On-board device and electric vehicle driving method

Abstract

To provide a simpler railway system capable of charging a power storage device of an electric motor vehicle by boosting the voltage of a ground charging stand.SOLUTION: A railway system, which operates an electric motor vehicle equipped with a power storage device chargeable by power supplied from ground, keeps a dc charger of a different from a trolley wire arranged on ground, and comprises, as the on-board equipment of the electric motor car, a power converter from at least dc to ac connected from the trolley wire via a collecting device and having a switching element and an electric motor connected to the ac side of the power converter. A dc-dc power converter boosts the output voltage of the dc charger to secure a charging voltage necessary to charge the power storage device by the dc charger. The system has a changeover switch capable of changing over from invertor mode to chopper mode and a chopper circuit formed to be able to be boosted when the dc-dc power converter is an on-board combined purpose machine, but can comprise a special purpose machine.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention car The present invention relates to an electric vehicle driving method and an electric vehicle driving device. [Background technology]

[0002] In recent electric vehicles, in an emergency when the power supply from the overhead lines is cut off, it is considered that the electric vehicle can run for the minimum necessary distance under its own power using power stored in an on-board storage battery. It is preferable that the on-board storage battery be as small as possible in terms of space, weight, and equipment burden, including the charging function. Therefore, an electric vehicle is known in which multiple on-board secondary batteries are connected in parallel, charged from a low-voltage charging device, and these charged secondary batteries are reconnected in series to obtain a high-voltage output (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-225323 Summary of the Invention [Problem to be solved by the invention]

[0004] Battery-powered trains run like regular trains on sections with overhead lines and other electric power supplies, but can run to a certain extent on their own using the power of onboard batteries in sections without electric lines or when the power supply from the electric lines is cut off.Even if the capacity of onboard batteries is limited, if it becomes easier to charge onboard batteries of electric vehicles (Battery Electric Vehicles, hereafter also referred to as "EVs") using a plug-in method from ground-based charging facilities in the future, this will expand the options for train operation plans.

[0005] In this case, the voltage difference between the high-voltage trains and the relatively low-voltage EVs is a problem, and it is desirable to have a simple system that can eliminate this voltage difference. The present invention was made in consideration of the above-mentioned problem, and its purpose is to provide a simpler railway system that can boost the voltage of ground charging stations and charge the electric vehicle's storage device. On-board equipment that can increase facility utilization rates The purpose is to provide [Means for solving the problem]

[0006] The present invention, which solves the above problems, provides an electric vehicle equipped with a power storage device that can be charged by power supplied from the ground. On-board equipment installed in And, electric Connected to the lane via a current collector , the AC side is connected to the motor, At least DC to AC power converter with switching elements of Preparation, It is located above ground and is a separate system from the electric train line. DC charging device 、 The charging voltage required to charge the power storage device is ensured by boosting the output voltage of the DC charging device with a DC-DC power conversion device. [Effects of the Invention]

[0007] According to the present invention, a simpler railway system is provided that can charge the electric storage device of an electric vehicle by boosting the voltage at a charging station on the ground. On-board equipment that can increase facility utilization rates can provide. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a railway system (hereinafter also referred to as "this system") according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic circuit diagram of the system of FIG. 1. [Figure 3] 3 is a timing chart showing the operation of the system of FIGS. 1 and 2 in different modes. [Figure 4] FIG. 3 is a circuit diagram in which the power conversion device of the present system shown in the schematic circuit diagram of FIG. 2 is switched and wired in a three-phase inverter mode. [Figure 5]FIG. 3 is a circuit diagram in which the power conversion device of the present system shown in the schematic circuit diagram of FIG. 2 is switched and wired in a chopper mode. [Figure 6] FIG. 3 is a circuit diagram of a variation of the system of FIGS. 1 and 2. [Figure 7] FIG. 10 is a circuit diagram of a railway system (also referred to as "the system") according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a circuit diagram of a railway system (also referred to as "the system") according to a third embodiment of the present invention. [Figure 9] FIG. 10 is a circuit diagram of a railway system (also referred to as "the system") according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. Embodiment 1 will be described with reference to FIGS. 1 to 6, and a modified example thereof will be described with reference to FIG. 6. Embodiment 2 will be described with reference to FIG. 7. Embodiment 3 will be described with reference to FIG. 8. Power conversion devices 6A to 6D according to these respective embodiments will be described later, but unless distinction is necessary, they will be collectively referred to as power conversion device 6. Reference numeral 6X in the text indicates that power conversion device (inverter) 6 is used as a DC-DC power conversion device (chopper circuit) 6X of a different mode, and is also called a dual-purpose device 6X, but this reference numeral 6X is not shown. [Example]

[0010] FIG. 1 is a schematic diagram showing a railway system according to a first embodiment of the present invention. As shown in FIG. 1, a vehicle 8 receives power from an overhead line 1 via a current collector 7, and is driven by an electric motor 5 to rotate wheels 3, thereby moving forward or backward. The electrical equipment that drives the vehicle 8, namely, the circuit breaker 11a, power conversion device 6A, filter reactor 15, line breaker box, power storage device 9, storage battery 17, and external charging connector 10 as on-board devices, are each stored in separate boxes and disposed under the floor. The filter reactor 15 will be described in detail later.

[0011] Although each electrical component shown in Fig. 1 is shown in a separate box, packaging density may be increased by storing some or all of the electrical components in a single box. The low potential side of the power conversion device 6A is connected to the rail 2 via the wheel 3 as an electrical ground. The electric motor 5 is mounted on a bogie 4, which supports a vehicle 8.

[0012] The motor 5 may be either an induction motor or a permanent magnet synchronous motor. In the case of induction motors, one power converter 6A can drive multiple motors. However, in the case of synchronous motors, one power converter 6A can only drive one motor. The voltage of the overhead line 1 is DC 600V, DC 750V, DC 1500V, DC 3000V, etc. In Example 1, the voltage of the overhead line 1 is DC 1500V. The configuration of this system will be described below.

