Railway vehicle system

Abstract

A railway vehicle system (100) comprises: trucks (2a, 2b); AC electric motors (4a, 4b) mounted on the truck (2a); AC electric motors (7a, 7b) mounted on the truck (2b); and a power conversion device (9) for controlling operation of the AC electric motors (4a, 4b, 7a, 7b). The AC electric motors (4a, 4b) mounted on the truck (2a) are always operated as AC electric motors for running power, and the AC electric motors (7a, 7b) mounted on the truck (2b) are always operated as AC electric motors for regenerative braking.

Description

Railway Vehicle Systems

[0001] The present disclosure relates to a railway vehicle system that runs on power supplied from an overhead line.

[0002] A railway vehicle system is configured with at least one driving car. The driving car has multiple AC motors mounted on bogies and at least one power conversion device that drives the multiple AC motors collectively or individually. Typically, one driving car has two bogies, and each bogie is equipped with two AC motors. The AC motors are, for example, induction motors or synchronous motors. The four AC motors of the two bogies are individually connected to a single power conversion device, or are connected in parallel to a single power conversion device on a bogie-by-bogie or vehicle-by-car basis, to provide driving force to the railway vehicle system. In a railway vehicle system, the multiple AC motors mounted on one or more driving cars basically all have the same structure and are all designed to the same specifications. During power running, one or more driving cars cause all AC motors to generate driving torque, and during regenerative braking, all AC motors generate braking torque. The regenerative power obtained during regenerative braking is supplied via overhead lines so that other railway vehicle systems can use it as traction power, thereby achieving energy conservation among multiple railway vehicle systems.

[0003] Japanese Patent Application Laid-Open No. 2006-129994 discloses a driving force control device for an electric vehicle that maximizes the realization of a desired vehicle motion while appropriately maintaining the driving state of each electric motor. The technology disclosed in Japanese Patent Application Laid-Open No. 2006-129994 discloses a technology that, when it is determined that a mixture of electric motors performing power running and electric motors performing regeneration exists, adjusts the driving force distribution to each electric motor by aligning the positive and negative signs of driving force command values ​​for each electric motor. This technology was developed in consideration of the fact that, in a case where a mixture of electric motors performing power running and electric motors performing regeneration exists, if the starting voltage required for power running differs from the regenerative voltage generated during regeneration, the efficiency of the electric motor when using regenerative power to drive the other electric motor may be significantly reduced, making it impossible to generate the desired torque, or making it difficult to recover power from the regenerative electric motor to the battery.

[0004] JP 2012-16162 A

[0005] Generally, in the design of railway vehicle systems, efforts are made to miniaturize AC motors and optimize the number of motors installed in the entire train set in order to ensure acceleration performance and reduce costs. For this reason, even if conventional railway vehicle systems are appropriately designed as a configuration for obtaining driving torque during powering, it is difficult to say that they are appropriately designed as a configuration for obtaining braking torque during regenerative braking. In fact, at high speeds ranging from the maximum speed when a railway vehicle is traveling to intermediate speeds, they rely on air brake force, which obtains friction by pressing friction material against the wheel tread or rotating disk, and there is a problem in that sufficient braking torque cannot be obtained from the AC motor.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a railway vehicle system that can ensure sufficient braking torque from an AC motor even in high-speed ranges ranging from maximum speed to intermediate speeds when a railway vehicle is traveling.

[0007] In order to solve the above-mentioned problems and achieve the object, a railway vehicle system according to the present disclosure includes first and second bogies, first and second AC motors mounted on the first bogie, third and fourth AC motors mounted on the second bogie, and a power conversion device that controls operation of the first to fourth AC motors. In this railway vehicle system, two of the first to fourth AC motors always operate as AC motors for power running, and the other two, which do not operate as AC motors for power running, always operate as AC motors for regenerative braking.

[0008] According to the railway vehicle system of the present disclosure, sufficient braking torque can be ensured by the AC motor even at high speeds ranging from the maximum speed at which the railway vehicle runs to intermediate speeds, thereby achieving the effect of constructing a system that does not rely on air brake force.

[0009] FIG. 1 is a diagram showing an example of the configuration of a railway vehicle system according to embodiment 1. FIG. 2 is a diagram showing an example of the configuration of a power conversion device according to embodiment 1. FIG. 3 is a diagram showing an example of the configuration of a power conversion device different from FIG. 2 according to embodiment 1. FIG. 4 is a diagram used to explain the design concept of the railway vehicle system according to embodiment 1. FIG. 5 is a diagram used to explain a control curve used by a control unit of the railway vehicle system according to embodiment 1.

[0010] A railway vehicle system according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description, multiple components of the same type will be denoted by reference numerals with subscripts, but when describing these components without distinguishing between them, the subscripts will be omitted as appropriate.

[0011] Embodiment 1. Fig. 1 is a diagram showing an example of the configuration of a railway vehicle system 100 according to embodiment 1. Fig. 1 shows an example in which the railway vehicle system 100 is made up of two driving cars 1, 1a. Fig. 1 does not show other types of cars such as a command car and trailer cars.

[0012] Each driving car 1 includes two bogies 2a, 2b and a power conversion device 9. Two AC motors 4a, 4b are mounted on the bogie 2a. In the first embodiment, the AC motors 4a, 4b are AC motors that always operate as AC motors for power running, and are denoted as "PM (Powering Motor)" in FIG. 1 . Note that always operating as AC motors for power running means that they are intended to function as AC motors for power running, and is not intended to exclude the possibility that an operation that generates regenerative braking torque may temporarily be included in the operation process.

[0013] The AC motors 4a and 4b are designed as AC motors dedicated to power control. The AC motor 4a is connected to a gear 5 via a drive shaft 20, and the wheels 3 of the driving car 1 are connected to the gear 5 via an axle 22. The driving torque of the AC motor 4a is transmitted to the gear 5 via the drive shaft 20. The driving torque transmitted to the gear 5 is transmitted to the wheels 3 via the axle 22, and the wheels 3 are driven to rotate. In the bogie 2a, the AC motor 4b is connected in the same way as the AC motor 4a to a drive shaft different from the drive shaft 20 to which the AC motor 4a is connected.

