JP7637573B2 - Drive system for a rail vehicle and method for installing said drive system - Google Patents

Description

The present invention relates to a drive system for a railway vehicle equipped with a storage battery and a method for installing the drive system.

In recent years, due to the increasing energy density and power density of storage batteries such as lithium-ion batteries, railroad cars equipped with power storage devices that can travel more than 100 km on a single charge have been introduced. In such railroad cars, multiple storage batteries are connected in series and parallel to ensure input power to multiple inverter devices that drive the motors and auxiliary power devices that supply power to vehicle auxiliaries such as air conditioning.

On the other hand, as the number of storage batteries connected in series increases, high insulation performance (e.g., insulation resistance, voltage resistance) is required, which creates the problem of the storage device becoming larger and more expensive.

Patent Document 1 (JP Patent Publication 2016-135030A) describes a technology in which a metal box that houses a battery pack is insulated from the railway vehicle by an insulating material. In this technology, each battery pack box is made of resin and insulated, thereby reducing the insulation performance required for the devices and parts housed in the battery pack box.

JP 2016-135030 A

When supplying power from a storage device to a main conversion device and auxiliary power supply device, which are made up of multiple converter devices and inverter devices, increasing the number of series connections of the storage batteries that make up the storage device requires high insulation performance (e.g., insulation resistance, voltage resistance), which results in the storage device becoming larger and more expensive.

The present invention aims to provide a drive system that can reduce the insulation performance required of the storage device and prevent the storage device from becoming larger and more expensive, even if the number of storage batteries connected in series that make up the storage device increases.

To solve the above problems, one representative driving system for railway vehicles according to the present invention includes multiple converters that output DC voltage converted from AC voltage, multiple inverters that convert the DC voltage output by the converters into three-phase AC voltage to drive an electric motor, and a storage device having a series battery group in which multiple storage batteries are connected in series and performing charging and discharging between the converters or the inverters, and each neutral point provided between each line of the DC lines connecting each of the multiple converters and each of the multiple inverters corresponding to the converters and any inter-battery potential point of the series battery group in the storage device are grounded.

According to the present invention, the insulation performance required for the power storage device is reduced, and therefore it is possible to prevent the power storage device from becoming larger and more expensive in order to ensure the insulation performance.
Furthermore, problems, configurations and effects other than those described above will become apparent from the description of the following embodiments.

1 is a diagram showing an outline of a basic configuration of a railway vehicle equipped with a railway vehicle drive system according to an embodiment of the present invention. FIG. 1 is a diagram showing an example of a configuration in which a drive device according to an embodiment is mounted on an AC electric railcar. FIG. 1 is a diagram showing an example of a configuration in which a drive device according to an embodiment is mounted on a DC electric railcar. 3 is a diagram showing an example of a schematic configuration of a converter device in FIG. 2. 3 is a diagram showing another example of the schematic configuration of the converter device in FIG. 2. FIG. 3 is a diagram showing yet another example of a schematic configuration of the converter device in FIG. 2 . FIG. 4 is a diagram illustrating an example of a schematic configuration of the DC/DC converter device in FIG. 3. FIG. 4 is a diagram showing an example of a schematic configuration of the power storage device in FIGS. 2 and 3 and a connection state with a main converter; FIG. 13 is a diagram showing a current path when the neutral point and the battery potential point are individually grounded. FIG. 13 is a diagram showing a current path when the neutral point and the battery potential point are connected to ground. 11 is a diagram showing a path of a current flowing between two groups in a main converter when a power storage device is not equipped with a reactor. FIG. 1 is a diagram showing a path of a current that flows when a power storage device is charged in a case where the power storage device is equipped with a reactor. FIG. 1 is a diagram showing a schematic configuration of a reactor using individual iron cores. FIG. 1 is a diagram showing a schematic configuration of a reactor having a common core. FIG. 2 is a diagram illustrating an example of an internal configuration of a cutoff device. FIG. 13 is a diagram illustrating another example of the internal configuration of the cutoff device. 11 is a diagram showing a current path when a positive electrode or a negative electrode of a power storage device is short-circuited. 11 is a diagram showing a current path when a positive electrode of a power storage device has a ground fault. FIG. 11 is a diagram showing a current path when a negative electrode of a power storage device has a ground fault; FIG.