[0013] Figure 2 is a schematic circuit diagram of the system shown in Figure 1. In this system, power from an overhead line 1 is received by a current collector 7, and the power is supplied to a power converter 6A via a circuit breaker 11a and a filter reactor 15. A charging circuit consisting of contactors 12a and 14a and a charging resistor 13a is mounted between the circuit breaker 11a and the filter reactor 15 as part of the power converter 6A. Note that these charging circuits may be mounted in a box separate from the power converter 6A.

[0014] Power converter 6A has the function of converting DC power received by current collector 7 into AC power, and is composed of switches S1 and S2, a filter capacitor 16, switching elements Q1 to Q6, and anti-parallel freewheeling diodes (hereinafter simply referred to as "diodes") D1 to D6. Switching elements Q1 and Q2 are connected in series to form the U phase.

[0015] Similarly, switching elements Q3-Q4 are connected in series to form a V phase. Similarly, switching elements Q5-Q6 are connected in series to form a W phase. Although power conversion device 6A of the first embodiment will be described as having a two-level circuit configuration as an example, it is also applicable to a multi-level circuit configuration of three or more levels, such as power conversion device 6C shown in FIG. 7 as a second embodiment.

[0016] When the switching elements Q1 to Q6 are IGBTs (Insulated Gate Bipolar Transistors), diodes D1 to D6 connected in antiparallel to the main terminals of each switching element Q1 to Q6 are required. The diodes D1 to D6 allow a return current to flow when each switching element Q1 to Q6 is off.

[0017] On the other hand, if the switching elements Q1 to Q6 are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), the body diodes of the MOSFETs may be used as the diodes D1 to D6. In this way, if the switching elements Q1 to Q6 are MOSFETs or the like and have body diodes, the body diodes of the MOSFETs may be used without connecting diodes in antiparallel to the respective switching elements Q1 to Q6 (this is also applicable to similar elements shown in FIGS. 7 and 8).

[0018] By using the body diodes as free-wheeling diodes, the number of diode chips D1 to D6 can be reduced, thereby enabling the miniaturization of the power conversion device 6A. The other series-connected switching elements Q1 to Q6 (e.g., Q1 and Q2) may be housed in the same package, forming a 2-in-1 package. The switching elements Q1 to Q6 may be MOSFETs, IGBTs, or multi-gate IGBTs (similar elements shown in FIGS. 7 and 8 can also be used).

[0019] The semiconductor materials of the switching elements Q1 to Q6 and the diodes D1 to D6 may be Si (silicon) or semiconductors with wider bandgaps than Si, such as SiC (silicon carbide) or GaN (gallium nitride). These wide bandgap semiconductors can reduce losses compared to Si, allowing for a more compact power converter 6A. (This can also be applied to similar elements shown in FIGS. 7 and 8.)

[0020] This system has a charging circuit consisting of a storage battery 17, its circuit breaker 11b, contactors 12b and 14b, and a charging resistor 13b. The storage battery 17 is connected in parallel to the filter capacitor 16 via the circuit breaker 11b and the charging circuit. Therefore, the voltage of the storage battery 17 and the voltage of the overhead line 1 are roughly the same, 1500V. Therefore, the storage battery 17 can also be charged with power obtained from the overhead line 1.

[0021] If a substation (not shown) that supplies power to the overhead line 1 uses a diode rectifier, power control may not be possible and the overhead line voltage may fluctuate significantly. In such a case, unless some countermeasure is taken in at least one of the substation and the battery-powered electric railcar, there is a risk that an excessive charging current will flow to the battery due to the potential difference between the overhead line 1 and the battery 17. One countermeasure is to install equipment on the substation side that can control the charging power, thereby reducing the excessive charging current.

[0022] As an alternative measure, when the substation is unable to control power due to the diode rectifier described above, the system can also control charging of the storage battery 17 as follows. First, a case where the vehicle 8 is accelerating (powering) will be described. When the vehicle 8 is powering, the system receives power from the overhead line 1 to drive the motor 5, and releases the contactors 12b, 14b or the circuit breaker 11b to disconnect the storage battery 17 from the overhead line 1, thereby controlling the storage battery 17 so that it is not affected by the overhead line 1 whose voltage has dropped due to powering.

[0023] On the other hand, when the vehicle 8 decelerates, the system disconnects it from the overhead line 1 by opening the contactors 12a, 14a or the circuit breaker 11a, and closes the contactor 14b and the circuit breaker 11b, thereby directing the regenerative power from the motor 5 solely to charging the storage battery 17. As described above, even if the substation uses a diode rectifier and the power environment is not necessarily ideal for a battery-powered train, the system can optimally respond to various situations, such as the power supply from the overhead line 1, the traction power demand, the regenerative power supply, and the charging of the storage battery 17, by using the control described above.

[0024] The system also has a DC charging device 20 on the ground. This DC charging device 20 is connected to the power conversion device 6A via an on-board external charging connector 10. The high-potential side of the external charging connector 10 is connected between the contactor 14a and the filter reactor 15, and the low-potential side is connected to the low-potential side of the filter capacitor 16. The output voltage of the DC charging device 20 is lower than the 1500 V voltage of the overhead line 1, and is, for example, 350 V.

[0025] The power conversion device 6A includes switches S1 and S2. The base end of switch S1 is connected to filter reactor 15, and the terminal end is connected to the high potential side of filter capacitor 16. Like switch S1, switch S2 also has a base end connected to filter reactor 15, and the terminal end is connected between switching elements Q1 and Q2, i.e., to the intermediate terminal of the U phase. Note that the base and terminal ends of switches S1 and S2 are designated for convenience in accordance with Figures 2, 6, and 7, and are actually identified by contacts a, b, and c described below.

