JP2024099375A - Drive system and method for rail vehicles - Google Patents

Abstract

To achieve high safety by continuously supplying electric power to an auxiliary machine even when switching a plurality of storage batteries mounted on a storage battery-driven railroad train between series-connection and parallel-connection alternately.SOLUTION: A storage battery device comprises: a first shut-off tool that has a plurality of storage batteries and a switching part that switches between series-connection and parallel-connection of the plurality of storage batteries, and that shuts off electric power from a train wire to a DC link; a first electric power converting part that converts electric power from the DC link to electric power for driving a motor; a second electric power converting part that converts electric power from the DC link to electric power for charging the storage battery device; a third electric power converting part that converts electric power inputted from the DC link or the storage battery device to electric power for driving an auxiliary machine; a filter capacitor that is connected to an input side of the third electric power converting part; a second shut-off tool that shuts off electric power supplied from the storage battery device to the DC link; and first and second rectifying parts through which electric power is passed in a direction of the third electric power converting part, from the DC link and the storage battery device, where output points at the third electric power converting part side of the first and second rectifying parts are connected to positive electrodes of the filter capacitor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drive system and drive method for a railway vehicle equipped with a storage battery device that can switch the connection state of multiple storage batteries between series and parallel.

Regarding railway vehicles equipped with a storage battery device capable of switching between series and parallel connections, the following background art is provided.
Patent Document 1 states, "...the vehicle includes a converter, an inverter, a pair of DC links, a plurality of storage battery modules, a step-down chopper, and a switching circuit unit. The converter is configured to be capable of converting single-phase AC power into DC power. The inverter is configured to be capable of converting DC power into three-phase AC power. The pair of DC links connect a DC input/output side of the converter to a DC input/output side of the inverter. The plurality of storage battery modules are electrically connected to the pair of DC links. The step-down chopper is provided between a positive DC link of the pair of DC links and positive sides of the plurality of storage battery modules." and is configured to be able to step down the DC power output from the positive DC link to the positive side of the multiple storage battery modules. The switching circuit unit switches the electrical connection relationship of the multiple storage battery modules between series and parallel in an AC power supply section receiving single-phase AC power from an AC system, a DC power supply section receiving DC power from a DC system, and an unpowered section receiving no power supply from the outside, and switches the electrical connection relationship between the pair of DC links, the multiple storage battery modules, and the step-down chopper. (Paragraph 0005 describing "Means for solving the problem")

Patent Document 2 describes a technology that "...the power storage system is composed of a battery unit, a first contactor, and a control unit. The battery unit has multiple secondary batteries whose connection pattern with other secondary batteries can be switched between series connection and parallel connection, and supplies power to a traction power conversion device that converts first AC power supplied via a secondary winding of a transformer that steps down power from an overhead line into traction power for driving a traction motor that runs the electric vehicle and supplies the power to the traction motor, and to a DC load mounted on the electric vehicle. The first contactor is provided midway along the power line connecting the battery unit and the traction power conversion device, and switches between a state in which power is cut off and a state in which power is conducted. When the electric vehicle is in a predetermined state and the first contactor is switched to a state in which power is conducted, the control unit supplies power to the traction power conversion device by switching the connection pattern of the multiple secondary batteries to a series connection." (Paragraph 0005 describing "Means for solving the problem")

JP 2017-112795 A JP 2017-225323 A

The inventors have conducted extensive research into a traction system for a railway vehicle equipped with a storage battery device capable of being switched between series and parallel connections, and have come to the following findings.
Patent Literature 1 discloses that by switching the electrical connection relationship of multiple storage battery modules between series and parallel, and by switching the electrical connection relationship between a pair of DC links, multiple storage battery modules, and a step-down chopper, it is possible to travel in AC electrified sections, DC power supply sections, and non-power supply sections while omitting a step-up chopper. However, Patent Literature 1 does not disclose an auxiliary power conversion device and auxiliary machines as on-board equipment, and does not mention the supply of power to the auxiliary power conversion device and auxiliary machines when switching the electrical connection relationship of the multiple storage battery modules.

Here, when an auxiliary power conversion device and an auxiliary are mounted on a railway traction system equipped with a storage battery device that can be switched between series and parallel, the following problems may occur.
When operating a storage battery equipment that can be switched between series and parallel, it is necessary to disconnect the storage battery equipment from the main circuit when switching the connection relationship of the storage battery equipment from the viewpoint of safety. When the storage battery equipment is reconnected to the main circuit after switching, a large current may be generated from the storage battery equipment to the overhead line or from the overhead line to the storage battery equipment due to the voltage difference between the storage battery equipment and the overhead line. Therefore, when connecting the storage battery equipment to the main circuit, it is necessary to disconnect the overhead line from the main circuit. In other words, the power supply to the main circuit is interrupted from the time the main circuit is disconnected from the overhead line to the time the storage battery equipment is connected to the main circuit, and therefore the power supply to the auxiliary equipment is interrupted.

Patent Document 2 also discloses a technology for a railway vehicle equipped with a DC load, such as electronic devices (excluding the running motor), and a storage battery unit that can be switched between series and parallel and that in principle supplies power to the DC load, in the event of an emergency on the railway vehicle, that can supply power from the storage battery unit to the DC load and the running motor.

However, the technology disclosed in Patent Document 2 is designed for emergencies, and so when the vehicle normally travels in a non-overlapping section where the DC load and the traction motor are driven by power from a storage battery, the following two problems can be considered.
First, when supplying power to both a DC load and a traction motor, the battery unit is divided into a first group that supplies power to the DC load in a parallel state, and a second group that supplies power to the traction motor in a series state. As a result, the connection relationship of the battery as a whole is not switched to series-parallel, and a large battery capacity is required that can cover the combined power of the DC load and the traction motor.

Secondly, the power from the overhead line to the DC load is split into two systems, with the system for the running windings using high voltage to drive the running motor, and the system for the load windings using low voltage to charge the battery unit, drive the DC load, and drive the AC load. This requires more windings and power conversion devices than when a single system of power from the overhead line is used to drive the running motor, charge the battery unit, and drive the DC load. This limits the space available for installing batteries and other equipment. Furthermore, although charging the battery unit with the low voltage of the load winding is sufficient for emergency operation of a small battery unit, it is not suitable for railway vehicles that are normally equipped with large battery units for running on non-overhead sections.

The present invention aims to provide a technology for a drive system for railway vehicles equipped with a storage battery device that can be switched between series and parallel connections, which drives the motor, charges and discharges the storage battery device, and drives the auxiliary devices through a single DC link, and which continuously supplies power to the auxiliary devices even when the connection state of the storage battery device is switched between series and parallel.

In order to solve the above problems, one representative traction system for railway vehicles of the present invention is a railway vehicle equipped with a storage battery device, the storage battery device having a plurality of storage batteries and a switching unit that switches the plurality of storage batteries between a series connection and a parallel connection, and includes a first circuit breaker that cuts off the power supplied from the electric power line to a DC link in the railway vehicle, a first power conversion unit that converts the power input from the DC link into power to drive an electric motor, a second power conversion unit that converts the power input from the DC link into power to charge the storage battery device, and a DC The system includes a third power conversion unit that converts the power input from the link or the storage battery device into power to drive the auxiliary equipment, a filter capacitor connected to the input side of the third power conversion unit, a second circuit breaker that cuts off the power supplied from the storage battery device to the DC link, a first rectification unit that passes power from the DC link to the third power conversion unit, and a second rectification unit that passes power from the storage battery device to the third power conversion unit, and the output points of the first rectification unit and the second rectification unit on the third power conversion unit side are connected to the positive pole side of the filter capacitor.