[0014] Further, two AC motors 7a, 7b are mounted on bogie 2b. In the first embodiment, AC motors 7a, 7b are AC motors that always operate as AC motors for regenerative braking, and are denoted as "BM (Braking Motor)" in Fig. 1. Note that always operating as AC motors for regenerative braking means that they are intended to function as AC motors for regenerative braking, and is not intended to exclude the possibility that an operation that generates powering torque may be temporarily included in the operation process.

[0015] The AC motors 7a and 7b are designed as AC motors dedicated to regenerative braking control. The AC motor 7a is connected to a gear 8 via a drive shaft 20, and the wheels 3 of the driving car 1 are connected to the gear 8 via an axle 22. The braking torque of the AC motor 7a is transmitted to the gear 8 via the drive shaft 20. The braking torque transmitted to the gear 8 is transmitted to the wheels 3 via the axle 22, and braking force is applied to the wheels 3. In the bogie 2b, the AC motor 7b is connected in the same manner as the AC motor 7a to a drive shaft different from the drive shaft 20 to which the AC motor 7a is connected.

[0016] In this paper, one of the two bogies (bogies 2a and 2b in the first embodiment) may be referred to as the "first bogie" and the other as the "second bogie." In addition, in this paper, the four AC motors (AC motors 4a, 4b, 7a, and 7b in the first embodiment) may be referred to as the "first AC motor," the "second AC motor," the "third AC motor," and the "fourth AC motor," respectively. In this paper, gear 5 may be referred to as the "first gear," and gear 8 may be referred to as the "second gear."

[0017] In FIG. 1 , when the direction of the arrow is the traveling direction of the railway vehicle system 100, AC motors 4a, 4b and AC motors 7a, 7b are arranged in driving car 1a so that they are symmetrical to driving car 1 with respect to the traveling direction. Note that if there are driving cars other than driving cars 1, 1a, these driving cars are arranged between driving car 1 and driving car 1a. That is, in FIG. 1 , driving car 1 is the driving car located at the front end in the traveling direction, and driving car 1a is the driving car located at the rear end in the traveling direction. With this arrangement, even if the traveling direction of the railway vehicle system 100 is reversed from that in FIG. 1 , the symmetry between driving car 1a, located at the front end in the traveling direction, and driving car 1, located at the rear end in the traveling direction, is maintained. Note that the reason for this arrangement will be described later.

[0018] 2 is a diagram illustrating an example of the configuration of a power conversion device 9a according to embodiment 1. The power conversion device 9a includes an input circuit 15, a common inverter circuit 18, an output switch 19 that switches the output destination of the common inverter circuit 18, and a control unit 6a.

[0019] 2 , one end of the input side of the input circuit 15 is connected to an overhead line 24, and the other end of the input side is connected to a rail 26 that applies a ground potential via a wheel 25. The DC side, which is the output side of the input circuit 15, is connected to a common inverter circuit 18. The AC motors 4a and 4b for power running are connected to one output terminal of an output switch 19, and the AC motors 7a and 7b for regenerative braking are connected to the other output terminal of the output switch 19. In the case of an individual drive system in which one AC motor is driven by one inverter circuit, one of the AC motors 4a and 4b for power running is connected to one output terminal of the output switch 19, and the other AC motor 4b or 4a for power running is connected to one output terminal of the output switch 19 in another power conversion device 9a. In addition, one of the AC motors 7a, 7b for regenerative braking is connected to the other output terminal of the output switch 19, and the other AC motor 7b or 7a for regenerative braking is connected to the other output terminal of the output switch 19 in the other power conversion device 9a.

[0020] The overhead line 24 may be a DC overhead line or an AC overhead line. When the overhead line 24 is an AC overhead line, a main transformer is provided on the input side of the input circuit 15. DC power or AC power output from the overhead line 24 is supplied to the input terminal of the input circuit 15, and DC power generated at the output terminal of the input circuit 15 is supplied to the common inverter circuit 18. In addition, regenerative power generated in the common inverter circuit 18 is supplied to the overhead line 24 side via the input circuit 15 so that other railway vehicle systems 100 can use it as drive power.

[0021] The control unit 6a controls the connection destination of the output switch 19 so that the common inverter circuit 18 and the powering AC motors 4a, 4b are electrically connected when the railway vehicle system 100 is accelerating. Furthermore, the control unit 6a controls the connection destination of the output switch 19 so that the common inverter circuit 18 and the regenerative braking AC motors 7a, 7b are electrically connected when the railway vehicle system 100 is decelerating. As a result, the output switch 19 switches the output destination of the common inverter circuit 18 to the powering AC motors 4a, 4b when accelerating, and switches the output destination of the common inverter circuit 18 to the regenerative braking AC motors 7a, 7b when decelerating.

[0022] The power conversion device 9a shown in Fig. 2 may be configured as shown in Fig. 3. Fig. 3 is a diagram showing an example configuration of a power conversion device 9b according to the first embodiment, which is different from that shown in Fig. 2. The power conversion device 9b includes an input circuit 15, a power running AC motor inverter circuit 16, a regenerative braking AC motor inverter circuit 17, and a control unit 6b. The power running AC motor inverter circuit 16 is an inverter circuit dedicated to powering control, and the regenerative braking AC motor inverter circuit 17 is an inverter circuit dedicated to regenerative braking control. Components that are the same as or equivalent to those in Fig. 2 are denoted by the same reference numerals. Differences from Fig. 2 will be described below.