[0026] In the power conversion device 6A, the end of switch S2 is connected to the intermediate terminal of the U phase, but it may also be the intermediate terminal of the V phase or the W phase. Also, although switches S1 and S2 are a-contact or b-contact switches, they may also be c-contact switches, in which case the switches can be made smaller. Note that the a-contact, b-contact, and c-contact switches are general names for the relationship between relay operation and terminals, and are not shown in the drawings, but are as follows:

[0027] An a-contact is a terminal that connects to the NO (Normally Open) terminal and turns ON when current flows through the coil. A b-contact (Brake Contact) is a terminal that disconnects from the NC (Normally Close) terminal and turns OFF when current flows through the coil. A c-contact is a terminal that connects to the NC terminal (b-contact) when no current flows, and connects to the NO terminal (a-contact) when current flows.

[0028] Figure 3 is a timing chart showing the operation of the system of Figures 1 and 2 in each mode. The horizontal axis of Figure 3 is time, and the vertical axis is, from top to bottom, the vehicle running command, the command of circuit breaker 11a, the command of switch S1, the operation of power converter 6A, the external charging command, and the command of switch S2. The timing chart will be explained below.

[0029] At time t0, in preparation for a command to move the vehicle 8 forward, backward, accelerate, or decelerate, the circuit breaker 11a and the switch S1 are closed.

[0030] At time t1, a vehicle information control device (not shown) turns on a vehicle travel command based on a notch operation by the vehicle driver, and the power conversion device 6A operates in a three-phase inverter mode. Details of the three-phase inverter mode of the power conversion device 6A will be described later.

[0031] At time t2, when the vehicle travel command is turned off, power conversion device 6A also stops operating.

[0032] At time t3, when an external charging command for charging from the DC charging device 20 is turned ON, the mode for charging the storage battery 17 is entered. At this time, the overhead line 1 and the DC charging device 20 have different voltages, so they must be electrically separated, and therefore the circuit breaker 11a is opened. Note that instead of opening the circuit breaker 11a, the contactors 12a and 14a may be opened. Also, the switch S1 is opened and the switch S2 is closed.

[0033] At time t4, power converter 6A starts operating in chopper mode, and charges storage battery 17 via power converter 6A from DC charging device 20. Details of the chopper mode of power converter 6A will be described later.

[0034] Fig. 4 is a circuit diagram in which the power conversion device 6A of the present system shown in the schematic circuit diagram of Fig. 2 is switched and wired in a three-phase inverter mode. When the power conversion device 6A operates in the three-phase inverter mode, the DC charging device 20 is not connected and is therefore not shown. Pulse-shaped AC power is output from the filter capacitor 16 by PWM (Pulse Width Modulation) control of the switching elements Q1 to Q6. This AC power is supplied to the electric motor 5 and converted into mechanical energy, thereby moving the vehicle 8 forward or backward.

[0035] The initial charging of the filter capacitor 16 is performed via the charging resistor 13a by opening the contactor 14a and closing the contactor 12a. When the initial charging of the filter capacitor 16 is completed, the contactor 12a is opened and the contactor 14a is closed. The filter capacitor 16 and the filter reactor 15 form a filter circuit, which reduces the noise current flowing from the power conversion device 6A to the overhead line 1.

[0036] When accelerating the vehicle 8, power is received from the overhead line 1 via the current collector 7, and the power is supplied to the motor 5 via the circuit breaker 11a, the filter reactor 15, and the power converter 6A. Alternatively, if the circuit breaker 11a is opened, the power converter 6A is supplied with power from the storage battery 17, so that the power received from the substation (not shown) connected to the overhead line 1 can be reduced.

[0037] The storage battery 17 may be charged at least when the vehicle 8 is stopped or when it is accelerating (powering). During charging, the charging current of the storage battery 17 can be limited by closing the contactor 12b and opening the contactor 14b to charge via the charging resistor 13b. Alternatively, the storage battery 17 can be rapidly charged without using the charging resistor 13b by opening the contactor 12b and closing the contactor 14b.

[0038] In the case of a braking operation to decelerate the vehicle 8, the electric motor 5 functions as a generator and generates regenerative power. The regenerative power is converted from AC to DC by the power conversion device 6A and is used as power for accelerating (powering) other vehicles (not shown) via the filter reactor 15, the circuit breaker 11a, the current collector 7, and the overhead line 1.

[0039] When charging the storage battery 17 with regenerative power, the circuit breaker 11a or the contactors 12a and 14a may be opened to electrically separate the storage battery 17 from the overhead line 1. At this time, by lowering the brake torque of the electric motor 5 below that during normal operation, the charging current of the storage battery 17 can be limited, thereby suppressing deterioration of the storage battery 17. As described above, when the power conversion device 6A operates in the three-phase inverter mode, the power of the electric motor 5 is controlled when the vehicle 8 moves forward, backward, or accelerates or decelerates.

[0040] Figure 5 is a circuit diagram in which the power converter 6A of the present system shown in the schematic circuit diagram of Figure 2 is switched and wired in chopper mode. The power converter 6A performs equivalent conversion. As described above, the overhead line 1 and the DC charging device 20 are electrically separated by either opening the circuit breaker 11a alone or opening both of the two contactors 12a and 14a.

[0041] When the power conversion device 6A operates in chopper mode, the DC charging device 20 is connected via the external charging connector 10. Here, the filter reactor 15 functions as a boost reactor 15, and the switching elements Q1 and Q2 and the diodes D1 and D2 function as a chopper circuit, thereby forming a boost chopper circuit.

[0042] That is, with respect to the output voltage of DC charging device 20 being 350V, 1500V can be output via a step-up chopper, and storage battery 17 can be charged. At this time, contactor 12b is opened, and contactor 14b and circuit breaker 11b are closed, so that the charging current of storage battery 17 can be controlled by DC charging device 20 without using charging resistor 13b. In addition, a capacitor (not shown) that absorbs ripple current accompanying the switching of switching elements Q1 and Q2 should be mounted at least inside DC charging device 20 and / or power conversion device 6A.