According to the present invention, in a traction system for railway vehicles that utilizes a storage battery device that can be switched between series and parallel connections, the electric motor is driven, the storage battery device is charged and discharged, and the auxiliary equipment is driven through a single DC link, and power is continuously supplied to the auxiliary equipment even when the connection state of the storage battery device is switched between series and parallel.This reduces the number of devices such as power conversion devices, expands the installation space for the storage battery and other equipment, while continuously driving the auxiliary equipment and achieving greater safety for passengers.
Problems, configurations and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention.

FIG. 1 is a diagram showing a configuration of a battery-powered driving system according to an embodiment. FIG. 2 is a diagram showing the circuit configuration of a battery-powered drive system in a catenary running mode. FIG. 2 is a diagram showing a circuit configuration of a battery-powered drive system in a battery driving mode. 1 is a diagram showing an example of a flowchart for switching the battery configuration of a battery-powered drive system from a parallel connection to a series connection (overhead wire running mode → battery running mode). 1 is a diagram showing an example of a flowchart for switching the battery configuration of a battery-powered drive system from series connection to parallel connection (battery running mode → overhead line running mode). FIG. FIG. 2 is a diagram showing the circuit configuration of a battery-powered drive system in a DC train mode.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, in the drawings, the same parts are denoted by the same reference numerals.

FIG. 1 is a diagram showing the configuration of a battery-powered driving system according to an embodiment of the present invention.
The battery-powered drive system is a system for controlling the drive of a railway motor in both electrified and non-electrified sections. Specifically, the components of this system are mainly a current collector 1, a switch (high-speed circuit breaker for current collector) 2, a power conversion unit (inverter) 3a, a filter capacitor for the inverter 3b, a motor 4, a power conversion unit (SIV) for auxiliary equipment 5a, a filter capacitor for the SIV 5b, an auxiliary load 6, a power conversion unit (DC/DC converter) 7a, a filter capacitor for the DC/DC converter 7b, power storage devices 8a and 8b, switches (contactors) 9a, 9b, 9c, 9d and 9e for switching the series-parallel connection of the storage battery, a switch (high-speed circuit breaker for power storage device) 10, switches (contactors) 11 and 12, a charging circuit unit (for 3b and 7b) 13, a charging circuit unit (for 5b) 14, filter reactors 15 and 16, diodes 17 and 18, and a grounding unit 19. Each component will be described later.

The battery-powered drive system of this embodiment can be broadly divided into the following three operation modes.
Table 1 shows operation modes distinguished according to the section and the state of the storage battery.

As shown in Table 1, there are two possible combinations for the vehicle's position ("Section" in Table 1), either an electrified section or a non-electrified section, and three possible combinations for the state of the power storage devices 8a and 8b ("Battery State" in Table 1), either connected in series, connected in parallel, or unused (open state, not connected to the main circuit). Of the six combinations (2 patterns x 3 patterns), the combination of a non-electrified section and a parallel-connected battery state, and the combination of a non-electrified section and an open battery state are omitted as they are unlikely to occur in reality, leaving four patterns.

Here, the vehicle modes are defined as shown in Table 1 above.
The combination of an electrified section and a battery connected in parallel is called "overhead line running mode."
- The combination of non-electrified sections with batteries connected in series is called "battery driving mode."
- The combination of the electrified section and the series connection state of the storage battery is set as "storage battery running mode (emergency)."
This mode is assumed when some kind of problem occurs with the overhead lines or the vehicle, but since the circuit configuration is equivalent to the battery driving mode, it is considered an emergency mode.
- If an abnormality occurs in the power storage devices 8a, 8b, the combination of the electrified section and the open battery state is set to the "DC train mode."
This mode is assumed when an abnormality occurs in the power storage device 8a or 8b.

In addition, in either mode, it must be possible to supply power to the auxiliary load 6. Except in the event of an abnormality, the basic modes are "overhead line running mode" and "battery running mode," but switching between the two modes is performed at electrified stations that have overhead line equipment that can be charged. For example, this could be the end station of an electrified section.

Next, each component of the battery-powered drive system of this embodiment will be described.
The current collector 1 serves to connect the electric rail and the on-board system. Here, the electric rail includes an overhead contact line and a third rail, etc. In this embodiment, an overhead contact line is used as the electric rail.

In a DC electrified section, the current collector 1 is brought into contact with a DC overhead line, and power is supplied to the vehicle system via the vehicle's DC link. This may involve stepping down the voltage from the current collector using a DC/DC converter before connecting to the DC link. On the other hand, in an AC electrified section, the current collector is brought into contact with an AC overhead line, and AC power is converted to DC power via a transformer and a power converter before being connected to the DC link.
In addition, the current collector 1 returns the regenerative energy of the vehicle to the overhead lines when the vehicle is braking.

The current collector 1 is generally a pantograph used for DC or AC overhead lines, and this embodiment also assumes that the current collector 1 is a pantograph. If the current collector 1 is a pantograph, it is folded up and stored in the vehicle in non-electrified sections. However, the current collector is not limited to a pantograph, and also includes devices that collect current from a third rail. In this embodiment, when power is supplied from the overhead line through the current collector 1, the driving of the electric motor 4, the charging and discharging of the storage devices 8a and 8b, and the driving of the auxiliary load 6 are performed through a single DC link, so that fewer devices such as power converters are required compared to when the power from the pantograph is divided into two or more systems. This allows the installation space to be expanded.

The switch (high-speed circuit breaker for the current collector) 2 is installed between the current collector 1 and the DC link, and serves to electrically disconnect the vehicle system from the DC overhead line to prevent adverse effects on the DC overhead line when abnormal power is sent from the DC overhead line or when a problem such as a short circuit occurs in the vehicle's main circuit system. Generally, a switch that can interrupt current quickly and instantaneously is used.

The power conversion unit (inverter) 3a converts DC power from the current collector 1 or the power storage devices 8a and 8b into three-phase AC power based on a command signal from a control unit (not shown) and outputs it to the electric motor 4. In addition, when braking the vehicle, the power conversion unit (inverter) 3a converts the power generated by the electric motor 4 based on a command signal from a control unit (not shown) and outputs it to the DC overhead line or the power storage devices 8a and 8b.

Here, the power conversion unit (inverter) 3a is configured, for example, by a three-phase inverter including switching elements using power semiconductors, and is configured to output, for example, two-level or three-level voltages. The ON/OFF control of the switching elements of the power conversion unit (inverter) 3a is performed, for example, by PWM control or synchronous pulse control. Furthermore, the power conversion unit (inverter) 3a has an upper temperature limit set from the viewpoint of the life span of the elements and peripheral devices, and is protected and controlled to prevent overheating.

The inverter filter capacitor 3b is connected to stabilize the operation of the power conversion unit (inverter) 3a and absorb harmonic components on the DC side, and does not retain a charge when the vehicle power is off, mainly from the perspective of safety. To start the vehicle and operate the power conversion unit (inverter) 3a, the inverter filter capacitor 3b must be charged, for example, by a charging circuit 13. When charging and discharging the inverter filter capacitor 3b, it is desirable not to apply a large current caused by a sudden voltage change, mainly from the perspective of lifespan.