Below, with reference to the drawings, an embodiment will be described as a form for carrying out the present invention. Note that the present invention is not limited to this embodiment. Note that in the description of the drawings, the same reference numerals are used for common parts, duplicated explanations are omitted, and components that do not directly affect the present invention (e.g., sensors, controllers, etc.) are omitted.

FIG. 1 is a diagram showing an outline of the basic configuration of a railway vehicle equipped with a railway vehicle traction system according to an embodiment of the present invention.
The basic configuration shown in FIG. 1 is a vehicle 1a equipped with a drive device 21 according to the present invention and a vehicle 1b not equipped with a drive device.

Car 1a is supported on rails 11 by bogie 2a with wheels 3a and 3b, and bogie 2b with wheels 3c and 3d. Car 1b similarly has bogie 2c with wheels 3e and 3f, and bogie 2d with wheels 3g and 3h. Cars 1a and 1b are coupled with inter-car couplers 6 to form a train formation. However, the train formation is not limited to the form shown in FIG. 1. It is also possible to operate with only car 1a without coupling car 1b.

FIG. 2 is a diagram showing an example of a configuration in which the drive device 21 according to the embodiment is mounted on an AC electric railcar.
The drive device 21 is composed of a transformer 7, a main converter 8, an electric motor 17, a power storage device 9, an auxiliary power supply device 10 and vehicle auxiliaries 19, and takes in AC power from the overhead line 4 via the current collector 5 into the vehicle.

The transformer 7 transforms the AC power taken in by the collector 5 to an appropriate voltage value and outputs it to the main converter 8.

The main conversion device 8 is composed of a converter device 14 and an inverter device 15, and performs the required power conversion to drive the electric motor 17. Of these, the converter device 14 converts the AC voltage input from the transformer device 7 into a DC voltage, and the inverter device 15 converts the DC voltage converted by the converter device 14 into the required three-phase AC voltage to drive the electric motor 17.

The storage device 9 is connected to the DC line of the main conversion device 8, and is charged using the output power of the converter device 14 and regenerative power from the inverter device 15, allowing it to be discharged at any time.

The auxiliary power supply 10 is connected to the DC line of the main converter 8, converts DC power to AC power, and supplies the AC power to vehicle auxiliaries 19, such as the air conditioning system and lighting inside the vehicle.

FIG. 3 is a diagram showing an example of a configuration in which the driving device 21 according to the embodiment is mounted on a DC electric railcar.
The drive device 21 is composed of a DC/DC converter device 36, an inverter device 15, an electric motor 17, a power storage device 9, an auxiliary power supply device 10 and vehicle auxiliaries 19, and takes in DC power from the overhead line 4 through the current collector 5 into the vehicle.

The DC/DC converter device 36 transforms the DC voltage input from the current collector device 5 into an appropriate DC voltage value and inputs it to the inverter device 15, the storage device 9, and the auxiliary power supply device 10. The rest of the configuration is the same as that shown in FIG. 2, so a description is omitted.

The converter device 14 shown in FIG. 2 has a neutral point potential on the output side, and the voltage applied to the transformer device 7 can be controlled by a switching element (not shown) that constitutes the converter device 14 (switching element 26 shown in FIGS. 4 to 6).

The DC/DC converter device 36 shown in FIG. 3 is insulated between the overhead line side (hereinafter referred to as the "primary side") and the inverter device side (hereinafter referred to as the "secondary side"), has a neutral potential on the secondary side, which corresponds to the output side, and is capable of supplying power in both directions.

Next, configuration examples of the converter device 14 are shown in Figures 4 to 6, and a configuration example of the DC/DC converter device 36 is shown in Figure 7.

FIG. 4 is a diagram showing an example of a schematic configuration of the converter device 14 in FIG.
The converter device 14 is composed of two groups, a single-phase three-level converter 14a on the first group side and a single-phase three-level converter 14b on the second group side. Here, the first group and the second group are electrically in parallel, and a plurality of converters are provided to satisfy the required conversion power. However, it is not necessarily required to have a two-group configuration.

