breakdown voltage as the back electromotive voltage V _S is higher. It is necessary to design so as not to break even in an external abnormal state such as the ground fault as described above. For this reason, in the circuit design of SIV5 having the blocking diode BD1, it is necessary to consider that the back electromotive voltage V _S is as small as possible.

(Operation of snubber circuit in the prior art)
As described above, reducing the back electromotive voltage V _S greatly affects the selection of the blocking diode BD1. On the other hand, the back electromotive voltage V _S can be reduced by reducing (+ di / dt (2)), which is the current change rate after recovery, as much as possible.

FIG. 11 is a circuit diagram for explaining the effect of the snubber circuit, and FIG. 12 is a time chart for explaining the effect of the snubber circuit. In FIG. 12, the waveform indicated by the thick solid line is the current (i _SIV ) and voltage (V _BD1 ) when no snubber circuit is provided. As shown in FIG. 11, by connecting the snubber capacitor Cs in parallel to the blocking diode BD1, the recovery current ir is shunted to the snubber capacitor side simultaneously with the reverse direction of the blocking diode BD1 (ills shown). By this action, + di / dt (2) (solid line waveform in FIG. 12) at the time of recovery determined by the diode characteristics of the blocking diode BD1 is the inductance component of the snubber capacitor Cs and the circuit (inductance component L1 of the filter reactor FL1 + floating) It becomes + di / dt (3) (a broken line waveform in FIG. 12) determined by resonance with the inductance component L2) of the inductance PL1. At this time, by selecting a snubber capacitor Cs having a sufficiently large capacity with respect to the charge amount that determines the recovery characteristic of the blocking diode BD1, the value of + di / dt (3) is set to be greater than the value of + di / dt (2). Can also be made extremely small (di / dt (2) >> di / dt (3)). As a result, the counter electromotive voltage V _S determined by the product of di / dt and the inductance component in the circuit is the counter electromotive voltage V _S (2) with the snubber circuit and the counter electromotive voltage V _S (3) without the snubber circuit. The relationship V _S (2) >> V _S (3) can be generated between the two. Thus, by providing the snubber capacitor Cs, the back electromotive voltage V _S can be reduced, and a reasonably reasonable withstand voltage can be selected for the blocking diode BD1.

  In the snubber circuit of the present embodiment, resonance with the filter reactor FL1 is sustained only by the snubber capacitor Cs. Therefore, as shown in FIGS. 1 and 11, a snubber resistor Rs is provided in series with the snubber capacitor Cs. It is arranged so that resonance does not continue. Further, in order to discharge the electric charge of the snubber capacitor Cs after the snubber capacitor Cs is charged, the discharge resistor Rc is arranged in parallel with the series circuit of the snubber capacitor Cs and the snubber resistor Rs. In addition, when there is no discharge resistance Rc, the charge of the snubber capacitor Cs is blocked by the blocking diode BD1 and cannot be discharged.

(Prior art issues)
The conventional SIV is configured as described above, and the conventional technique uses a silicon-based plain diode (planar diode), and thus has a large recovery current. For this reason, in order to make the withstand voltage of the blocking diode reasonable, it is necessary to connect a large snubber capacitor to suppress the surge voltage generated by the recovery current. In addition, the discharge resistance for discharging the charge stored in this type of snubber capacitor has also increased according to the capacity and size of the snubber capacitor.

  In SIV, forward current always flows through the blocking diode during normal operation, and energization loss always occurs. For this reason, the blocking diode has been a factor of reducing the efficiency of SIV. Furthermore, in SIV, a cooler that cools the blocking diode in addition to the snubber circuit is required, which has been a factor in increasing the size and cost of the device.

  On the other hand, in order to reduce or omit the snubber circuit, a blocking diode having a very high breakdown voltage with respect to the overhead line voltage is required. In this case, there is a disadvantage that the diode is expensive. . Further, when this type of diode is used, the forward voltage also increases, and there is a problem that energization loss increases. Therefore, the use of a high-breakdown-voltage blocking diode leads to an increase in the cost of the diode, an increase in the size of the cooler, an increase in energization loss, and the advantage that the snubber circuit can be omitted at all.

  In addition, if a silicon (silicon: Si) -based Schottky barrier diode is used, the forward voltage is reduced and the conduction loss can be reduced. However, since a silicon Schottky barrier diode cannot have a high breakdown voltage, in order to apply it to a high-voltage application such as a 750V overhead line or a 1500V overhead line as an application for a railway vehicle, the diode elements are parallelized and serialized. Is inevitable, resulting in an increase in the size and cost of the apparatus and an increase in loss.

(The gist of the embodiment of the present application and its technical description)
In order to solve the various problems and restrictions described above, in this embodiment, a Schottky barrier diode based on silicon carbide (SiC) is applied to the SIV blocking diode. Here, the SiC Schottky barrier diode has a forward voltage lower than that of the silicon planar diode, can reduce the conduction loss, and ideally no recovery current flows, so the snubber circuit can be made smaller or omitted. You can do it.