The electric motor 4 generates driving force by controlling the energy supplied from the DC overhead line and the power storage devices 8a and 8b via the current collector 1 in the power conversion unit 3a. The electric motor 4 also operates as a generator when braking the vehicle, converting the kinetic energy and potential energy of the vehicle into electrical energy and outputting it to the power conversion unit 3a. If the voltage driving the electric motor 4 is too high, there is a problem with the insulation voltage, and if the voltage is too low, there are problems with heat generation and reduced efficiency.

The power conversion unit (for auxiliary equipment, SIV) 5a supplies power to auxiliary loads 6, such as the power supply for the control unit (not shown), the air conditioning system in the vehicle, and the interior lights. The power conversion unit (for auxiliary equipment, SIV) 5a generally has a DC link as its input side, and upper and lower voltage limits for stable operation are set. It is also desirable for the power conversion unit (for auxiliary equipment, SIV) 5a to operate at all times, whether the vehicle is running or stopped, to continue to steadily supply power to the auxiliary loads 6. Here, the power conversion unit (for auxiliary equipment, SIV) 5a is composed of, for example, a three-phase inverter including switching elements using power semiconductors.

The SIV filter capacitor 5b is connected to stabilize the operation of the power conversion unit (for auxiliary equipment, SIV) 5a and to absorb harmonic components on the DC side, and is not allowed to retain a charge when the vehicle power is off, mainly from the viewpoint of safety. To start the vehicle and operate the power conversion unit (for auxiliary equipment, SIV) 5a, the SIV filter capacitor 5b must be charged, for example, by a charging circuit 14. When charging and discharging the SIV filter capacitor 5b, it is desirable not to apply a large current caused by a sudden voltage change, mainly from the viewpoint of life span.

The auxiliary loads 6 refer to loads that consume power in parts that are not directly related to the drive system, such as interior lights, air conditioning equipment, and control units. Basically, when the vehicle is in an activated state, the auxiliary loads 6 always require power, so it is desirable for them to be constantly supplied with power from the power conversion unit (for accessories, SIV) 5a. In particular, if the interior lights are turned off during nighttime operation, there is a problem that passenger safety cannot be ensured. One method is to use secondary batteries such as lead-acid batteries or lithium-ion batteries as the power source for the interior lights, but this creates the problem of complicating the design of the vehicle.

When the current collector 1 is connected to the overhead line, the power conversion unit (DC/DC converter) 7a converts the DC power from the overhead line to charge the storage battery. The power conversion unit (DC/DC converter) 7a is, for example, configured as a chopper capable of stepping up and down voltage, with the connection point between the upper arm and the lower arm connected to the output side via a reactor.

The filter capacitor 7b for the DC/DC converter is connected to stabilize the operation of the power conversion unit (DC/DC converter) 7a and to absorb harmonic components on the DC side, and does not retain a charge when the vehicle power is off, mainly from a safety standpoint. To start the vehicle and operate the power conversion unit (DC/DC converter) 7a, the filter capacitor 7b for the DC/DC converter must be charged, for example, by a charging circuit 13. When charging and discharging the filter capacitor 7b for the DC/DC converter, it is desirable not to apply a large current caused by a sudden voltage change, mainly from the standpoint of lifespan.

The power storage devices 8a and 8b serve as the main power source in non-electrified sections, and supply power to the electric motor 4 during power running. When braking, they absorb the regenerative power generated by the electric motor 4 and reuse it for the next power running or to supply power to auxiliary equipment. Here, for example, storage batteries such as lithium-ion batteries, which are rechargeable and dischargeable secondary batteries, are used as the power storage devices 8a and 8b.

To ensure the safety of the power storage devices 8a and 8b and to maximize their performance, it is common for a control board and control device (not shown) dedicated to the power storage devices to be provided. The voltage of a lithium-ion battery varies depending on the charge level, and generally, the higher the charge level, the higher the voltage, and the lower the charge level, the lower the voltage. The voltage change during this period shows different characteristics depending on the type of lithium-ion battery. Furthermore, from the perspective of deterioration and lifespan, upper and lower limits are set for the charge level and voltage that can actually be used with lithium-ion batteries. Similarly, from the perspective of deterioration, maximum charge and discharge currents are set. For this reason, it is necessary to design the battery taking these factors into consideration.

In FIG. 1, only the power storage devices 8a and 8b are shown, but 8a and 8b may be composed of smaller units such as storage battery modules that make them up. Also, in FIG. 1, only one parallel storage device is shown, but there may be multiple power storage devices that are similarly configured to be switchable between series and parallel and are connected in parallel to the power storage devices 8a and 8b.

The storage batteries 8a and 8b are connected in different ways in electrified and non-electrified sections. In electrified sections, the storage batteries 8a and 8b are basically connected in parallel. In Japan, the overhead line voltage in DC electrified sections is approximately 1500V, but in reality the overhead line voltage varies between 1000 and 1800V depending on the relative positions of the substation and the load. In non-electrified sections, the storage batteries 8a and 8b are basically connected in series. Here, if the storage battery voltage when the storage batteries 8a and 8b are connected in series is designed to be equivalent to the overhead line voltage, there is a great advantage in circuit operation.

For example, if the battery voltage when the storage devices 8a and 8b are connected in series is designed to be approximately 1500V, it will be possible to drive the motor 4 and auxiliary load 6 at the same voltage level in both electrified and non-electrified sections. This also means that in the electrified section, when the storage devices 8a and 8b are connected in parallel, the battery voltage will be approximately 750V, and even if the overhead line voltage fluctuates in the range of 1000 to 1800V, the power conversion unit (DC/DC converter) 7a only needs to perform step-down operation, which is expected to simplify the hardware structure and control. Here, the overhead line voltage being 1500V class is just one example, and the principles used in this embodiment will hold for voltages higher or lower.

The switches (contactors) 9a, 9b, 9c, 9d, and 9e are used to switch the series-parallel connection of the storage batteries. In practice, the series-parallel switching of the storage devices 8a and 8b is performed when no current is flowing, so the interrupting capability of the switches 9a to 9e may be low. When the storage batteries are connected in parallel, the switches 9a, 9b, 9d, and 9e are on (closed), and the switch 9c is off (open). On the other hand, when the storage batteries are connected in series, the switches 9a, 9c, and 9e are on (closed), and the switches 9b and 9d are off (open). In addition, in order to prevent a short circuit caused by a direct connection between the high-potential side and the low-potential side of the storage devices 8a and 8b, when the switches 9a, 9c, and 9e are on (closed), one or more of the switches 9d and 9e must not be on (closed).

The switch (high-speed circuit breaker for the power storage device) 10 electrically disconnects the power storage devices 8a and 8b from the vehicle system to prevent mutual adverse effects in the event of an abnormality in the power storage devices 8a and 8b or a problem such as a short circuit in the vehicle's main circuit system. Generally, a switch capable of interrupting current quickly and instantly is used. It also turns off (opens) when switching between series and parallel storage batteries, electrically disconnecting the power storage devices 8a and 8b from the main circuit system.

In battery running mode, switch (contactor) 11 serves to connect the power storage devices 8a and 8b to the drive system consisting of the power conversion unit (inverter) 3a and the electric motor 4. The existence of a path formed when switch (contactor) 11 is on (closed) enables power running using the power of the power storage devices 8a and 8b and regenerative operation to the power storage devices 8a and 8b without being blocked by diodes 17 and 18, which will be described later. In overhead line running mode, it must be always off (open). This is to prevent the generation of large currents due to the direct connection of two different DC power sources, the overhead line and the power storage devices 8a and 8b, and the resulting equipment failures and accidents.