Each of the single-phase three-level converters 14a and 14b is composed of capacitors 16a and 16b, a switching element 26, a diode 27, and a ground resistor 37. The capacitors 16a and 16b are connected in series, and their midpoint is grounded as the neutral point 102. Therefore, the upper capacitor 16a has a positive voltage to ground, and the lower capacitor 16b has a negative voltage to ground.

The neutral point 102 of the single-phase three-level converters 14a and 14b is also the connection point between the capacitors 16a and 16b, and is electrically connected via the ground resistor 37 and is connected to the earth 100 and is grounded.

The single-phase three-level converters 14a and 14b switch the switching element 26 on and off to apply a pulsed AC voltage to the transformer 7. The applied voltage has three levels: 0 [V], ±|E| [V], and ±2|E| [V], where |E| is the absolute voltage of each of the capacitors 16a and 16b.

In addition, the single-phase three-level converters 14a and 14b control the voltage applied to the transformer device 7 and generate the DC voltage required for the inverter device 15, the auxiliary power supply device 10, and the storage device 9.

The inverter device 15, which receives the output of the converter device 14, is equipped with one or more circuits that convert DC power to AC power.

FIG. 5 is a diagram showing another example of the schematic configuration of the converter device 14 in FIG.
The configuration of the single-phase three-level converters 14a and 14b shown in Fig. 5 does not require the diode 27 compared to the configuration of the single-phase three-level converters 14a and 14b shown in Fig. 4. Also, in each operation mode of the converter device 14, the number of switching elements and diodes through which current passes is reduced, resulting in high efficiency.

In addition, the configuration of the single-phase three-level converters 14a and 14b shown in FIG. 5 differs from the configuration shown in FIG. 4 as described above, but the grounding state of the neutral point 102, which is also the connection point between the capacitors 16a and 16b, and the voltage applied to the transformer device 7 are the same as in FIG. 4.

FIG. 6 is a diagram showing yet another example of a schematic configuration of the converter device 14 in FIG.
The configuration shown in Fig. 6 can be made smaller than the configurations shown in Fig. 4 and Fig. 5 because the number of switching elements 26 is reduced. The converter device 14 is made up of two groups: a single-phase two-level converter 14c on the first group side and a single-phase two-level converter 14d on the second group side.

The single-phase two-level converters 14c and 14d each include capacitors 16a and 16b, a switching element 26, and a ground resistor 37. The neutral point 102, which is the connection point between the capacitors 16a and 16b of the single-phase two-level converters 14c and 14d, is electrically connected via the ground resistor 37 and is connected to the earth 100 and is grounded.

In addition, the output voltage of the single-phase two-level converters 14c and 14d to the transformer 7 has two levels: 0 [V] and ±2|E| [V], where the absolute voltage of the capacitors 16a and 16b is |E| [V].

FIG. 7 is a diagram showing an example of a schematic configuration of the DC/DC converter device 36 in FIG.
The DC/DC converter device 36 is composed of two groups, a first group DC/DC converter 36a and a second group DC/DC converter 36b. Here, the first group and the second group are electrically in parallel, and a plurality of converters are provided to satisfy the required conversion power. However, it is not necessarily required to have a two-group configuration.

Both DC/DC converters 36a and 36b are composed of capacitors 16a, 16b and 16c, a switching element 26, a transformer 35 and a ground resistor 37.

Capacitors 16a and 16b are connected in series, with their midpoint grounded as the neutral point 102. Therefore, the upper capacitor 16a has a positive voltage to ground, and the lower capacitor 16b has a negative voltage to ground.

The neutral point 102 of the DC/DC converters 36a and 36b is the connection point between the capacitors 16a and 16b, and is electrically connected to the earth 100 via the ground resistor 37 and is grounded.

The DC/DC converters 36a and 36b switch the switching element 26 on and off to apply a pulsed AC voltage to the transformer 35. They control the phase and amplitude of the voltage applied to both sides of the transformer 35 to output a constant voltage to the primary or secondary side.

The inverter device 15, which receives the output of the DC/DC converter device 36, is equipped with one or more circuits that convert DC power into AC power.