[0023] 3, the DC side, which is the output side of the input circuit 15, is connected to a powering AC motor inverter circuit 16 and a regenerative braking AC motor inverter circuit 17. Powering AC motors 4a, 4b are connected to the powering AC motor inverter circuit 16, and regenerative braking AC motors 7a, 7b are connected to the regenerative braking AC motor inverter circuit 17. In the case of the individual drive system, one powering AC motor 4a or 4b is connected to the powering AC motor inverter circuit 16, and the other powering AC motor 4b or 4a is connected to the powering AC motor inverter circuit 16 provided in another power conversion device 9b. In the case of the individual drive system, one of the AC motors 7a or 7b for regenerative braking is connected to the inverter circuit 17 for the AC motor for regenerative braking, and the other AC motor 7b or 7a for regenerative braking is connected to the inverter circuit 17 for the AC motor for regenerative braking provided in another power conversion device 9b.

[0024] DC power or AC power supplied from the overhead line 24 side is supplied to the input terminal of the input circuit 15, and DC power generated at the output terminal of the input circuit 15 is supplied to the inverter circuit 16 for the powering AC motor. In addition, regenerative power generated in the inverter circuit 17 for the regenerative braking AC motor is supplied to the overhead line 24 side via the input circuit 15 so that other railway vehicle systems 100 can use it as drive power.

[0025] When the railway vehicle system 100 accelerates, the control unit 6b controls the powering AC motors 4a, 4b using the powering AC motor inverter circuit 16, and when the railway vehicle system 100 decelerates, the control unit 6b controls the regenerative braking AC motors 7a, 7b using the regenerative braking AC motor inverter circuit 17.

[0026] Next, a description will be given of the design concept of the railway vehicle system 100 according to the first embodiment. Fig. 4 is a diagram illustrating the design concept of the railway vehicle system 100 according to the first embodiment.

[0027] The lower part of Fig. 4 shows a torque curve representing the design concept according to the first embodiment, and the upper part of Fig. 4 shows a torque curve representing the design concept according to the prior art as a comparative example. The left side of each figure shows a torque curve for powering torque, and the right side of each figure shows torque curves for brake torque and air brake force. The horizontal axis of each figure represents the speed of the railway vehicle, and in the torque curves for brake torque and air brake force, the positive direction of the horizontal axis represents the direction in which the speed decreases.

[0028] In the prior art, powering control uses both VVVF (Variable Voltage Variable Frequency) control and CVVF (Constant Voltage Variable Frequency) control in order to ensure acceleration performance, reduce the size of AC motors, optimize the number of motors installed in the entire train, and reduce costs. VVVF control is performed in the low- and medium-speed range from zero speed to the VVVF terminal speed, while CVVF control is performed in the high-speed range from the VVVF terminal speed to maximum speed. Furthermore, in the prior art, in order to use a single AC motor for both powering control and regenerative braking control, the switching speed for switching the brake torque characteristics in the regenerative braking control is set to a speed approximately equal to the VVVF terminal speed. As a result, the hatched area in the upper right diagram is a region dependent on air brake force, and the area of ​​this region is large. For this reason, the design concepts of the prior art have had limitations in pursuing size and cost reduction of AC motors while ensuring acceleration performance and optimizing the number of motors.

[0029] In contrast, in the first embodiment, as described above, the four AC motors 4a, 4b, 7a, and 7b are divided into AC motors 4a and 4b that always operate as powering AC motors and AC motors 7a and 7b that always operate as regenerative braking AC motors, so that the latter AC motors can be designed by considering only the braking torque characteristics without considering the powering torque characteristics. Note that the torque characteristics of the former AC motors are set to be equivalent to those of the prior art, as shown in the left diagram in the lower part of Figure 4.

[0030] In the diagram on the right side of the lower part of Figure 4, the hatched area is the region that depends on the air brake force, and it can be seen that the area of ​​this region is smaller than in the diagram on the right side of the upper part of Figure 4. The reason for this is that the switching speed at which the brake torque characteristics are switched can be designed to approach the maximum speed. This makes it possible to pursue miniaturization and cost reduction of AC motors while ensuring acceleration performance and optimizing the number of motors.

[0031] Next, a description will be given of the control curves used by the control units 6a and 6b of the railway vehicle system 100 according to embodiment 1. Fig. 5 is a diagram illustrating the control curves used by the control units 6a and 6b of the railway vehicle system 100 according to embodiment 1.

[0032] The left side of Fig. 5 shows a control curve according to the prior art, and the right side of Fig. 5 shows a control curve according to the first embodiment. The upper side of each figure shows a control curve relating to the powering characteristics, and the lower side of each figure shows a control curve relating to the regenerative braking characteristics. The horizontal axis of each figure represents the speed of the railway vehicle, and the vertical axis of each figure represents torque, voltage, or current. In each figure, the solid line represents powering torque or regenerative torque, the dashed line represents the voltage applied to the AC motors 4 and 7, and the dashed-dotted line represents the current flowing through the AC motors 4 and 7. The meanings of the VVVF terminal speed, maximum speed, and switching speed are as explained using Fig. 4.

[0033] As shown on the left side of Figure 5, in the prior art, the same control curve is used for the powering characteristics and the regenerative braking characteristics, from the viewpoint of using a single AC motor for both powering control and regenerative braking control. In contrast, in the first embodiment, the powering AC motor 4 and the regenerative braking AC motor 7 are used separately, allowing the regenerative braking AC motor 7 to be designed separately. Figure 5 shows an example in which the control curve for the powering characteristics is the same as in the prior art, and the control curve for the regenerative braking characteristics is set to the maximum speed. With such characteristics, the constant power region as in the prior art is eliminated, and only the constant torque region can be used. This makes it possible to ensure sufficient braking torque even in the high-speed range using the regenerative braking AC motor 7.

[0034] Returning to the explanation of Fig. 3, the power conversion device 9b shown in Fig. 3 is configured to include an inverter circuit dedicated to powering control and an inverter circuit dedicated to regenerative braking control, and with this configuration, the following control can be performed.