[0043] By incorporating the switches S1 and S2 of this system into the power conversion device 6A, the storage battery 17 can be charged even when the output voltage of the DC charging device 20 is lower than the voltage of the storage battery 17. That is, the power conversion device 6A applies the filter reactor 15 to a boost chopper mode and operates as a DC-DC power conversion device 6X, thereby supplementing the insufficient output voltage of the DC charging device 20. As a result, there is no need to newly install a boost chopper on the vehicle 8 or on the ground side, and this system can be made smaller. Furthermore, as will be described later in Example 2 of FIG. 7, the power conversion device 6A can also perform boost operation with a two-level circuit configuration.

[0044] The power conversion device 6A needs to switch a control unit (not shown) between the three-phase inverter mode and the chopper mode depending on the operation of each mode. In accordance with this switching, it is advisable to change the carrier frequency of the switching elements Q1 to Q6 to an optimum one for the operation of the three-phase inverter mode or the chopper mode. For example, by reducing the carrier frequency in the chopper mode, it is possible to reduce the switching loss of the DC-DC power conversion device 6X and improve the life of the power conversion device 6.

[0045] Here, we consider inductive interference to the motor 5. In the system shown in Figure 2, considering the losses and lifespan of the switching elements Q1 to Q6, the frequency cannot be made extremely high compared to the maximum frequency of inverter operation, even if we want to increase the efficiency of the boost chopper. If there is not much difference in the frequency between the different operating modes, there is also not much difference in the voltage change rate dv / dt related to inductive interference. Furthermore, even if a voltage such as inductive interference due to boost chopper operation is applied to the terminals of the motor 5, the neutral point voltage will be the same value (input voltage Ed / 6) as during inverter operation. Therefore, inductive interference due to leakage current to the motor 5 is not considered to be a problem.

[0046] In the first embodiment shown in FIG. 2, in order to reduce the size of on-board equipment, a step-up chopper is eliminated (avoiding the need for additional components dedicated to step-up), while eliminating the potential difference between the low-voltage output of the DC charging device 20 and the high-voltage of the storage battery 17. Therefore, when one-phase switching elements Q1 and Q2 of the power conversion device (inverter) 6A shown in FIG. 2 are operated as a chopper, a neutral point voltage (Ed / 6) is generated in the motor 5. At this time, the other two-phase switching elements Q1 to Q6 and diodes D11 to D6 are all in the off state, so no current flows in the motor 5. Therefore, there is no risk of the train 8 moving while stopped and charging.

[0047] [Variations] Figure 6 is a circuit diagram of a modified example of the system of Figures 1 and 2. In a power conversion device 6B of the modified example of Figure 6, switches S3 and S4 are added to the power conversion device 6A of the first embodiment, and other configurations are the same as those of the first embodiment, so description thereof will be omitted. The base end of switch S3 is connected to filter reactor 15 in the same way as switch S2, and the end is connected between switching elements Q3 and Q4, i.e., to the intermediate terminal of the V phase.

[0048] The base end of switch S4 is connected to filter reactor 15, similar to switch S3, and the end is connected between switching elements Q5 and Q6, i.e., to the intermediate terminal of the W phase. In power conversion device 6B of Fig. 6, in chopper mode, switches S2, S3, and S4 are closed and switch S1 is opened. As a result, filter reactor 15 functions as boost reactor 15 in power conversion device 6B, and power conversion device 6B becomes DC-DC power conversion device 6X.

[0049] In this DC-DC power converter 6X, the switching elements Q1 to Q6 and diodes D1 to D6 that constitute the U, V, and W phases respectively function as chopper circuits, thereby forming a three-phase boost chopper circuit. This three-phase boost chopper circuit can increase the charging power of the storage battery 17 compared to a one-phase boost chopper circuit, and therefore can charge the storage battery 17 more quickly. [Example]

[0050] 7 is a circuit diagram of a railway system (also referred to as "this system") 6C according to a second embodiment of the present invention. This power conversion device 6C is configured with a three-level inverter. Hereinafter, switching elements will be described using only the reference numerals in FIGS. 2 and 7.

[0051] Here, we will explain the operational flow of charging the on-board storage battery 17 from the DC charging device 20 as wayside equipment. First, switch S2 is turned ON. Regarding the U phase of the three-phase configuration, Q1 in FIG. 2 corresponds to Q1u+Q2u in FIG. 7. Similarly, Q2 in FIG. 2 corresponds to Q3u+Q4u in FIG. 7.

[0052] That is, Q1u + Q2u form the upper arm of the chopper, and Q3u + Q4u form the lower arm of the chopper. The relationship between the switching elements shown in FIG. 2 and the switching elements shown in FIG. 7 is the same for the V and W phases of a three-phase configuration. The advantage of a three-level circuit is that the rated voltage of switching elements Q1u and the like can be significantly reduced compared to a two-level circuit. For example, if the rated voltage of each of switching elements Q1 to Q6 in a two-level circuit is 3300V, then 1700V is sufficient for a three-level circuit. [Example]

[0053] FIG. 8 is a circuit diagram of a railway system (also referred to as "this system") 6D according to a third embodiment of the present invention. This power conversion device 6D is composed of an AC / DC converter and a DC / AC inverter for an AC power section. Here, a flow of charging the storage battery 17 from the AC overhead line 1 or the wayside equipment 20 will be described. When charging from the AC overhead line 1 (for example, 20 kV), first, the contactor 14a is connected. Next, the switching elements Q7 to Q10 operate as converters from AC to DC to charge the storage battery 17.

[0054] The system according to the third embodiment of FIG. 8 has technical features in that the connection points of the DC charging device 20, which is a ground facility, are both ends of the contactor 14a, and also in the following operation flow.