FIG. 8 is a diagram showing an example of a schematic configuration of the power storage device 9 in FIGS. 2 and 3 and a connection state with the main converter 8. In FIG.
In a power storage device, a plurality of storage batteries are generally connected in series and parallel, and the power storage device 9 shown in Fig. 8 also has a plurality of storage batteries 23 connected in series and parallel. The positive and negative sides of any one of the series-connected storage batteries 23 at an inter-battery potential point 101 are connected to the storage battery 23 via a fuse 39.

The positive and negative poles of the storage device 9 are connected to the main converter 8 via a reactor 38 and a circuit breaker 30. In addition, the battery potential point 101 is connected to earth 100 via a ground resistor 37 and is grounded.

Each ground resistor 37 is connected to the neutral point 102 of the main converter 8 and the auxiliary power supply 10 and the battery potential point 101 of the storage battery 9. Each ground resistor 37 is electrically connected at one point and then connected to earth 100 and grounded (the auxiliary power supply 10 is not shown in FIG. 8).

FIG. 9 is a diagram showing a current path when the neutral point and the battery potential point are individually grounded.
If each device is individually grounded, a current flows to the earth 100. This current is generated when the voltages between the positive and negative poles momentarily differ due to the switching operation of the main converter 8 and the auxiliary power supply 10, or due to variations in the characteristics of the capacitors 16a and 16b and the storage battery 23. As a result, the current contains high-frequency components.

The earth 100 is electrically connected to the box housing that houses the drive unit 21 and to the vehicle 1a. If a current containing high-frequency components flows, electromagnetic noise may adversely affect signaling equipment on the ground.

FIG. 10 is a diagram showing a current path when the neutral point and the potential point between the storage batteries are connected and grounded.
By using the configuration shown in FIG. 8, no current flows through earth 100 in an ideal state, as shown in FIG.

In reality, even in the case shown in FIG. 10, a small current flows through earth 100, but it is smaller than in the case shown in FIG. 9, and is further reduced by ground resistor 37.

The reactor 38 provided in the storage device 9 is intended to prevent inrush current and smooth the charge/discharge current, and in the configuration shown in Figure 8, it also prevents unnecessary current from flowing between the two groups in the main converter 8.

Figure 11 also shows the current paths that flow between the two groups in the main converter 8 when the storage device 9 does not have a reactor 38.

When a potential difference occurs between the positive side capacitor 16a of the first group converter 14a and the second group converter 14b, a current flows in the path indicated by the dotted arrow in Figure 11. When a potential difference occurs between the negative side capacitor 16b of the first group converter 14a and the second group converter 14b, a current flows in the path indicated by the dashed line arrow in Figure 11. The current also flows from the group with the higher voltage to the group with the lower voltage.

The current shown in FIG. 11 is a state in which a current intended to charge and discharge the storage device 9 flows to the other group due to a potential difference between the groups. This current therefore causes a power loss.

Figure 12 shows the current paths that flow when the storage device 9 is charged when reactors 38 are installed between the converters 14a and 14b and the positive and negative electrodes of the storage device 9, respectively.

The charging current generates a magnetic field inside the reactor 38, which causes the reactor 38 to have high impedance to currents in the opposite direction to the charging current. This prevents current from flowing between groups, and reduces power loss. In addition, the ground resistor 37 can always suppress the current flowing between groups, regardless of the state of the reactor 38.

Next, the configuration of the reactor 38 will be described.
Since substantially the same current flows through the positive and negative poles of the reactor 38, the reactor is magnetically coupled to achieve miniaturization.

FIG. 13 is a diagram showing a schematic configuration of a reactor 38 using individual iron cores 42. As shown in FIG.
This corresponds to a typical case in which the reactor 38 is configured with coils each having an iron core 42 on the positive and negative sides.

On the other hand, FIG. 14 is a diagram showing a schematic configuration of a reactor 38 in which the iron core 42 is made common.
The reactor 38 is configured by winding two windings, one for the positive pole side and one for the negative pole side, around one iron core 42. Therefore, the positive pole side and the negative pole side coils are magnetically coupled.