[0035] When accelerating the railway vehicle system 100, the control unit 6b controls the traction AC motors 4a, 4b to generate traction torque and controls the regenerative braking AC motors 7a, 7b to a free-run state. When decelerating the railway vehicle system 100, the control unit 6b controls the regenerative braking AC motors 7a, 7b to generate braking torque and controls the traction AC motors 4a, 4b to a free-run state. In this document, this control will be referred to as "first control" as appropriate.

[0036] Next, the operation of the power conversion device 9b under the first control will be considered. For example, if the railway vehicle is a commuter train, subway, or the like, it will travel in a traveling pattern in which it accelerates rapidly after departure, coasts, and then stops at a station with a rapid deceleration. Therefore, a typical traveling pattern for a railway vehicle is assumed to be one cycle consisting of departure from the station, powering, coasting, braking, and stopping. In this typical traveling pattern, the effective value of the motor current flowing through the AC motor is IM. Furthermore, the effective value of the motor current flowing during powering is IMP, and the effective value of the motor current flowing during regenerative braking is IMB. Furthermore, it is assumed that the effective values ​​of the motor current during one powering and one regenerative braking are approximately the same, and the coasting time and stopping time are assumed to be 0 (seconds) for simplicity of calculation.

[0037] Under the above premise and assumptions, when AC motors of a conventional railway vehicle are operated for both power running and regenerative braking, the following equation (1) holds: IMP = 0.5 × IM, IMB = 0.5 × IM (1) In this case, the current borne by the two AC motors is given by the following equation (2): 2 × (IMP + IMB) = 2 × (0.5 × IM + 0.5 × IM) = 2 × IM (A) (2)

[0038] In contrast to this, consider a case where one of two AC motors of a railway vehicle is operated exclusively as an AC motor for powering, and the other is operated exclusively as an AC motor for regenerative braking. In this case, in the first control described above, one AC motor for powering bears the motor current of the two AC motors during powering, but since it coasts during regenerative braking, it does not bear the motor current during regenerative braking. As a result, this AC motor for powering bears the motor current of the following equation (3) during powering: 2×IMP+0×IMB=2×IMP (3)

[0039] In the first control described above, one AC motor for regenerative braking bears the motor current of two AC motors during regenerative braking, but since it coasts during power running, it does not bear the motor current during power running. As a result, this AC motor for regenerative braking bears the motor current of the following equation (4) during regenerative braking: 0×IMP+2×IMB=2×IMB (4)

[0040] Therefore, the motor current borne by one AC motor for powering and one AC motor for regenerative braking under the first control is expressed by the following equation (5): 2×IMP+2×IMB=2×0.5×IM+2×0.5×IM=2×IM (5)

[0041] As described above, equation (5) and equation (2) are equal, and it can be seen that the burden on the motor current is the same as in the prior art even when the railway vehicle system 100 according to embodiment 1 is adopted. Furthermore, when the railway vehicle system 100 according to embodiment 1 is adopted, it is only necessary to change the control curve related to the regenerative braking characteristics, and there is no need to change the control curve related to the powering characteristics, so it can be said that this can be implemented relatively easily.

[0042] Furthermore, when the power conversion device 9b shown in FIG. 3 is used, the following control can be performed instead of the first control described above.

[0043] When accelerating the railway vehicle system 100, the control unit 6b controls the traction AC motors 4a, 4b to generate traction torque, while controlling the regenerative braking AC motors 7a, 7b not to generate torque and to match the drive frequency of the regenerative braking AC motors 7a, 7b to the drive frequency of the traction AC motors 4a, 4b. When decelerating the railway vehicle system 100, the control unit 6b controls the regenerative braking AC motors 7a, 7b to generate brake torque, while controlling the traction AC motors 4a, 4b not to generate torque and to match the drive frequency of the traction AC motors 4a, 4b to the drive frequency of the regenerative braking AC motors 7a, 7b. In this document, this control is referred to as "second control" as appropriate.

[0044] When the second control is implemented, during acceleration, the regenerative braking AC motors 7a, 7b are driven in accordance with the drive frequency of the traction AC motors 4a, 4b, so that the operation of the regenerative braking AC motors 7a, 7b can be prevented from interfering with the acceleration of the railway vehicle system 100. Furthermore, since the regenerative braking AC motors 7a, 7b do not generate torque, it is possible to significantly reduce losses due to the regenerative braking AC motors 7a, 7b. Similarly, during deceleration, the traction AC motors 4a, 4b are driven in accordance with the drive frequency of the regenerative braking AC motors 7a, 7b, so that the operation of the traction AC motors 4a, 4b can be prevented from interfering with the deceleration of the railway vehicle system 100. Furthermore, since the traction AC motors 4a, 4b do not generate torque, it is possible to significantly reduce losses due to the traction AC motors 4a, 4b.

[0045] Next, a supplementary description will be given regarding the gear 5 to which the powering AC motor 4 is connected and the gear 8 to which the regenerative braking AC motor 7 is connected. In configuring the railway vehicle system 100, these gears 5 and 8 can essentially be identical. However, using the same gears 5 and 8 may impose a burden on the design of the regenerative braking AC motor 7, the common inverter circuit 18, and the regenerative braking AC motor inverter circuit 17. Considering these burdens, the gear 5 to which the powering AC motor 4 is connected and the gear 8 to which the regenerative braking AC motor 7 are connected may have different structures. One consideration is the gear ratio of the gears 5 and 8. For example, it is possible to consider setting the gear ratio of the gear 8 to which the regenerative braking AC motor 7 is connected to be smaller than that of the gear 5 to which the powering AC motor 4 is connected. By setting the gear ratio of the gear 8 smaller than that of the gear 5, the rotation speed of the regenerative braking AC motor 7 can be made lower than that of the powering AC motor 4. In this case, when compared at the same rotation speed, a larger current flows through the regenerative braking AC motor 7 than through the powering AC motor 4. However, by suppressing the rotation speed, there is an advantage that regenerative braking characteristics can be pursued that maintain constant torque up to high speeds, as shown in FIG. 5.