[0055] When charging from DC charging device 20, contactors 12a, 14a and circuit breaker 11a are also opened. At this time, the leakage inductance of transformer 18 corresponds to step-up reactor 15 of the second and third embodiments, and switching elements Q7 to Q10 operate as DC-DC power converter 6X of the second and third embodiments, that is, a DC / DC converter using a chopper circuit. Note that reference numeral 6X (not shown) indicates that reference numeral 6 is used in a different mode.

[0056] Next, Q7 and Q9 are turned ON simultaneously to store energy in the boost reactor 15. By turning Q7 and Q9 OFF simultaneously, the storage battery 17 is charged from D7 and the current returns to the secondary side of the transformer via D10. In this chopper mode, all of the inverters (Q1 to Q6) are in the OFF state. Conventionally, Q7 to Q10 in FIG. 8 only operate as an AC / DC converter, but in the third embodiment, a technical feature is that they also operate as a DC / DC converter capable of boosting. [Example]

[0057] FIG. 9 is a circuit diagram of a railway system (also referred to as "this system") according to a fourth embodiment of the present invention. In the first embodiment of FIG. 2, the power converter 6A is switched from its inverter circuit function to its DC-DC power converter (boost chopper circuit) function by operating switches S1 and S2. In contrast, the fourth embodiment of FIG. 9 differs in that the power converter 6A is fixed to its inverter function, and a power storage device 9F (hereinafter also referred to as a "dedicated device," "DC-DC power converter," or "power storage device") with a dedicated boost chopper circuit pre-installed is provided and used. Another difference is that the first embodiment of FIG. 2 has only one filter reactor 15 in the main circuit, whereas the fourth embodiment of FIG. 9 has three filter reactors. Another difference is that the storage battery 17 can be charged not only from the overhead line 1 but also from a DC charging device 20 via an external charging connector 10. Here, the voltages of the overhead line 1 and the storage battery 17 are assumed to be equal (for example, 1500V), and the voltage of the DC charging device 20 is assumed to be, for example, 350V.

[0058] As shown in Fig. 9, the dedicated boost chopper circuit is composed of switching elements Q11 and Q12, diodes D11 and D12, and a filter capacitor 19. The filter reactor 15a is disposed in the main circuit, as in Fig. 2. The filter reactor 15b is disposed closer to the main circuit than the power storage device 9F.

[0059] 9, when the storage battery 17 is charged by appropriately boosting the voltage from the DC charging device 20, a control unit (not shown) causes the switching elements Q11 and Q12 of the boost chopper circuit to perform chopping operation at an appropriate frequency. When the storage battery 17 is discharged, the control unit turns off the switching elements Q11 and Q12 of the chopper circuit, while turning on the diode D11 in the forward direction.

[0060] As described above, the system of Example 4 in FIG. 9 provides a DC-DC power converter (boost chopper circuit) for the onboard power storage device 9F. This allows the low-voltage DC charging device 20, which is installed on the ground and primarily intended for use in automobiles, to also be used for the high-voltage storage battery 17 used to drive the electric train. This eliminates the potential difference between the two, thereby improving their mutual utilization rates. Furthermore, when charging the storage battery 17 from the overhead line 1, the voltages are at the same level, so the boost chopper circuit can be switched on without switching on the switching element Q11. This reduces the switching loss of the boost chopper and improves charging efficiency. Alternatively, excessive charging current can be suppressed without using a boost chopper by charging the storage battery 17 using the charging resistor 13b.

[0061] [supplement] In recent years, the spread of electric vehicles (EVs) has progressed in line with the global trend toward decarbonization. As a result, if the majority of gas stations are replaced with charging stations in the future, it is expected that charging stations will be installed along railway lines and near stations, even in sparsely populated areas. Furthermore, there is a growing need for rapid charging for EV chargers, and the capacity of charging devices is increasing to the point where they can be supplied to battery-powered trains. For example, the CHAdeMO standard is being established to support 500kW, which is comparable to charging via overhead lines. This raises the question of the relative merits of tank trucks and power lines when it comes to transporting energy to remote areas.

[0062] [Battery train] Even in areas other than remote areas, a safety issue for electric cars 8 is that in sections where emergency evacuation is difficult, such as tunnels or bridges, or between stations, if the power supply from the overhead lines 1 is cut off due to a power outage or other reason, the electric cars are required to be able to move under their own power to a safe area such as the nearest station. Also, since most electric cars 8 have no-stopping positions set up, making it difficult to escape on their own if they stop in dead sections, etc., there is a need for a simple means of self-escape in case they become stranded there. The battery-powered electric car 8 can meet this need.

[0063] [Remote Railway] Furthermore, in order to maintain depopulated lines with less burden, it is also possible to leave the overhead wires 1 only in the necessary sections, remove the overhead wires 1 between the remote areas to reduce the maintenance burden, and operate diesel railcars, battery-powered railcars, or hybrid railcars connecting these two sections. In this case, it is necessary to secure qualified drivers with driver's licenses for different types of locomotives, such as electric railcars, diesel railcars, and hybrid railcars, which increases the burden on personnel even though the number of trains operated is small.

[0064] On the other hand, railway operators want to avoid the burden of requiring drivers to obtain licenses for diesel railcars due to the limited number of routes. Furthermore, if there are no licensing issues, electric railcar drivers can be reassigned to non-electrified sections. Under the current circumstances, it is preferable to allocate personnel solely to those qualified to drive electric railcars, which are relatively easy to secure, or those qualified to drive hybrid electric railcars, which are expected to be the next easiest to secure. In contrast, battery-powered electric railcars 8 that operate on non-electrified sections can often be driven by those who hold an electric railcar license (within the scope of compliance in Japan at the time of application).

[0065] [Reactor] In the electric vehicle 8, the power conversion device 6 controls the current flowing to the electric motor 5 by appropriately combining inverter control, chopper control, etc. using semiconductor switching elements Q1 to Q6 (hereinafter abbreviated as "semiconductors"). If the electric vehicle 8 receives power as DC, the filter reactor 15 is an essential piece of equipment, for the following reasons.