The configuration shown in FIG. 14 can be made smaller than the configuration shown in FIG. 13 because it has only one iron core 42. The positive and negative windings are connected to the storage battery 23 and the main converter 8 so that the current flows in a direction that reinforces the magnetic flux in the iron core.

The configuration of the cutoff device 30 will now be described.
In order to prevent a situation in which only the positive side or only the negative side is charged or discharged with respect to the neutral point 102, resulting in a voltage mismatch, the positive side and the negative side of the circuit breaker 30 need to operate in conjunction with each other.

15 and 16 are diagrams each showing an example of the internal configuration of the cutoff device 30. As shown in FIG.
15 shows a configuration in which a circuit breaker 30a having a plurality of main contacts 43 is used as the circuit breaker 30. The two main contacts 43 are operated when a voltage is applied to an operating coil 44. An operating relay 45 switches between application and non-application of a voltage to the operating coil 44. Each of the two main contacts 43 is connected to a respective DC line of the main converter 8 (see FIG. 8).

Figure 16 shows a configuration in which two circuit breakers, 30b and 30c, are used as the circuit breaker 30, and the auxiliary contact 46 of the circuit breaker 30c is connected to the operating coil 44 of the circuit breaker 30b. When the operation relay 45 is turned on to apply a voltage to the operating coil 44 of the circuit breaker 30c, the main contact 43 and auxiliary contact 46 of the circuit breaker 30c operate in conjunction with each other. The operation of the auxiliary contact 46 switches between applying and not applying a voltage to the operating coil 44 of the circuit breaker 30b, and the main contact 43 of the circuit breaker 30b operates in conjunction with the main contact 43 of the circuit breaker 30c. The main contacts 43 of the circuit breakers 30b and 30c are each connected to the DC line of the main converter 8 (see Figure 8). .

The circuit breaker 30 shown in FIG. 15 can be made compact because it can be configured with a single circuit breaker, but it is limited to circuit breakers with multiple main contacts, so it may not be possible to select a circuit breaker with optimal specifications.

The circuit breaker 30 shown in FIG. 16 uses multiple circuit breakers, so it is larger than the configuration shown in FIG. 15, but since it only requires one or more main contacts, all circuit breakers can be selected. The operating relay 45 is operated by control in the drive unit 21.

Furthermore, the fuse 39 shown in FIG. 8 is configured to be able to cut off the current when the storage device 9 experiences an internal short circuit or a ground fault.

Figure 17 shows the current path when the positive or negative electrode of the storage device 9 is short-circuited. Current flows through the short-circuited point 40, but can be cut off by the fuse 39.

Figure 18 is a diagram showing the current path when a ground fault occurs at the positive electrode of the storage device 9. Current flows through the ground fault location 41, but can be cut off by the fuse 39 (indicated by an x in Figure 18). Figure 19 is a diagram showing the current path when a ground fault occurs at the negative electrode of the storage device 9. Current flows through the ground fault location 41, but can be cut off by the fuse 39 (indicated by an x in Figure 19).

In addition, in Figures 18 and 19, ground resistor 37 suppresses the current value to prevent equipment failure caused by the current that flows before fuse 39 is cut off. Furthermore, even in ground fault locations 41 other than those shown in Figures 18 and 19, the current always passes through fuse 39, making it possible to cut off the fault. However, this is based on the assumption that a sufficient current flows for fuse 39 to cut off the fault in the event of a short circuit or ground fault.

The storage batteries 23 provided in the power storage device 9 are common to the first and second groups, which allows for a reduction in the number of wiring connections. Also, if the storage batteries 23 are independent for each group, it would be necessary to implement an equal number of storage batteries 23 in each group, but if they are common to the groups, the number of storage batteries 23 can be optimized.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications are possible without departing from the gist of the present invention.