[0046] Next, considerations for forming a train using driving cars 1 and 1a will be described. In FIG. 1 , the driving car located at the front end in the direction of travel is designated as driving car 1, and the driving car located at the rear end in the direction of travel is designated as driving car 1a. When traveling in the rain, water droplets between the wheels of a railway vehicle and the rails make them prone to skidding when braking. On the other hand, it is said that the wheels most prone to skidding are those located at the front end in the direction of travel, while wheels located at the rear end in the direction of travel are less likely to skid than wheels located at the front. The reason for this is thought to be that water droplets are removed by the wheels located at the front end in the direction of travel of the vehicle.

[0047] In the configuration shown in Figure 1, when the train is traveling in the direction of the arrow, the bogie 2a of the driving car 1 equipped with the AC motors 4a and 4b for powering is located at the front end in the direction of travel, and as a result, the two bogies 2b of the driving cars 1 and 1a equipped with the AC motors 7a and 7b for regenerative braking are located towards the center of the train. This makes it possible to reduce the occurrence of wheel flats due to skid.

[0048] In addition, in the configuration shown in Figure 1, when the direction of travel is reversed from the direction of the arrow in the figure, the bogie 2a of the driving car 1a equipped with the AC motors 4a and 4b for powering is located at the frontmost position in the direction of travel. Therefore, even if the direction of travel is reversed, the relationship in which the two bogies 2b of the driving cars 1 and 1a equipped with the AC motors 7a and 7b for regenerative braking are located at the center of the train configuration is maintained. Therefore, with the configuration shown in Figure 1, it is possible to reduce the occurrence of wheel flats due to skids even if the direction of travel is reversed.

[0049] Next, a hardware configuration for realizing the functions of the control units 6a and 6b in embodiment 1 will be described with reference to Figures 6 and 7. Figure 6 is a block diagram showing an example of a hardware configuration for realizing the functions of the control units 6a and 6b in embodiment 1. Figure 7 is a block diagram showing another example of a hardware configuration for realizing the functions of the control units 6a and 6b in embodiment 1.

[0050] When realizing some or all of the functions of the control units 6a and 6b in embodiment 1, the configuration can include a processor 300 that performs calculations, a memory 302 that stores programs read by the processor 300, and an interface 304 that inputs and outputs signals, as shown in Figure 6.

[0051] The processor 300 is an example of a computing unit. The processor 300 may be a computing unit called a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). Examples of the memory 302 include non-volatile or volatile semiconductor memory such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), and electrically programmable read-only memory (EEPROM), as well as a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, and a digital versatile disk (DVD).

[0052] The memory 302 stores a program that executes the functions of the control units 6a and 6b in embodiment 1. The processor 300 exchanges necessary information via the interface 304, executes the program stored in the memory 302, and refers to the table stored in the memory 302, thereby performing the above-mentioned processing. The calculation results by the processor 300 can be stored in the memory 302.

[0053] 7 can be used to realize part of the functions of the control units 6a and 6b in the first embodiment. The processing circuit 303 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information input to and output from the processing circuit 303 can be exchanged via an interface 304.

[0054] It is also possible that some of the processing in the control units 6 a and 6 b is performed by the processing circuit 303 , and the processing that is not performed by the processing circuit 303 is performed by the processor 300 and the memory 302 .

[0055] As described above, the railway vehicle system according to the first embodiment includes first and second bogies, first and second AC motors mounted on the first bogie, third and fourth AC motors mounted on the second bogie, and a power conversion device that controls the operation of the first to fourth AC motors. Two of the first to fourth AC motors always operate as AC motors for traction, and the other two, which do not operate as traction AC motors, always operate as AC motors for regenerative braking. According to the railway vehicle system configured in this manner, the AC motors for regenerative braking can be designed separately from the AC motors for traction. Therefore, sufficient braking torque can be ensured by the regenerative AC motors even at high speeds ranging from the maximum speed to intermediate speeds when the railway vehicle is traveling. This has the effect of enabling the construction of a railway vehicle system that does not rely on air brake force.

[0056] In the railway vehicle system according to the first embodiment, when the AC motor for powering is connected to the drive shaft via a first gear and the AC motor for regenerative braking is connected to the drive shaft via a second gear, the second gear may be configured to have a smaller gear ratio than the first gear. With this configuration, the maximum rotation speed of the AC motor for regenerative braking can be made smaller than the maximum rotation speed of the AC motor for powering, thereby achieving the effect of enabling the AC motor for regenerative braking to achieve regenerative braking characteristics that maintain constant torque up to high speeds.

[0057] Furthermore, in the railway vehicle system according to the first embodiment, when a train is made up of multiple driving cars, the first bogie of the driving car located at the forefront in the direction of travel is the bogie located at the front in the direction of travel, and the first bogie of the driving car located at the rearmost in the direction of travel is the bogie located at the rear in the direction of travel. In this way, when a train is made up of multiple driving cars, the two bogies equipped with AC motors for regenerative braking are located at the center of the train. This reduces the impact of water droplets between the wheels and the rails on rainy days, thereby reducing the occurrence of wheel flats due to sliding.

[0058] Furthermore, the railway vehicle system according to the first embodiment can be constructed without relying on air brake force, and the occurrence of wheel flats due to skidding can be reduced. This allows the replacement cycle of friction materials for obtaining air brake force and the work cycle of wheel rolling to be extended, thereby reducing maintenance work.

[0059] Embodiment 2. Fig. 8 is a diagram showing an example of the configuration of a railway vehicle system 100a according to embodiment 2. Fig. 8 shows an example in which the railway vehicle system 100a is made up of two driving cars 1b. In Fig. 8, other types of cars such as command cars and trailer cars are not shown. Note that components that are the same as or equivalent to those in Fig. 1 are given the same reference numerals, and overlapping descriptions will be omitted as appropriate.