[0066] Devices that use semiconductors for control, such as armature chopper control and VVVF control, perform current control and frequency control by switching and modulating the semiconductors, which in turn generates electrical noise such as harmonics (hereinafter also referred to as "harmonic noise" or "high frequency").

[0067] When this harmonic noise leaks into the overhead wire 1, it causes electromagnetic induction according to the disturbed waveform. If there is a current fluctuation in the overhead wire 1, through which a large current flows that serves as the main power source for the electric vehicle 8, the strength of the magnetic field generated around the overhead wire 1 also fluctuates due to electromagnetic induction, and this magnetic field fluctuation affects the current in the rail 2 laid near the overhead wire 1.

[0068] In addition, most railways employ track circuits that detect the presence of a train in a specific section of the track, thereby activating signaling devices for blocking. A weak current for safety systems such as signals and crossings flows through the rails 2 that form the track circuit. This weak current can fluctuate due to the influence of magnetic field fluctuations in the overhead wires 1 caused by harmonics. This is the inductive interference to the track circuit.

[0069] In this way, when harmonics generated by the power converter 6 flow into the overhead wire 1, they cause inductive interference to the track circuit. As a result, there is a concern that the electrical signals of the signaling safety system and other systems running on the rails 2 may be disrupted, causing malfunctions and other problems. Railway systems are designed to take measures to protect against this inductive interference.

[0070] For this reason, recent semiconductor-controlled railway vehicles (electric cars) 8 have a filter reactor 15 interposed in the electric circuit between the power conversion device 6 and the overhead line 1 as a measure to prevent high-frequency waves from flowing into the overhead line 1. This filter reactor 15 is actually a huge coil that prevents changes in the current flowing therethrough, and this property is used to block out rapidly changing harmonic noise.

[0071] Harmonics are generated not only during regenerative braking when the electric car 8 returns electricity to the overhead wire 1 and rails 2, but also during power running when accelerating with the electric motor 5. The filter reactor 15 can reduce the causes of inductive interference by functioning to remove only harmonics that leak from the power converter 6 to the overhead wire 1 side. On the other hand, almost no harmonics leak from the power converter 6 to the rail 2 side, so no measures are required on that side.

[0072] [DC train and chopper circuit] If the electric car 8 is a DC electric train, the converter circuit, inverter circuit, and chopper circuit can be integrated in the power conversion devices 6A to 6C, and since a filter reactor 15 is present, this can be used to configure a chopper circuit. However, since an AC electric train does not have a filter reactor 15, it is difficult to configure a chopper circuit. However, it is possible to configure a chopper circuit in place of the reactor 15 by applying the leakage reactance associated with the transformer 18, which is essential for AC electric trains. Therefore, this system can also be applied to AC electric trains that run on AC power feeder sections. Note that the high frequency generated by this chopper circuit can be neutralized without using a filter reactor 15.

[0073] This system can be summarized as follows: [1] As shown in Figures 1, 2, 4 to 9, this system is a railway system in which a DC charging device 20, which is a separate system from the electric train line 1, is installed on the ground and which operates electric cars 8 equipped with storage devices 17 that can be charged using power supplied from the DC charging device 20.

[0074] The electric car 8 is equipped with a power converter 6 and an electric motor 5 as on-board equipment. The power converter 6 is connected to the electric railroad line 1 via a current collector 7, has switching elements Q1 to Q6, Q11, and Q12, and converts power at least from DC to AC.

[0075] The electric motor 5 is connected to the AC side, i.e., the inverter output side, of the power conversion device 6. The charging voltage required for charging the power storage device 17 by the DC charging device 20 is ensured by boosting the output voltage of the DC charging device 20 by the DC-DC power conversion devices 6X and 9F.

[0076] When the electric vehicle 8 is mainly powered, the power conversion device 6 is in inverter mode. In charge mode, the low voltage of the on-ground charging stand 20, such as 350 V, is boosted by the DC-DC power conversion devices 6X and 9F to 1500 V, the same as that of the overhead lines, to charge the storage device 9 of the electric vehicle 8. Note that the voltage values ​​shown here are merely examples.

[0077] In this way, the DC-DC power converters 6X and 9F can charge the power storage device 9 by applying a charging voltage of, for example, 1500 V or thereabouts. Therefore, the output voltage of the DC charging device, for example, 350 V, can supplement the charging voltage shortfall of 1150 V via the DC-DC power converters 6X and 9F.

[0078] 2 to 8. For example, as shown in FIG. 9, when charging a high-voltage storage battery 17 from a low-voltage DC charging device 20, a DC-DC power converter (chopper circuit) permanently installed in a power storage device 9F may be activated by a control unit (not shown). In this way, the present invention can provide a simpler railway system that can boost the relatively low voltage of a charging stand 20 on the ground as much as necessary to charge the power storage device 9 of an electric car 8.

[0079] For example, if there is an EV charging station 20 near a terminal station in a remote area, it would be possible to plan efficient train operations by regularly using this as part of the railway system. Conversely, a railway operator may provide a simple DC charging device 20 installed for a battery-powered train 8 in its own railway system as an EV charging station 20 for public use.

[0080] [2] As shown in Fig. 9, in the above [1], a dedicated unit 9F having a permanent chopper circuit may be further provided as an on-board DC-DC power conversion device. That is, the on-board device may be configured with the dedicated unit 9F of Fig. 9 instead of the power storage device 9 of Fig. 2 and Fig. 4 to Fig. 8. The boost function may be provided in at least one of the dual-purpose unit 6X and the dedicated unit 9F, or may be provided in both.

[0081] [3] In the above [1], the DC-DC power converter 6X is a dual-purpose device 6X, and is arranged on the vehicle in a form capable of forming a chopper circuit capable of boosting voltage. The dual-purpose device 6X can be switched from inverter mode to chopper mode. t The dual-purpose device 6X is formed by switching the function of the power conversion device 6 by the switches S1 and S2 when charging the power storage device 17.