In the overhead line running mode, the switch (contactor) 12 is turned on (closed) and connects the output of the power conversion unit (DC/DC converter) 7a to the high potential side of the power storage devices 8a and 8b to generate a current path during charging operation. In the battery running mode, the power conversion unit (DC/DC converter) 7 is not operating, so the switch (contactor) 12 is turned off (open).

The charging circuit unit (for 3b and 7b) 13 is composed of a parallel circuit of a resistor and a switch (a switching element such as a contactor or semiconductor), and is responsible for charging the filter capacitor 3b for the inverter and the filter capacitor 7b for the DC/DC converter. To operate the power conversion unit (inverter) 3a and the power conversion unit (DC/DC converter) 7a, it is necessary to charge the filter capacitors 3b and 7b to a voltage equivalent to that of the DC power source from the overhead line or storage battery. However, there is no charge when the vehicle power is off.

The procedure for charging the filter capacitors 3b and 7b is as follows. First, the charging circuit unit (for 3b and 7b) 13 charges the filter capacitors to a certain voltage while suppressing the charging current through a path that goes through a resistor. Then, a switch (a switching element such as a contactor or semiconductor) is used to switch to a path that does not go through a resistor. Finally, the power conversion unit (inverter) 3a and the power conversion unit (DC/DC converter) 7a are operated through a path that does not have a resistor and only has a switch (a switching element such as a contactor or semiconductor). This series of operation modes takes into consideration resistance loss and heat generation. The charging circuit unit (for 3b and 7b) 13 shown in FIG. 1 has a simple configuration, but the above-mentioned functions may be realized using multiple resistors and switches (switching elements such as contactors or semiconductors).

The charging circuit unit (for 5b) 14 is composed of a parallel circuit of a resistor and a switch (a switching element such as a contactor or semiconductor), and is responsible for charging the filter capacitor 5b for the SIV. To operate the power conversion unit (for auxiliary equipment, SIV) 5a, it is necessary to charge the filter capacitor 5b to a voltage equivalent to that of the DC power supply from the overhead line or storage battery. However, there is no charge when the vehicle power supply is turned off.

When the power supply to the power conversion unit (for auxiliary equipment, SIV) 5a is switched between the overhead line voltage and the power storage devices 8a and 8b, it is necessary to adjust the voltage of the filter capacitor 5b using the charging circuit unit (for 5b) 14 in order to enable continuous operation of the auxiliary equipment. Here, in order to adjust the voltage of the filter capacitor 5b, for example, first, the charging current is suppressed by a path via a resistor while charging to a certain voltage, and then the path is switched to one that does not pass through a resistor by a switch (a contactor or a switching element such as a semiconductor). Other means include a method of charging the filter capacitor 5b by turning on and off a switching element such as a semiconductor to adjust the conduction rate. In any case, when the filter capacitor 5b is adjusted to the power supply voltage without any problems and the power conversion unit (for auxiliary equipment, SIV) 5a is operating steadily, the path is switched to one that does not pass through a resistor, taking into account resistance loss and heat generation.

The filter reactor 15 acts as a low-pass filter to prevent harmonics caused by switching in the power conversion unit (inverter) 3a and power conversion unit (DC/DC converter) 7a from leaking out to the power supply. This is a configuration that is commonly used in railway vehicles. In addition, in the event of a short circuit occurring in the power conversion unit (inverter) 3a or power conversion unit (DC/DC converter) 7a, it is common to select one with a large inductance to reduce the current change per unit time.

The filter reactor 16 acts as a low-pass filter to prevent harmonics caused by switching in the power conversion unit (for auxiliary equipment, SIV) 5a from flowing out to the power supply. It also has the function of reducing the current change per unit time in the event of a short circuit in the power conversion unit (for auxiliary equipment, SIV) 5a.

The diode 17 plays a role of smoothing the power on the input side of the power conversion unit (for accessories, SIV) 5a when the power source of the power conversion unit (for accessories, SIV) 5a is an overhead line.
Diode 18 plays a role in smoothing the power on the input side of power conversion unit (for accessories, SIV) 5a when the power source of power conversion unit (for accessories, SIV) 5a is the power storage devices 8a and 8b.

The cathodes of diodes 17 and 18 are connected at connection point 20. By matching diodes 17 and 18, one of the diodes turns on depending on the magnitude relationship between the overhead line voltage and the voltages of the storage devices 8a and 8b, making it possible to supply power to the power conversion unit (for auxiliary equipment, SIV) 5a. Even if there is a voltage difference between the overhead line voltage and the voltages of the storage devices 8a and 8b, no current will flow between the power sources due to the blocking of the diodes that are off.

In a railway vehicle, the ground contact part 19 corresponds to the wheels that come into contact with the metal rails. However, this is not the case if the wheels of the railway vehicle are rubber tires, etc., and the ground contact part 19 may be the body earth.

FIG. 2 is a diagram showing the circuit configuration of the battery-powered drive system in the overhead line running mode.
In the overhead line running mode, the power source for devices such as the motor 4 and the auxiliary load 6 is the overhead line. The power storage devices 8a and 8b are connected in parallel with each other. The power storage devices 8a and 8b are charged by a power conversion unit (DC/DC converter) 7a. For example, constant current charging, constant voltage charging, or CCCV charging, which is a combination of these, may be used. Charging is possible even while traveling in an electrified section. The total voltage of the parallel-connected storage batteries is generally lower than the overhead line voltage, so diode 17 is on (conducting) and diode 18 is off (blocking).

FIG. 3 is a diagram showing the circuit configuration of the battery-powered drive system in the battery driving mode.
In the battery running mode, the power sources for devices such as the motor 4 and the auxiliary load 6 are the power storage devices 8a and 8b. The power storage devices 8a and 8b are connected in series. The power storage devices 8a and 8b are charged by regenerative operation during braking. However, in flat sections, the amount of power that can be reused through regenerative operation generally does not exceed the power consumed during power running, so the charging rate tends to decrease as the train travels through non-electrified sections. It is important to manage the amount of charge until the train arrives at the next station where charging is possible.

Figure 4 shows an example of a flowchart for switching the battery configuration of the battery-powered drive system from parallel connection to series connection (overhead line driving mode → battery driving mode). Note that in Figures 4 and 5, the overhead line driving mode is indicated as "mode A" and the battery driving mode is indicated as "mode B."

At the charging station, when charging to the storage battery is completed in the overhead line running mode, a command to switch the mode to the storage battery running mode is issued, which is step 101 (S101). This command to switch modes may be issued by an operator using a switch, or may be issued automatically by the vehicle when the end of charging is detected.

Furthermore, under normal circumstances, the mode is switched from the overhead line running mode to the battery running mode while the train is stopped at a station.
Here, the power storage devices 8a and 8b are connected in parallel to each other, and the voltages of the respective devices are substantially equal.

In the state of step 101 (S101), power is supplied to the auxiliary load 6 from the power supplied through the overhead line.
Since power is being continuously supplied to the auxiliary load 6, the charging circuit unit (for 5b) 14 is in a conductive state without passing through a resistor.

In step 102 (S102), the power conversion unit (inverter) 3a and the power conversion unit (DC/DC converter) 7a do not operate during mode switching, so the operation of each power conversion unit is stopped.