[0060] Each driving car 1b includes two bogies 10a, 10b and a power conversion device 9. The power conversion device 9 may be configured as either the power conversion device 9a shown in FIG. 2 or the power conversion device 9b shown in FIG. 3. The bogie 10a is equipped with one AC motor 4 for power running and one AC motor 7 for regenerative braking. The bogie 10b is similarly equipped with one AC motor 4 for power running and one AC motor 7 for regenerative braking. As in the first embodiment, the AC motor 4 for power running is connected to gear 5, which is a first gear, via a drive shaft 20, and the AC motor 7 for regenerative braking is connected to gear 8, which is a second gear, via the drive shaft 20.

[0061] In Figure 8, when the direction of the arrow is the traveling direction of the railway vehicle system 100a, the driving cars 1b are symmetrical with respect to the traveling direction, as in embodiment 1. Furthermore, in the configuration of Figure 8, in the bogie 10a located furthest forward in the traveling direction, the regenerative braking AC motor 7 is disposed further rearward in the traveling direction than the powering AC motor 4. Therefore, the railway vehicle system 100a according to embodiment 2 can achieve the same effect as the railway vehicle system 100 according to embodiment 1 in terms of reducing the occurrence of wheel flats.

[0062] In the railway vehicle system 100 according to the first embodiment, in order to obtain the effect of reducing the occurrence of wheel flats, the driving cars 1 and 1a had to be coupled together so that the bogies 2b carrying the AC motors 7 for regenerative braking were located toward the center of the train formation, but the railway vehicle system 100a according to the second embodiment does not have such a restriction. Therefore, the railway vehicle system 100a according to the second embodiment has the effect of making it easier to form a train than the railway vehicle system 100 according to the first embodiment.

[0063] As described above, in the railway vehicle system according to the second embodiment, one of the first and second AC motors mounted on the first bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking, and one of the third and fourth AC motors mounted on the second bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking. According to the railway vehicle system configured in this manner, as in the first embodiment, the AC motor for regenerative braking can be designed separately from the AC motor for power running. This allows sufficient braking torque to be ensured by the AC motor for regenerative braking, thereby achieving the effect of constructing a railway vehicle system that does not rely on air brake force.

[0064] Furthermore, in the railway vehicle system according to the second embodiment, when a train is made up of multiple driving cars, the AC motor for regenerative braking can be connected to the drive shaft on the center side in the direction of travel of each of the first and second bogies, and the AC motor for powering can be connected to the drive shaft on the outside in the direction of travel of each of the first and second bogies. With this configuration, when a train is made up of multiple driving cars, the AC motor for powering is connected to the drive shaft on the outside in the direction of travel of the bogie that is at the forefront in the direction of travel, making it possible to reduce the occurrence of wheel flats due to skid, as in the first embodiment.

[0065] Furthermore, in the railway vehicle system according to the second embodiment, when the AC motor for powering is connected to the drive shaft via a first gear and the AC motor for regenerative braking is connected to the drive shaft via a second gear, the second gear can be configured to have a smaller gear ratio than the first gear. With this configuration, the maximum rotation speed of the AC motor for regenerative braking can be made smaller than the maximum rotation speed of the AC motor for powering, and therefore, similar to the first embodiment, the effect of being able to pursue regenerative braking characteristics that keep torque constant up to high speeds in the AC motor for regenerative braking can be obtained.

[0066] Embodiment 3. Figure 9 is a diagram showing an example of the configuration of a railway vehicle system 100b according to embodiment 3. Figure 9 shows an example in which the railway vehicle system 100b is made up of a driving car 1c and a driving car 1d. Figure 9 does not show other types of vehicles such as a command car and trailer cars. Note that components that are the same as or equivalent to those in Figure 1 are given the same reference numerals, and overlapping descriptions will be omitted where appropriate.

[0067] The driving car 1c includes two bogies 12a and 12b and a power conversion device 9. The power conversion device 9 may be configured as either the power conversion device 9a shown in FIG. 2 or the power conversion device 9b shown in FIG. 3. Two AC motors 13 are mounted on the bogie 12a, and two AC motors 13 are also mounted on the bogie 12b. Meanwhile, the two AC motors 13 mounted on the bogie 12a are connected to gear 5 via drive shafts 20, and the two AC motors 13 mounted on the bogie 12b are connected to gear 8 via drive shafts 20. These four AC motors 13 are designed as AC motors for both power running control and regenerative braking control.

[0068] The driving vehicle 1d also includes two bogies 10a and 10b and a power converter 9. The power converter 9 may be configured as either the power converter 9a shown in Fig. 2 or the power converter 9b shown in Fig. 3.

[0069] The relationship between the driving cars 1c and 1d in the railway vehicle system 100b is the same as the relationship between the driving cars 1 and 1a in the railway vehicle system 100 of the first embodiment. That is, the two AC motors 13 that always operate as AC motors for power running are mounted on the bogie 12a, which is the first bogie, and the two AC motors 13 that always operate as AC motors for regenerative braking are mounted on the bogie 12b, which is the second bogie. Therefore, the railway vehicle system 100b according to the third embodiment can achieve the same effects as the railway vehicle system 100 according to the first embodiment.

[0070] Furthermore, in the railway vehicle system 100b according to the third embodiment, the AC motor 13 is designed as an AC motor that is used both for powering control and regenerative braking control, which makes it possible to reduce the burden on design compared to the first and second embodiments. Furthermore, in the railway vehicle system 100b according to the third embodiment, the two AC motors 13 for regenerative braking are connected to gear 8 having a smaller gear ratio than gear 5 to which the two AC motors 13 for powering are connected, which has the advantage that it is easier to obtain regenerative braking characteristics that maintain constant torque up to high speeds compared to the two AC motors 13 for powering.

[0071] 9, when the direction of the arrow is the traveling direction of the railway vehicle system 100b, the driving cars 1c and 1d are symmetrical with respect to the traveling direction, as in the first embodiment. In addition, the configuration in FIG. 9 also satisfies the relationship that the regenerative braking AC motor 13 is disposed further rearward in the traveling direction than the powering AC motor 13. Therefore, the railway vehicle system 100b according to the third embodiment can achieve the same effect as the first embodiment in terms of reducing the occurrence of wheel flats.