  FIG. 13 is a simplified circuit diagram for explaining a recovery operation when a SiC Schottky barrier diode is used as a blocking diode. FIG. 14 is a time chart showing a detailed operation state of the recovery operation when the SiC Schottky barrier diode is used as a blocking diode.

First, as shown in FIG. 14, from the blocking diode BD1 through the pantograph 2 from the overhead wire 1 has a forward current flows Period- (1), due to the overhead wire sudden change trolley voltage E _S decreased rapidly Period- ( The operation up to 2) is the same as that described in the section of the prior art. On the other hand, when the SiC Schottky barrier diode is used, the recovery current does not flow after the SIV current becomes 0 (A) at the end of Period- (2) (see FIG. 13). The applied reverse direction voltage Vrr is the difference voltage between the overhead line voltage E _S and the filter capacitor voltage V _FC1 after Period− (2), that is, the reverse direction applied voltage Vrr is Vrr≈Vr = E _S −V _FC1 It becomes only.

More specifically, for example, even if the overhead line voltage E _S suddenly becomes 0 (V) due to a ground fault of the bus other than the SIV, ideally the overhead line voltage E _S is applied to the blocking diode BD1. because not applied voltages above the breakdown voltage of the blocking diode BD1 may be higher slightly relative to the overhead line voltage E _S.

  Therefore, if a SiC Schottky barrier diode is used as the blocking diode BD1, a snubber circuit composed of the snubber capacitor Cs, the snubber resistor Rs, and the discharge resistor Rc is ideally unnecessary. Note that a slight surge voltage may occur due to the influence of floating capacitance on the circuit. For this reason, a snubber circuit may be necessary depending on the circuit configuration and the characteristics of the SiC Schottky barrier diode. Even in such a case, the snubber circuit, that is, the snubber capacitor Cs and the snubber resistor may be used. The size and capacity of Rs can be reduced.

(Effects of the present embodiment)
As described above, according to the auxiliary power supply for a vehicle of the present embodiment, a blocking diode for preventing a backflow from the inverter circuit side to the overhead line side is provided between the overhead line and the inverter circuit, and SiC is provided in this blocking diode. Since the Schottky barrier diode is applied, an effect that the snubber circuit for protecting the blocking diode can be omitted or can be made as small as possible is obtained.

  Further, by using a SiC Schottky barrier diode as the blocking diode, it is possible to reduce the breakdown voltage of the blocking diode to a level at which a general-purpose product can be selected.

  In addition, since the forward voltage of SiC is lower than that of silicon and the allowable operating temperature is much higher than that of silicon, the heat dissipating fins of the cooler can be made very small, greatly contributing to downsizing and cost reduction of the device. The effect that it can be obtained.

  Note that SiC is an example of a semiconductor referred to as a wide band gap semiconductor, taking into account the characteristic that the band gap is larger than that of Si. In addition to this SiC, for example, a semiconductor formed using a gallium nitride (GaN) -based material or diamond (C) belongs to a wide band gap semiconductor, and their characteristics are also similar to SiC. Therefore, a configuration using a wide band gap semiconductor other than SiC also forms the gist of the present application.

  In the above description, the case where the main circuit of the auxiliary power supply device is a three-phase circuit has been described as an example. Needless to say, the auxiliary power supply device that outputs single-phase alternating current or direct current has the same effect.

  As described above, the auxiliary power supply for a vehicle according to the present invention is useful as an invention that can further reduce the size of the cooler and the snubber circuit provided in association with the blocking diode.

1 Overhead line 2 Pantograph 4 VVVF inverter device (VVVF)
5 Vehicle auxiliary power supply (SIV)
7 Propulsion motor 9 Snubber circuit 10 Load 11 Other equipment BD1 Blocking diode FC1, FC2 Filter capacitor FL1, FL2 Filter reactor INV1, INV2 Three-phase inverter circuit PL1 Floating inductance Cs Snubber capacitor Rc Discharge resistor Rs Snubber resistor SW1, SW2 Switch Tr Transformer

Claims (4)

A vehicle that is mounted on a railway vehicle and includes an inverter circuit that converts DC power or AC power input from an overhead line into desired AC power and supplies it to a load, and is connected in parallel with an inverter device that drives a propulsion motor Auxiliary power supply for
Between the overhead wire and the inverter circuit, a blocking diode that prevents backflow from the inverter circuit side to the overhead wire side is provided,
An auxiliary power supply for a vehicle, wherein the blocking diode is a Schottky barrier diode formed of a wideband semiconductor. A vehicle auxiliary power supply device including an inverter circuit that is mounted on a railway vehicle and converts DC power or AC power input from an overhead line into desired AC power and supplies the load to a load.
Between the overhead wire and the inverter circuit, a blocking diode for preventing a backflow from the inverter circuit side to the overhead wire side is provided,
An auxiliary power supply for a vehicle, wherein the blocking diode is a Schottky barrier diode formed of a wideband semiconductor.   The auxiliary power supply for a vehicle according to claim 1 or 2, wherein a snubber circuit is provided in parallel to the blocking diode.   The auxiliary power supply for a vehicle according to claim 1, wherein the wide band gap semiconductor is a semiconductor using silicon carbide, a gallium nitride-based material, or diamond.

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