In step 103 (S103), the stopped power conversion unit (inverter) 3a and the charging circuit unit (for 3b and 7b) 13 of the power conversion unit (DC/DC converter) 7a are disconnected to an open state. Disconnection here means that the overhead line side and the input sides of the power conversion unit (inverter) 3a and the power conversion unit (DC/DC converter) 7a are not electrically connected. This disconnection of the charging circuit unit (for 3b and 7b) 13 is not essential, but is preferable to prevent a large current from flowing into the filter capacitors 3b and 7b when a large current is generated due to a voltage difference when performing step 108 (S108) described later.

In step 104 (S104), switch (contactor) 12 and switch (high-speed circuit breaker for power storage device) 10 are turned off (open). Either of these off (open) operations can be performed first. With switch (high-speed circuit breaker for power storage device) 10 turned off (open), power storage devices 8a and 8b are disconnected from the main circuit system, and the series-parallel configuration can be rearranged.

In step 105 (S105), switches (contactors) 9b and 9d are turned off (open). Either switch can be turned off (opened) first, but it is recommended that switch 9b on the higher potential side be turned off (opened) first to prevent the potentials of the storage devices 8a and 8b from floating.

In step 106 (S106), switch (contactor) 9c is turned on (closed). This turns on (closes) the power storage devices 8a and 8b so that the total battery voltage is twice as high as in overhead line running mode. This completes the switch to a series connection of multiple batteries. In this step 106 (S106), the series-parallel configuration of the multiple batteries is merely changed, and power to the auxiliary load 6 is still supplied from the overhead line.

In step 107 (S107), switch (high-speed circuit breaker for storage device) 10 is turned on (closed). When this on (closed) operation is performed, the overhead line and the storage devices 8a and 8b connected in series are connected via diodes 17 and 18, whose cathodes are butted together. The diodes that are turned on (conducting) are determined according to the magnitude relationship between the overhead line voltage (referred to as "Vf") and the total battery voltage of the storage devices 8a and 8b connected in series (referred to as "Vbats" (=Voltage BATtery Series connection)). Step 108 (S108) shows the branching of this physical phenomenon.

In step 108 (S108), if the overhead line voltage Vf is greater than the total battery voltage Vbats of the series-connected storage devices 8a and 8b (Yes), diode 17 is turned on (conducting) and diode 18 is turned off (blocking). In this case, power to the auxiliary load 6 is still supplied from the overhead line.

As for the SIV filter capacitor 5b, since it is already operated by the overhead line voltage, no voltage difference occurs even by step 108 (S108), so the charging circuit unit (for 5b) 14 does not need to perform any special operation and can simply maintain the conductive state. This is shown in step 109 (S109).

Because the mode is switched to battery-powered running mode, once step 109 (S109) is completed, the overhead lines and the main circuit system must be electrically disconnected. This is carried out in step 111 (S111). In step 111 (S111), switch (high-speed circuit breaker for current collector) 2 is turned off (open) and the pantograph, which is the current collector 1, is stored. The order of these two steps does not matter, but it is generally better to turn switch (high-speed circuit breaker for current collector) 2 off (open) first.

After step 111 (S111) is completed, the power supply path from the overhead line is cut off, so diode 17 is turned off (blocked). Also, since the voltage of filter capacitor 5b for the SIV is equivalent to the overhead line voltage, diode 18 remains off (blocked) due to the condition Vf>Vbats.

While both diodes 17 and 18 are off (blocked), there is no power source connected to the power conversion unit (for auxiliary equipment, SIV) 5a. However, the power conversion unit (for auxiliary equipment, SIV) 5a supplies power to the auxiliary load 6 using the charge stored in the SIV filter capacitor 5b. This operating mode continues for a period ranging from less than one second to several seconds, depending on the relationship between the capacitance of the SIV filter capacitor 5b and the power consumption of the auxiliary load 6.

As the SIV filter capacitor 5b discharges, the voltage drops, and eventually the voltage on the anode side of the diode 18 falls below Vbats. This causes the diode 18 to turn on (conduct), and the power source for the auxiliary load 6 switches to the power storage devices 8a and 8b.

Next, the other condition in the branch at step 108 (S108) will be described.
In step 108 (S108), if the total battery voltage Vbats of the series-connected power storage devices 8a and 8b is greater than the overhead line voltage Vf (No), the diode 18 is turned on (conducting) and the diode 17 is turned off (blocking). Until immediately before performing step 107 (S107), power was being supplied to the auxiliary load 6 from the overhead line, but since the diode 17 is turned off (blocking), power must be supplied from the power storage devices 8a and 8b. Since the voltage of the SIV filter capacitor 5b is equivalent to the overhead line voltage, the diode 18 is turned on (conducting) due to the condition of Vbats>Vf, and it is possible to immediately switch to power supply from the power storage devices 8a and 8b.

Under these conditions, it is assumed that a large current will flow into the SIV filter capacitor 5b depending on the voltage difference between Vbats and Vf. In this case, the charging circuit unit (for 5b) 14 can be switched to limit the current, for example, and the SIV filter capacitor 5b can be charged with an appropriate charging current up to the total battery voltage Vbats of the series-connected storage devices 8a and 8b. Step 110 (S110) corresponds to this operating mode.

When step 110 (S110) is executed, the power conversion unit (for auxiliary machinery, SIV) 5a is not receiving power from the overhead line, so in step 111 (S111), the switch (high-speed circuit breaker for the current collector) 2 is turned off (opened) and no problem occurs even if the pantograph, which is the current collector 1, is stored.

The above is an explanation of the operating modes in both cases regarding the branching of step 108 (S108). In either branching condition, the power source of the auxiliary load 6 is switched to the power storage devices 8a and 8b, and there is no further branching of the state, so the remaining steps will be explained together.

It should be noted here that the branch at step 108 (S108) is a branch based on the physical circuit state. In general, charging the voltage of the filter capacitor 5b for the SIV is often performed by the control unit of the power conversion unit (for accessories, SIV) 5a (not shown) controlling the charging circuit unit (for 5b) 14. Therefore, there is no need to compare the magnitude of the voltages in the actual switching program and switch the sequence control depending on the comparison result. Therefore, at least one type of sequence control for the pattern of switching from the overhead line running mode to the battery running mode is sufficient.

In step 112 (S112), switch (contactor) 11 is turned on (closed). This operation turns on (conducts) either diode 17 or diode 18. However, the power source for auxiliary load 6 remains the storage devices 8a and 8b. Which diode actually turns on (conducts) is determined by factors such as the magnitude of the resistance of the elements and wiring in the path.

By turning on (closing) switch (contactor) 11 in step 112 (S112), a path is formed from power storage devices 8a and 8b to power conversion unit (inverter) 3a and charging circuit unit (for 3b and 7b) 13 of power conversion unit (DC/DC converter) 7a without passing through diodes 17 and 18.

In step 113 (S113), the power conversion unit (inverter) 3a and the charging circuit unit (for 3b and 7b) 13 of the power conversion unit (DC/DC converter) 7a are operated to charge and discharge the filter capacitors 3b and 7b, which have been charged to the overhead line voltage Vf, to the total battery voltage Vbats of the series-connected storage devices 8a and 8b. When the voltage adjustment by charging and discharging the filter capacitors 3b and 7b is completed, the charging circuit unit (for 3b and 7b) 13 may be short-circuited.

After the above steps are performed, the mode change to the battery driving mode is completed in step 114 (S114). The power storage devices 8a and 8b are now connected in series with each other, and power supply to the auxiliary load 6 can be continued without interruption during the mode change.