[0072] As described above, in the railway vehicle system according to the third embodiment, of the first to fourth AC motors designed as AC motors for both powering control and regenerative braking control, the first and second AC motors mounted on the first bogie and always operating as powering AC motors are connected to the drive shaft via a first gear, and the third and fourth AC motors mounted on the first bogie and always operating as regenerative braking AC motors are connected to the drive shaft via a second gear having a smaller gear ratio than the first gear. According to the railway vehicle system configured in this manner, the maximum rotation speeds of the third and fourth AC motors always operating as regenerative braking AC motors can be made lower than the maximum rotation speeds of the first and second AC motors always operating as powering AC motors. This ensures sufficient brake torque by the third and fourth AC motors, thereby achieving the effect of constructing a railway vehicle system that does not rely on air brake force.

[0073] Furthermore, in the railway vehicle system according to the third embodiment, when a train is made up of multiple driving cars, the first bogie of the driving car located at the forefront in the direction of travel is the bogie located at the front in the direction of travel, and the first bogie of the driving car located at the rearmost in the direction of travel is the bogie located at the rear in the direction of travel. In this way, when a train is made up of multiple driving cars, the two bogies equipped with AC motors that always operate as AC motors for regenerative braking are located at the center of the train. This reduces the impact of water droplets between the wheels and the rails on rainy days, thereby reducing the occurrence of wheel flats due to sliding.

[0074] Fourth Embodiment. Figure 10 is a diagram showing an example of the configuration of a railway vehicle system 100c according to a fourth embodiment. Figure 10 shows an example in which the railway vehicle system 100c is made up of two driving cars 1e. Figure 10 does not show other types of cars such as command cars and trailer cars. Note that components that are the same as or equivalent to those in Figures 1 and 9 are given the same reference numerals, and overlapping descriptions will be omitted where appropriate.

[0075] Each driving car 1e is equipped with two bogies 14a, 14b and a power conversion device 9. The four AC motors 13 mounted on the two bogies 14a, 14b of the two driving cars 1e are AC motors used for both power running control and regenerative braking control, as shown in FIG. 9. The power conversion device 9 may be configured as either the power conversion device 9a shown in FIG. 2 or the power conversion device 9b shown in FIG. 3. One of the two AC motors 13 mounted on the bogie 14a is an AC motor that always operates as a power running AC motor, and the other is an AC motor that always operates as a regenerative braking AC motor. The same is true for the bogie 14b, where one of the two AC motors 13 mounted on the bogie 14b is an AC motor that always operates as a power running AC motor, and the other is an AC motor that always operates as a regenerative braking AC motor. In addition, in the bogies 14a and 14b, the two AC motors 13 that always operate as AC motors for powering are connected to gear 5, which is the first gear, via drive shafts 20, and the two AC motors 13 that always operate as AC motors for regenerative braking are connected to gear 8, which is the second gear, via drive shafts 20.

[0076] In Figure 10, when the direction of the arrow is the traveling direction of the railway vehicle system 100c, the relationship in which the driving cars 1e are symmetrical with respect to the traveling direction is the same as in Embodiments 1 to 3. Furthermore, in the configuration of Figure 10, in the bogie 14a located at the forefront in the traveling direction, the AC motor 13 that always operates as an AC motor for regenerative braking is also satisfied, being disposed further rearward in the traveling direction than the AC motor 13 that always operates as an AC motor for powering. Therefore, the railway vehicle system 100c according to Embodiment 4 can achieve the same effect as the railway vehicle systems 100 according to Embodiments 1 to 3 in terms of reducing the occurrence of wheel flats.

[0077] In the railway vehicle system 100b according to the third embodiment, in order to obtain the effect of reducing the occurrence of wheel flats, the driving cars 1c and 1d had to be coupled together so that the bogies 12b equipped with the AC motors 13 that always operate as AC motors for regenerative braking were located toward the center of the train formation, but such a restriction does not exist in the railway vehicle system 100c according to the fourth embodiment. Therefore, the railway vehicle system 100c according to the fourth embodiment has the effect of making train formation easier than the railway vehicle system 100b according to the third embodiment.

[0078] As described above, in the railway vehicle system according to the fourth embodiment, among the first to fourth AC motors designed as AC motors for both powering control and regenerative braking control, one of the first and second AC motors mounted on the first bogie always operates as the powering AC motor and the other always operates as the regenerative braking AC motor, and one of the third and fourth AC motors mounted on the second bogie always operates as the powering AC motor and the other always operates as the regenerative braking AC motor. The two AC motors that always operate as powering AC motors are connected to the drive shaft via first gears, and the two AC motors that always operate as regenerative braking AC motors are connected to the drive shaft via second gears that have a smaller gear ratio than the first gears. According to the railway vehicle system configured in this manner, the maximum rotation speed of the AC motors that always operate as regenerative braking AC motors can be made lower than the maximum rotation speed of the AC motors that always operate as powering AC motors. This allows sufficient braking torque to be ensured by the AC motor that always operates as an AC motor for regenerative braking, making it possible to achieve the effect of building a railway vehicle system that does not rely on air brake force.

[0079] Furthermore, in the railway vehicle system according to the fourth embodiment, when a train is made up of a plurality of driving cars, the AC motors operating as regenerative braking AC motors can be connected to the drive shafts on the center side in the direction of travel of each of the first and second bogies, and the AC motors operating as powering AC motors can be connected to the drive shafts on the outside in the direction of travel of each of the first and second bogies. With this configuration, when a train is made up of a plurality of driving cars, the AC motor operating as powering AC motor is connected to the drive shaft on the outside in the direction of travel of the foremost bogie in the direction of travel, so that it is possible to reduce the occurrence of wheel flats due to skid, as in the third embodiment.