[0082] For example, if the power conversion device 6 is a three-phase inverter, the switching elements Q1 to Q2 (one example) constituting at least one phase among the switching elements Q1 to Q6 constituting the three phases and the reactor 15 are used together to form a chopper circuit of the dual-purpose device 6X. The reactor 15 is a wire connection inserted between the current collector 2 and the power conversion device 6 so as to function as a high-frequency filter in the inverter mode. t In the power mode, the element is wired to function as a boost element that prevents current changes while generating a voltage according to the rate of change.

[0083] Furthermore, power conversion device 6 is configured to switch to the function of a chopper circuit and contribute to the boost operation, and is connected to boost the power supplied from DC charging device 20 to the required voltage and charge power storage device 17. In this system, the inverter and the DC boost circuit are not operated simultaneously, so that the number of switching elements Q1 to Q6 required to ensure the current capacity may be switched to be used for the DC boost circuit only when necessary.

[0084] In this system, low-voltage DC power received from a DC charging device 20 is boosted to a required high voltage level by a DC-DC power conversion device 6X and applied to a power storage device 9 of an electric vehicle 8, thereby charging the power storage device 9.

[0085] [4] As shown in Figure 8, the system described in [3] above can also be applied to AC trains running on AC-fed sections, and the leakage reactance of the transformer 18 may be substituted for the reactor 15 to form a chopper circuit.

[0086] [5] As shown in Figures 2 and 7, in the above [3], one end of the reactor 15 is connected to the current collector 2, and the other end is connected to the branch bases of the changeover switches S1 and S2. These changeover switches S1 and S2 are configured to branch the other end of the reactor 15 into contacts for at least two circuits.

[0087] The contacts of one changeover switch S1 (hereinafter also referred to as "switch S1" or "contact S1") are connected to the DC bus of the power conversion device 6, and the contacts of the other changeover switch S2 (contact S2) are connected to the AC side of the power conversion device 6. As shown in FIG. 3, in this system, in inverter mode, which is mainly for powering, switch S1 is ON and switch S2 is OFF, and vice versa, in chopper mode. t In the power mode, the reactor 15 is connected so as to function as a boost element.

[0088] [6] As shown in Figures 2, 4 to 9, in the above [5], the power conversion device 6 is equipped with a two-level or three-level inverter. In the power conversion device 6 equipped with such a two-level or three-level inverter, the switching elements Q1 to Q2 (one example) constituting at least one phase are switched to the function of a chopper circuit and contribute to the boost operation. As a result, this system can boost the relatively low voltage of the charging stand 20 installed on the ground and charge the power storage device 9 of the electric vehicle 8 at the high voltage required by it.

[0089] [7] As shown in Figure 6, in the power conversion device 6 equipped with a three-phase inverter in the above [6], when rapid charging is performed by a terrestrial DC charging device 20, if the switching elements Q1 to Q6 for all phases are switched to a DC boost circuit and used exclusively for that purpose, the current capacity for the three phases will be three times that of one phase.

[0090] As described above, in this system, the inverter and the DC boost circuit are not operated at the same time, so if all of the switching elements Q1 to Q6 required to ensure the current capacity necessary for rapid charging are switched to a powerful DC boost circuit and used exclusively for that purpose, the capabilities of the DC-DC power conversion device 6X can be maximized.

[0091] [8] In the above [6] or [7], the carrier frequency when the power conversion device 6 is operated as an inverter and the carrier frequency when the power conversion device 6 is operated as a DC-DC power conversion device 6X may be optimized for each operation and set to different frequencies.

[0092] Within the frequency range that allows obtaining the desired voltage, the lower the switching frequency, the higher the power conversion efficiency. This is because the total loss in this type of power conversion device is equal to the conduction heat loss when switching is on, plus the loss that occurs each time switching (ON / OFF transition) multiplied by the number of switching times.

[0093] [9] In the above [1], it is preferable that at least one of the switching elements Q1 to Q6 mounted on the power converter 6 has a base material made of a semiconductor material (such as silicon carbide) having a wider band gap than silicon Si. The system equipped with the power converter 6 made of this base material has less heat loss than a base material made of silicon Si, so that for the same power capacity, heat loss can be reduced compared to Si. As a result, the power converter 6 can be made smaller in size in this system.

[0094]

[10] In the above [1], at least one of the switching elements Q1 to Q6 mounted on the power conversion device 6 is preferably a voltage-driven element such as a MOSFET, an IGBT, or a multi-gate IGBT. The present system equipped with the power conversion device 6 having this structure has less heat loss than one without it, and therefore can reduce heat loss for the same power capacity. As a result, the present system can reduce the size of the power conversion device 6.

[0095]

[11] It is preferable that the DC-DC power conversion device 6X, 9F of any one of [1] to

[10] above is an on-board device configured to be mounted on an electric car 8. Such on-board device can boost the low voltage of the charging stand 20 on the ground and charge the power storage device 9 of the electric car 8, thereby increasing the facility utilization rate.

[0096] Furthermore, in sections where electric train lines such as overhead lines 1 remain and where the power supply is maintained, the battery electric train 8 can be charged while running as a normal electric train 8, and even in sections where there are no electric train lines 1 or when the power supply from the electric train lines 1 is cut off, the electric train can run on its own using the power of the onboard batteries 9. Even if the capacity of the onboard batteries 9 is limited, the onboard batteries 9 of the electric train 8 can be easily charged using a plug-in method from ground EV charging equipment 20, which expands the options for train operation plans and increases the reliability of train operations. [Explanation of symbols]