FIG. 5 is a diagram showing an example of a flowchart when the battery configuration of the battery-powered drive system is switched from a series connection to a parallel connection (from a battery running mode to an overhead line running mode).
When the vehicle has finished traveling in the non-electrified section in the battery traveling mode and has arrived at the charging station, the mode is switched to the overhead line traveling mode in order to charge the battery from the overhead line and travel in the electrified section. Step 201 (S201) refers to a state in which the vehicle has stopped and a command to switch the mode to the overhead line traveling mode has been issued. This command to switch the mode may be issued by an operator using a switch or may be issued automatically by the vehicle side upon detection of a stop in the electrified section and the charging rate of the battery.

Furthermore, under normal circumstances, the switching from the battery running mode to the overhead line running mode is performed while the vehicle is stopped at a station.
The power storage devices 8a and 8b are connected in series to each other, and the voltages and capacities of the power storage devices 8a and 8b are equal to each other.

In step 201 (S201), the auxiliary load 6 is supplied with electric power from the power storage devices 8a and 8b.
Since power is being steadily supplied to the auxiliary load 6, the charging circuit section (for 5b) 14 is in a conductive state without passing through a resistor.

In step 202 (S202), the power conversion unit (inverter) 3a does not operate during mode switching, so the operation of the power conversion unit (inverter) 3a is stopped.

In step 203 (S203), the stopped power conversion unit (inverter) 3a and the charging circuit unit (for 3b and 7b) 13 of the power conversion unit (DC/DC converter) 7a are disconnected to an open state. Disconnection here means that the overhead line side and the input sides of the power conversion unit (inverter) 3a and the power conversion unit (DC/DC converter) 7a are not electrically connected. This disconnection of the charging circuit unit (for 3b and 7b) 13 is not essential, but is preferable to prevent a large current from flowing into the filter capacitors 3b and 7b when a large current is generated due to a voltage difference when performing step 205 (S205) described later.

In step 204 (S204), the switch (contactor) 11 is turned off (open). This causes the power storage devices 8a and 8b to be used as a power source and supply power to the auxiliary load 6 via the diode 18. By keeping the switch (contactor) 11 turned off (open) in this step 204 (S204), the overhead line and the power storage devices 8a and 8b are prevented from being directly connected when step 205 (S205) described below is performed to connect the overhead line to the main circuit system.

In step 205 (S205), the pantograph, which is the current collector 1, is brought into contact with the overhead line, and the switch (high-speed circuit breaker for the current collector) 2 is turned on. When this operation is performed, the power storage devices 8a and 8b, which are connected in series with the overhead line, are connected via diodes 17 and 18, which have their cathodes butted together. The diodes that are turned on (conducting) are determined based on the magnitude relationship between the overhead line voltage Vf and the total battery voltage Vbats of the series-connected power storage devices 8a and 8b. Step 206 (S206) shows the branching of this physical phenomenon.

In step 206 (S206), if the overhead line voltage Vf is greater than the total battery voltage Vbats connected in series (Yes), diode 17 is turned on (conducting) and diode 18 is turned off (blocking). Until just before step 206 (S206) was executed, power was being supplied to auxiliary load 6 from power storage devices 8a and 8b, but now that diode 18 is turned off (blocking), power must be supplied from the overhead line. Since the voltage of filter capacitor 5b for the SIV is equivalent to the total battery voltage of power storage devices 8a and 8b connected in series, diode 17 is turned on (conducting) due to the condition Vf>Vbats, and it is possible to immediately switch to power supply from the overhead line.

Note that under this condition of Vf>Vbats, a large current may flow into the SIV filter capacitor 5b depending on the voltage difference between Vf and Vbats. To deal with this situation, the charging circuit unit (for 5b) 14 can be switched to limit the current, for example, and the SIV filter capacitor 5b can be charged to the overhead line voltage Vf with an appropriate charging current. This is shown in step 207 (S207).

When step 207 (S207) is executed, the power conversion unit (for auxiliary machinery, SIV) 5a switches to power supply from the overhead line, so there is no problem even if the power storage devices 8a and 8b are disconnected from the system by turning off (opening) the switch (high-speed circuit breaker for the power storage device) 10 in step 209 (S209).

Next, the other condition in the branch at step 206 (S206) will be described.
In step 206 (S206), if the total battery voltage Vbats of the series-connected power storage devices 8a and 8b is greater than the overhead line voltage Vf (No), the diode 18 is turned on (conducting) and the diode 17 is turned off (blocking). In this case, the power to the auxiliary load 6 is still supplied from the power storage devices 8a and 8b.

The filter capacitor 5b for the SIV is already operated by the total battery voltage Vbats of the storage devices 8a and 8b connected in series, so in this case no voltage difference occurs, and the charging circuit unit (for 5b) 14 does not need to operate differently and can simply remain conductive. This is shown in step 208 (S208).

In order to switch the series/parallel connection of the power storage devices 8a and 8b, it is necessary to electrically disconnect the power storage devices 8a and 8b from the main circuit system after step 208 (S208) is executed. This operation mode is executed in step 209 (S209). In step 209 (S209), the switch (high-speed circuit breaker for the power storage device) 10 is turned off (opened).

After step 208 (S208) is executed, the power supply path from the power storage devices 8a and 8b is cut off, and the diode 18 is turned off (blocked). Also, since the voltage of the SIV filter capacitor 5b is equivalent to the total battery voltage Vbats of the series-connected power storage devices 8a and 8b, the condition Vbats>Vf is satisfied, and therefore the diode 17 also remains in the off (blocked) state.

While both diodes 17 and 18 are off (blocked), there is no power source connected to the power conversion unit (for auxiliary equipment, SIV) 5a. However, the power conversion unit (for auxiliary equipment, SIV) 5a supplies power to the auxiliary load 6 using the charge stored in the SIV filter capacitor 5b. This operating mode continues for a period ranging from less than one second to several seconds, depending on the relationship between the capacitance of the SIV filter capacitor 5b and the power consumption of the auxiliary load 6. As the SIV filter capacitor 5b discharges, the voltage drops, and eventually the voltage on the anode side of diode 17 becomes equal to or lower than Vf, causing diode 17 to turn on (conduct), and the power source for the auxiliary load 6 switches to the overhead line.

The above is an explanation of the operating modes in both cases regarding the branching of step 206 (S206). In either case, the power source of the auxiliary load 6 is switched to the overhead line, and there is no further branching of the state, so the remaining steps will be explained together.

It should be noted here that the branch at step 206 (S206) is a branch based on the physical circuit state. In general, charging the voltage of the filter capacitor 5b for the SIV is often performed by the control unit of the power conversion unit (for accessories, SIV) 5a (not shown) controlling the charging circuit unit (for 5b) 14. Therefore, there is no need to compare the magnitude of the voltages in the actual switching program and switch the sequence control depending on the comparison result. Therefore, at least one type of sequence control for the pattern of switching from the battery driving mode to the overhead line driving mode is sufficient.

In step 209 (S209), the switch (high-speed circuit breaker for the energy storage device) 10 is turned off (open), disconnecting the energy storage devices 8a and 8b from the main circuit system and enabling the series-parallel configuration to be rearranged.

In step 210 (S210), switch (contactor) 9c is turned off (open).