[0080] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0081] 1, 1a, 1b, 1c, 1d, 1e driving cars, 2a, 2b, 10a, 10b, 12a, 12b, 14a, 14b bogies, 3 wheels, 4, 4a, 4b, 7, 7a, 7b, 13 AC motors, 5, 8 gears, 6a, 6b control units, 9, 9a, 9b power conversion devices, 15 input circuits, 16 inverter circuits for AC motors for powering, 17 inverter circuits for AC motors for regenerative braking, 18 common inverter circuits, 19 output switches, 20 drive shafts, 22 axles, 24 overhead lines, 25 wheels, 26 rails, 100, 100a, 100b, 100c railway vehicle systems, 200 processors, 202 memories, 203 processing circuits, 204 interfaces.

Claims

1. A railway vehicle system including first and second bogies, first and second AC motors mounted on the first bogie, third and fourth AC motors mounted on the second bogie, and a power conversion device that controls operations of the first to fourth AC motors, two of the first to fourth AC motors always operate as AC motors for power running; The other two, which do not operate as AC motors for power running, always operate as AC motors for regenerative braking. A railway vehicle system characterized by:

2. the first and second AC motors mounted on the first bogie always operate as AC motors for power running, The third and fourth AC motors mounted on the second bogie always operate as AC motors for regenerative braking.

2. The railway vehicle system according to claim 1.

3. the AC motor for power running is connected to a drive shaft via a first gear, the regenerative braking AC motor is connected to a drive shaft via a second gear; The second gear has a smaller gear ratio than the first gear.

3. The railway vehicle system according to claim 2.

4. When there are a plurality of driving cars each having the first to fourth AC motors and a train is made up of the plurality of driving cars, the first bogie of the driving vehicle located at the frontmost side in the traveling direction is the bogie located at the front side in the traveling direction, The first bogie of the driving vehicle positioned at the rearmost side in the traveling direction is the bogie positioned at the rear side in the traveling direction.

3. The railway vehicle system according to claim 2.

5. one of the first and second AC motors mounted on the first bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking; One of the third and fourth AC motors mounted on the second bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking.

2. The railway vehicle system according to claim 1.

6. the regenerative braking AC motor is connected to a drive shaft on a center side in a traveling direction of each of the first and second bogies, The AC motor for power running is connected to the drive shaft on the outer side in the traveling direction of each of the first and second bogies.

6. The railway vehicle system according to claim 5.

7. the AC motor for power running is connected to a drive shaft via a first gear, the regenerative braking AC motor is connected to a drive shaft via a second gear; The second gear has a smaller gear ratio than the first gear.

7. The railway vehicle system according to claim 6.

8. the AC motor for power running is designed as an AC motor exclusively for power running control, The AC motor for the regenerative brake is designed as an AC motor exclusively for regenerative brake control.

2. The railway vehicle system according to claim 1.

9. the first to fourth AC motors are designed as AC motors for both power running control and regenerative braking control; the first and second AC motors are connected to a drive shaft via a first gear; the third and fourth AC motors are connected to a drive shaft via a second gear; The second gear has a smaller gear ratio than the first gear.

2. The railway vehicle system according to claim 1.

10. the first and second AC motors mounted on the first bogie always operate as AC motors for power running, The third and fourth AC motors mounted on the second bogie always operate as AC motors for regenerative braking.

10. The railway vehicle system according to claim 9.

11. When there are a plurality of driving cars each having the first to fourth AC motors and a train is made up of the plurality of driving cars, the first bogie of the driving vehicle located at the frontmost side in the traveling direction is the bogie located at the front side in the traveling direction, The first bogie of the driving vehicle positioned at the rearmost side in the traveling direction is the bogie positioned at the rear side in the traveling direction.

11. The railway vehicle system according to claim 10.

12. one of the first and second AC motors mounted on the first bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking; One of the third and fourth AC motors mounted on the second bogie always operates as an AC motor for power running, and the other always operates as an AC motor for regenerative braking.

10. The railway vehicle system according to claim 9.

13. the AC motor operating as the regenerative braking AC motor is connected to a drive shaft on a center side in a traveling direction of each of the first and second bogies, The AC motors operating as the AC motors for power running are connected to the drive shafts on the outer sides in the traveling direction of each of the first and second bogies.

13. The rail vehicle system according to claim 12.

14. The power conversion device includes a common inverter circuit and an output switch that switches an output destination of the common inverter circuit, The output switch switches the output destination of the common inverter circuit to the AC motor for powering during acceleration, and switches the output destination of the common inverter circuit to the AC motor for regenerative braking during deceleration.

14. The railway vehicle system according to claim 1, wherein the railway vehicle system comprises:

15. the power conversion device includes an inverter circuit dedicated to powering control and an inverter circuit dedicated to regenerative braking control, During acceleration, the inverter circuit dedicated to powering control is used to control the AC motor for powering, During deceleration, an inverter circuit dedicated to the regenerative brake control is used to control the AC motor for the regenerative brake.

14. The railway vehicle system according to claim 1, wherein the railway vehicle system comprises:

16. The power conversion device is During acceleration, the AC motor for powering is controlled to generate a powering torque, and the AC motor for regenerative braking is controlled to a free-running state; During deceleration, the regenerative braking AC motor is controlled to generate a braking torque, and the powering AC motor is controlled to a free-run state.

16. The rail vehicle system according to claim 15.

17. The power conversion device is During acceleration, the AC motor for powering is controlled so as to generate a powering torque, while the AC motor for regenerative braking is controlled so as not to generate a torque, and the drive frequency of the AC motor for regenerative braking is controlled so as to match the drive frequency of the AC motor for powering, During deceleration, the AC motor for regenerative braking is controlled to generate a brake torque, while the AC motor for power running is controlled not to generate a torque, and the drive frequency of the AC motor for power running is controlled to match the drive frequency of the AC motor for regenerative braking.

16. The rail vehicle system according to claim 15.

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