[0097] 1 overhead wire, 2 rail, 3 wheel, 4 bogie, 5 electric motor, 6, 6A to 6D power conversion device, 6X DC-DC power conversion device (DC / DC converter using chopper circuit), 7 current collector, 8 railway vehicle (electric car, battery train, train, vehicle), 9 power storage device, 9F power storage device with DC-DC power conversion device (step-up chopper circuit), 10 external charging, 11a, 11b circuit breaker, 12a, 12b, 14a, 14b contactor, 13a, 13b charging resistor, 15, 15a to 15c filter reactor (step-up reactor), 16, 19 filter capacitor, 17 storage battery, 18 transformer, 20 DC charging device (EV charging stand), Q1 to Q12 switching elements, D1 to D12 diodes, S1 to S4 change-over switch

Claims

1. An on-board device mounted on an electric vehicle having a power storage device that can be charged by power supplied from the ground, a power converter for converting at least DC to AC, the power converter being connected to the electric train line via a current collector, the AC side of the power converter being connected to the electric motor, and having a switching element; a charging voltage required to charge the power storage device by a DC charging device that is installed on the ground and is a system separate from the electric power line is secured by a DC-DC power conversion device that boosts the output voltage of the DC charging device; the DC-DC power converter is a dual-purpose device installed on a vehicle, a selector switch capable of switching from an inverter mode to a chopper mode in the dual-purpose machine; a chopper circuit configured to be capable of boosting voltage; and When charging the power storage device, the power conversion device is switched from an inverter mode to a chopper mode while also serving as a switching element; The power converter is connected to at least one phase thereof so as to be supplied with power from the DC charging device, and operates as a DC-DC power converter. An on-board device characterized by:

2. It is applied to AC trains running in AC powered sections, The chopper circuit is formed by substituting the leakage reactance of a transformer for a reactor. The on-board device according to claim 1.

3. An on-board device mounted on an electric vehicle equipped with a power storage device that can be charged by power supplied from the ground, a power converter for converting at least DC to AC, the power converter being connected to the electric train line via a current collector, the AC side of the power converter being connected to the electric motor, and having a switching element; a charging voltage required to charge the power storage device by a DC charging device that is installed on the ground and is a system separate from the electric power line is secured by a DC-DC power conversion device that boosts the output voltage of the DC charging device; the DC-DC power converter is a dual-purpose device installed on a vehicle, a selector switch capable of switching from an inverter mode to a chopper mode in the dual-purpose machine; a chopper circuit configured to be capable of boosting voltage; and When charging the power storage device, the power converter is formed by using the functions of the power conversion device while also serving as a switching element, a DC-DC power converter connected to at least one phase of the power converter so that power is supplied from the DC charging device, and performing a boost operation as the DC-DC power converter; One end of the reactor is connected to the current collector, and the other end is connected to the branch base of the changeover switch, the changeover switch branches the other end of the reactor into contacts of at least two circuits, one contact being connected to a DC bus of the power conversion device and the other contact being connected to an AC side of the power conversion device; On-vehicle device.

4. The power conversion device includes a three-phase inverter, and when rapid charging is performed by the DC charging device, all phases of the power conversion device operate as the DC-DC power conversion device. The on-board device according to claim 3.

5. a carrier frequency when the power conversion device operates as an inverter is different from a carrier frequency when the power conversion device operates as a DC-DC power conversion device; The on-board device according to claim 3 or 4.

6. A method for driving an electric vehicle having a power storage device that can be charged from a DC charging device that is installed on the ground in a system separate from the electric train line, comprising: The power conversion device provided on the electric vehicle includes: converting the electric power connected to the electric rail via a current collector from at least DC to AC using a switching element and connecting it to an electric motor; When the electric vehicle is powered or regenerated, the electric motor exchanges power with the AC side of the power conversion device, When charging the power storage device, a DC-DC power conversion device boosts the output voltage of the DC charging device and supplies the boosted voltage for charging; the DC-DC power conversion device installed on the vehicle is a dual-purpose device, The dual-purpose machine is The selector switch switches from inverter mode to chopper mode. In the chopper mode, the chopper circuit is configured to be capable of boosting the voltage, When charging the power storage device, the power conversion device is switched from an inverter mode to a chopper mode while also serving as a switching element; The power converter is connected to at least one phase thereof so as to be supplied with power from the DC charging device, and operates as a DC-DC power converter. Electric vehicle driving method.

7. It is applied to AC trains running in AC powered sections, The chopper circuit is formed by substituting the leakage reactance of a transformer for a reactor. The electric vehicle driving method according to claim 6.

8. A method for driving an electric vehicle equipped with a power storage device that can be charged from a DC charging device installed on the ground in a system separate from the electric train line, comprising: The power conversion device provided on the electric vehicle includes: converting the electric power connected to the electric rail via a current collector from at least DC to AC using a switching element and connecting it to an electric motor; When the electric vehicle is powered or regenerated, the electric motor exchanges power with the AC side of the power conversion device, When charging the power storage device, a DC-DC power conversion device boosts the output voltage of the DC charging device and supplies the boosted voltage for charging; the DC-DC power conversion device installed on the vehicle is a dual-purpose device, The dual-purpose machine is The selector switch switches from inverter mode to chopper mode. In the chopper mode, the chopper circuit is configured to be capable of boosting the voltage, When charging the power storage device, the power converter is formed by using the functions of the power conversion device while also serving as a switching element, a DC-DC power converter connected to at least one phase of the power converter so that power is supplied from the DC charging device, and performing a boost operation as the DC-DC power converter; One end of the reactor is connected to the current collector, and the other end is connected to the branch base of the changeover switch, the changeover switch branches the other end of the reactor into contacts of at least two circuits, one contact being connected to a DC bus of the power conversion device and the other contact being connected to an AC side of the power conversion device; Electric vehicle driving method.

9. When rapid charging is performed using the DC charging device, all three phases of the power conversion device including a three-phase inverter operate as a DC-DC power conversion device. The electric vehicle driving method according to claim 8.

10. A carrier frequency when the power conversion device operates as an inverter is made different from a carrier frequency when the power conversion device operates as a DC-DC power conversion device.

10. The electric vehicle driving method according to claim 8 or 9.

Images