In step 211 (S211), the switches (contactors) 9b and 9d are turned on (closed). Either of these on (close) operations can be performed first, but it is recommended to turn on (close) the switch 9d on the lower potential side first in order to prevent the potentials of the storage batteries 8a and 8b from floating. However, in order to prevent a short circuit between the storage batteries, step 211 (S211) must be performed after step 210 (S210).
After step 211 (S211), the power storage devices 8a and 8b are connected in parallel to each other. Also, power is supplied to the auxiliary load 6 from the overhead line.

In step 212 (S212), switch (high-speed circuit breaker for storage device) 10 is turned on (closed). At this time, since storage devices 8a and 8b are connected in parallel, the voltage generally does not exceed the overhead line voltage, and diode 17 is on (conducting) and diode 18 is off (blocking).

In step 213 (S213), the charging circuit unit (for 3b and 7b) 13 is operated to charge and discharge the filter capacitors 3b and 7b, which have been charged to a voltage equivalent to the total battery voltage Vbats of the series-connected storage devices 8a and 8b, to a voltage equivalent to the overhead line voltage Vf. When the voltage adjustment by charging and discharging the filter capacitors 3b and 7b is completed, the charging circuit unit (for 3b and 7b) 13 can be short-circuited.

In step 214 (S214), the switch (contactor) 12 is turned on (closed). This on (closed) state connects the output of the power conversion unit (DC/DC converter) 7a to the parallel-connected power storage devices 8a and 8b, enabling charging.

After the above steps are performed, in step 215 (S215), the mode switching to the overhead line running mode is completed. The power storage devices 8a and 8b are now connected in parallel with each other, and it is possible to continue supplying power to the auxiliary load 6 during the mode switching without interruption.

As described above, we have explained the basic overhead line running mode and battery running mode under normal circumstances, as well as the operating conditions when switching between the two modes and the fact that power can be continuously supplied to the auxiliary load 6 even in that case.

FIG. 6 is a diagram showing the circuit configuration of a battery-powered drive system in a DC train mode.
Since the switch (high-speed circuit breaker for the power storage device) 10 and the switch (contactor) 12 are off (open), the power storage devices 8a and 8b are not connected to the main circuit system. This DC train mode is assumed to occur when the protection operation of the power storage devices 8a and 8b is activated by a control unit (not shown) while the vehicle is traveling mainly in an electrified section. The circuit configuration in this DC train mode is equivalent to the circuit configuration of a railway vehicle traveling in a normal DC section.

Furthermore, according to the above embodiment, at least the following technical matters are included.
<Technical item 1>
In a traction system for a railway vehicle equipped with a storage battery device, the storage battery device has a plurality of storage batteries and a switching unit that switches between a series connection and a parallel connection of the plurality of storage batteries, and includes a first circuit breaker that cuts off power supplied from an electric rail line to a DC link in the railway vehicle, a first power conversion unit that converts power input from the DC link into power for driving an electric motor, a second power conversion unit that converts power input from the DC link into power for charging the storage battery device, and a power converter that converts power input from the DC link into power for charging the storage battery device. The power converter includes a third power conversion unit that converts power input from the storage battery device into power to drive auxiliary equipment, a filter capacitor connected to the input side of the third power conversion unit, a second circuit breaker that cuts off power supplied from the storage battery device to the DC link, a first rectification unit that passes power from the DC link to the third power conversion unit, and a second rectification unit that passes power from the storage battery device to the third power conversion unit, and output points on the third power conversion unit side of the first rectification unit and the second rectification unit are connected to the positive electrode side of the filter capacitor.

<Technical item 2>
In the traction system for railway vehicles described in Technical Item 1 above, when switching between power supply from the electric rail and power supply from the storage battery device, the multiple storage batteries are switched from a parallel connection to a series connection or from a series connection to a parallel connection, and the first rectification unit or the second rectification unit is rendered conductive depending on the magnitude relationship between the voltage of the electric rail and the voltage of the storage battery device connected in series, thereby continuing the power supply to the auxiliary equipment without interruption.

<Technical item 3>
In the railway vehicle drive system described in Technical Item 1 or Technical Item 2 above, a charging circuit is provided between the output points on the third power conversion unit side of the first rectification unit and the second rectification unit and the positive electrode side of the filter capacitor, and the voltage of the filter capacitor is adjusted.

<Technical item 4>
In the traction system for railway vehicles described in Technical Item 3 above, the charging circuit is a parallel circuit of a semiconductor switch and a resistor.

<Technical item 5>
In the railway vehicle traction system described in Technical Item 4 above, when there is a potential difference between the voltage of the electric rail or the voltage of the series-connected storage battery device and the voltage of the filter capacitor, the semiconductor switch is turned on and off to limit the charging current to the filter capacitor.

<Technical item 6>
A railway vehicle equipped with a railway vehicle drive system according to any one of Technical Item 1 to Technical Item 5 above.

<Technical item 7>
In a method for driving a railway vehicle, the railway vehicle is driven by power supplied from an electric power line to a DC link in the railway vehicle or by power supplied from a plurality of storage batteries mounted on the railway vehicle. The railway vehicle is equipped with a power converter that converts power input from the DC link or the plurality of storage batteries into power for driving auxiliary machinery. When the railway vehicle is switched from a mode in which it is driven by power from the electric power line to a mode in which it is driven by power from the plurality of storage batteries, the method disconnects the plurality of storage batteries from the DC link, switches the plurality of storage batteries connected in parallel to a series connection, and converts the plurality of storage batteries into a series connection. a sequence is executed in which the multiple storage batteries connected in series are connected to a DC link, and when the voltage of the electric power line is greater than the voltage of the multiple storage batteries connected in series, the first rectifier prevents power input from the DC link from passing in the direction of the multiple storage batteries, and the second rectifier passes the power in the direction of the power converter, and when the voltage of the multiple storage batteries connected in series is greater than the voltage of the electric power line, the second rectifier prevents power input from the multiple storage batteries from passing in the direction of the electric power line, and the first rectifier passes the power in the direction of the power converter, thereby disconnecting the DC link from the electric power line.

<Technical item 8>
In the railway vehicle drive method described in Technical item 7 above, when the railway vehicle switches from a mode in which it is driven by power from multiple storage batteries to a mode in which it is driven by power from the electric rail, the multiple storage batteries connected in series are disconnected from the DC link and the DC link is connected to the electric rail; if the voltage of the electric rail is higher than the voltage of the multiple storage batteries connected in series, the first rectifier prevents power input from the DC link from passing in the direction of the multiple storage batteries, and the second rectifier passes it in the direction of the power converter; if the voltage of the multiple storage batteries connected in series is higher than the voltage of the electric rail, the second rectifier prevents power input from the multiple storage batteries from passing in the direction of the electric rail, but passes it in the direction of the power converter by the first rectifier; and when power input from the DC link is supplied to the power converter, a sequence is executed to switch the multiple storage batteries connected in series to a parallel connection.

<Technical Issue 9>
In a method for driving a railway vehicle, the railway vehicle is driven by power supplied from an electric power line to a DC link in the railway vehicle or by power supplied from a plurality of storage batteries mounted on the railway vehicle. The railway vehicle is equipped with a power converter that converts power input from the DC link or the plurality of storage batteries into power for driving auxiliary equipment. When the railway vehicle switches from a mode in which the railway vehicle is driven by power from the plurality of storage batteries to a mode in which the railway vehicle is driven by power from the electric power line, the plurality of storage batteries connected in series are disconnected from the DC link, the DC link is connected to the electric power line, and the plurality of storage batteries connected in series are converted into power for driving auxiliary equipment. When the voltage of the electric power line is greater than the voltage of the electric power line, the first rectifier does not pass the power input from the DC link in the direction of the multiple storage batteries, but passes it in the direction of the power converter by the second rectifier; when the voltage of the multiple storage batteries connected in series is greater than the voltage of the electric power line, the second rectifier does not pass the power input from the multiple storage batteries in the direction of the electric power line, but passes it in the direction of the power converter by the first rectifier; and when the power input from the DC link is supplied to the power converter, a sequence is executed to switch the multiple storage batteries connected in series to a parallel connection.