1a, 1b...vehicles, 2a, 2b, 2c, 2d...bogies,
3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h...wheels, 4...overhead wire, 5...current collector,
6... inter-car coupler, 7... transformer, 8... main converter, 9... power storage device, 10... auxiliary power supply device,
11... rail, 14... converter device, 14a, 14b... single-phase three-level converter,
14c, 14d... single-phase two-level converter, 15... inverter device,
16a, 16b, 16c...capacitor, 17...motor, 19...vehicle auxiliary device,
21: Drive device; 23: Storage battery; 26: Switching element; 27: Diode;
30... circuit breaker; 30a, 30b, 30c... circuit breaker; 35... transformer;
36...DC/DC converter device, 36a, 36b...DC/DC converters,
37: ground resistor, 38: reactor, 39: fuse, 40: short circuit location,
41: ground fault location; 42: iron core; 43: main contact; 44: operating coil; 45: operating relay;
46: auxiliary contact, 100: earth, 101: battery potential point, 102: neutral point

Claims (12)

A plurality of converters that convert AC voltages and output DC voltages;
a plurality of inverters that convert the DC voltage output by the converter into a three-phase AC voltage to drive an electric motor;
a power storage device having a series-connected battery group in which a plurality of batteries are connected in series, and performing charging and discharging between the battery group and the converter or the inverter;
a neutral point provided between each of the DC lines connecting each of the plurality of converters and each of the plurality of inverters corresponding to the converter, and any inter-battery potential point of the group of series batteries in the power storage device are grounded. 2. A drive system for a rail vehicle according to claim 1,
11. A traction system for a railway vehicle, wherein each of the neutral points is a midpoint of a series circuit of a plurality of capacitors provided between each of the DC lines. A drive system for a railway vehicle according to claim 1 or 2,
13. A traction system for a railway vehicle, wherein the neutral point and the inter-battery potential point are each connected via a resistor to ground. A drive system for a railway vehicle according to any one of claims 1 to 3,
a positive electrode and a negative electrode of the power storage device are connected to a positive electrode side and a negative electrode side of each of the DC lines via reactors, respectively. 5. A drive system for a rail vehicle according to claim 4,
a reactor connected to the positive electrode of the power storage device and a reactor connected to the negative electrode of the power storage device, the reactor being magnetically coupled to each other; A drive system for a railway vehicle according to any one of claims 1 to 5,
A traction system for a railway vehicle, characterized in that the positive and negative electrodes of the storage device are connected to the positive and negative sides of the DC lines via circuit breakers, respectively. 7. A drive system for a rail vehicle according to claim 6,
A drive system for a railway vehicle, characterized in that the circuit breaker connected to the positive electrode of the storage device and the circuit breaker connected to the negative electrode of the storage device are composed of a single circuit breaker having a plurality of main contacts. 7. A drive system for a rail vehicle according to claim 6,
A drive system for a railway vehicle, characterized in that the circuit breaker connected to the positive electrode of the storage device and the circuit breaker connected to the negative electrode of the storage device have a structure in which an auxiliary contact linked to one of the main contacts is connected to an operating coil of the remaining main contact. A drive system for a railway vehicle according to any one of claims 1 to 8,
A traction system for a railway vehicle, characterized in that fuses are provided between the inter-battery potential point and the series battery group on the positive electrode side of the storage device, and between the inter-battery potential point and the series battery group on the negative electrode side of the storage device. a plurality of converters that convert an AC voltage into a DC voltage and output the DC voltage; a plurality of inverters that convert the DC voltage output by the converters into a three-phase AC voltage to drive an electric motor; and an electric storage device having a series storage battery group in which a plurality of storage batteries are connected in series and performing charging and discharging between the series storage battery group and the converters or the inverters, the electric storage device being mounted on a railway vehicle as a drive system;
a neutral point provided between each of the DC lines connecting each of the plurality of converters and each of the plurality of inverters corresponding to the converter, and any inter-battery potential point of the group of series batteries in the power storage device are grounded. 11. A method for installing a drive system for a rail vehicle according to claim 10, comprising the steps of:
a series circuit of a plurality of capacitors provided between the DC lines and each of the intermediate points of the series circuit is grounded as each of the neutral points. 12. A method for installing a drive system for a rail vehicle according to claim 10 or 11, comprising the steps of:
A method for installing a traction system for a railway vehicle, comprising the steps of: connecting each of the neutral points and the inter-battery potential point via a resistor to ground.

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