<Technical item 10>
In the driving method for a railway vehicle described in any one of Technical Items 7 to 9 above, the railway vehicle includes a filter capacitor provided on the input side of the power converter, and a charging circuit provided between the DC link and the filter capacitor, and when power from the electric rail or the multiple storage batteries is input to the power converter, the voltage of the filter capacitor is adjusted by the charging circuit.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

1...current collector, 2...switch (high-speed circuit breaker for current collector),
3a...power conversion unit (inverter), 3b...filter capacitor for inverter,
4...motor, 5a...power conversion unit (for auxiliary machinery, SIV),
5b...filter capacitor for SIV, 6...auxiliary load,
7a...power conversion unit (DC/DC converter),
7b...filter capacitor for DC/DC converter, 8a, 8b...electric storage device,
9a, 9b, 9c, 9d, 9e...switches (contactors),
10...switch (high-speed circuit breaker for power storage device), 11, 12...switch (contactor),
13: charging circuit section (for 3b and 7b), 14: charging circuit section (for 5b),
15, 16 ... filter reactor, 17, 18 ... diode, 19 ... ground portion,
20...Connection point

Claims (10)

In a drive system for a railway vehicle equipped with a storage battery device,
the storage battery device includes a plurality of storage batteries and a switching unit that switches between a series connection and a parallel connection of the plurality of storage batteries;
a first circuit breaker that cuts off power supplied from the electric rail to a DC link in the rail car;
a first power conversion unit that converts the power input from the DC link into power for driving an electric motor;
a second power conversion unit that converts the power input from the DC link into power for charging the storage battery equipment;
a third power conversion unit that converts the power input from the DC link or the storage battery device into power for driving an auxiliary device;
A filter capacitor connected to an input side of the third power conversion unit;
a second breaker that cuts off power supplied from the storage battery equipment to the DC link;
a first rectification unit that passes electric power from the DC link to the third power conversion unit;
a second rectification unit that passes electric power from the storage battery device to the third power conversion unit;
Equipped with
a first rectifier unit and a second rectifier unit each having an output terminal on a side of the third power converter unit that is connected to a positive electrode side of the filter capacitor; 2. The drive system for a rail vehicle according to claim 1,
When switching between the power supply from the electric power line and the power supply from the storage battery device,
A traction system for railway vehicles, characterized in that the multiple storage batteries are switched from a parallel connection to a series connection or from a series connection to a parallel connection, and the first rectification unit or the second rectification unit is brought into conduction depending on the magnitude relationship between the voltage of the electric rail and the voltage of the storage battery device connected in series, thereby continuing the power supply to the auxiliary equipment without interruption. 3. A drive system for a railway vehicle according to claim 1,
a charging circuit provided between said output point and a positive electrode of said filter capacitor, said charging circuit adjusting a voltage of said filter capacitor; 4. A drive system for a railway vehicle according to claim 3,
13. A traction system for a railway vehicle, wherein the charging circuit is a parallel circuit of a semiconductor switch and a resistor. 5. A drive system for a railway vehicle according to claim 4,
A traction system for railway vehicles, characterized in that when there is a voltage difference between the voltage of the electric rail or the voltage of the series-connected storage battery device and the voltage of the filter capacitor, the semiconductor switch is operated on and off to limit the charging current to the filter capacitor. A railway vehicle equipped with the railway vehicle drive system according to claim 1 or 2. A method for driving a railway vehicle using power supplied from an electric power line to a DC link in the railway vehicle or power supplied from a plurality of storage batteries mounted on the railway vehicle, comprising:
the railway vehicle includes a power converter that converts power input from the DC link or the plurality of storage batteries into power for driving an auxiliary machine;
When the railway vehicle switches from a mode driven by electric power from the electric rail to a mode driven by electric power from the plurality of storage batteries,
disconnecting the plurality of batteries from the DC link;
Switching the parallel-connected storage batteries to a series connection;
connecting the plurality of series-connected batteries to the DC link;
when a voltage of the electric power line is greater than a voltage of the plurality of storage batteries connected in series, a first rectifier is used to prevent the power input from being passed in a direction toward the plurality of storage batteries, and a second rectifier is used to pass the power input from the DC link in a direction toward the power converter;
when a voltage of the plurality of storage batteries connected in series is greater than a voltage of the electric rail, the second rectifier does not pass power input from the plurality of storage batteries in a direction toward the electric rail, but passes the power in a direction toward the power converter by the first rectifier;
2. A traction method for a railway vehicle, comprising: executing a sequence for disconnecting said DC link from said electric rail. 8. A method for driving a railway vehicle according to claim 7,
When the railcar is switched from a mode driven by power from the plurality of storage batteries to a mode driven by power from the electric rail,
disconnecting the plurality of series-connected storage batteries from the DC link;
connecting the DC link to the electric rail;
when a voltage of the electric power line is higher than a voltage of the plurality of storage batteries connected in series, the first rectifier does not pass power input from the DC link in a direction toward the plurality of storage batteries, but passes the power in a direction toward the power converter by the second rectifier;
when a voltage of the plurality of storage batteries connected in series is greater than a voltage of the electric rail, the second rectifier does not pass power input from the plurality of storage batteries in a direction toward the electric rail, but passes the power in a direction toward the power converter by the first rectifier;
a driving method for a railway vehicle, comprising: a sequence for switching the series-connected storage batteries to a parallel connection when power input from the DC link is supplied to the power converter; A method for driving a railway vehicle using power supplied from an electric power line to a DC link in the railway vehicle or power supplied from a plurality of storage batteries mounted on the railway vehicle, comprising:
the railway vehicle includes a power converter that converts power input from the DC link or the plurality of storage batteries into power for driving an auxiliary machine;
When the railcar is switched from a mode driven by power from the plurality of storage batteries to a mode driven by power from the electric rail,
disconnecting the plurality of series-connected storage batteries from the DC link;
connecting the DC link to the electric rail;
when a voltage of the electric power line is greater than a voltage of the plurality of storage batteries connected in series, a first rectifier is used to prevent the power input from being passed in a direction toward the plurality of storage batteries, and a second rectifier is used to pass the power input from the DC link in a direction toward the power converter;
when a voltage of the plurality of storage batteries connected in series is greater than a voltage of the electric rail, the second rectifier does not pass power input from the plurality of storage batteries in a direction toward the electric rail, but passes the power in a direction toward the power converter by the first rectifier;
a driving method for a railway vehicle, comprising: a sequence for switching the series-connected storage batteries to a parallel connection when power input from the DC link is supplied to the power converter; A method for driving a railway vehicle according to any one of claims 7 to 9,
the railway vehicle includes a filter capacitor provided on an input side of the power converter, and a charging circuit provided between the DC link, the plurality of storage batteries, and the filter capacitor;
a charging circuit for charging a filter capacitor to a power converter that is connected to the power converter and that is connected to the power converter;

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