Railroad converter station linked to MVDC distribution system and its simulation method

Abstract

To provide a simulation system of a railway system for a Medium-Voltage Direct Current (MVDC) distribution network.SOLUTION: In the simulation system, a converter station model simulates a converter station included in the MVDC distribution network, a train operation model simulates an operation state of a train, and a converter controller controls a DC / DC converter included in the converter station model. The simulation system includes a Hardware In the Loop Simulation (HILS) device which performs a simulation based on the converter station model, the train operation model and the converter controller. The converter station model and the train operation model are executed in software by the HILS device, and the converter controller is connected to the HILS device and driven to control the converter station model.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a railway converter station connected to an MVDC power distribution system and a simulation method thereof. [Background technology]

[0002] Figure 1 shows a conventional DC railway system.

[0003] A typical DC railway system in Korea is connected to the AC 22.9kV bus of the distribution system provided by Korea Electric Power Co. Such a system steps down AC 22.9kV to AC 1180V through a rectifier-type transformer, and then converts this to DC 1620V on a no-load basis using a rectifier such as a silicon diode to supply the railway system.

[0004] However, recently, as the proportion of renewable energy sources has increased, the need to increase the capacity of distribution lines has been raised, but due to complaints and other factors, it is not easy to increase the capacity of distribution lines.

[0005] As a result, research is being conducted into methods that can apply DC rather than AC to power distribution systems, making it possible to expand voltage from the perspective of insulation level, and increase current capacity by eliminating the skin effect.

[0006] Currently, there are three standard voltages in Korea, including transmission voltages of 765KV, 345KV, and 154KV, and distribution voltages of special high voltage 22.9KV, and low voltage 380V and 220V. MVDC (Medium-Voltage Direct Current) technology is a technology that converts AC to DC before transmitting electricity in the distribution network, or supplies DC power directly to users, and is defined as (special) high voltage DC distribution in the range of DC 1500V or more and 100KV or less. As a result, the MVDC voltage range is linked to the 22.9KV distribution system before the transformer on the consumer side.

[0007] 1.Necessity of a Virtual Simulation System for DC Railway Converter Stations

[0008] Since this DC railway system is connected as a load to the 22.9 kV bus of the distribution system supplied by Korea Electric Power Corporation, when applying MVDC technology to the distribution system, the railway substation, which is the connection point with the distribution system, of the DC railway system must also be changed to an MVDC connection infrastructure. In other words, in order to convert the high-voltage DC voltage of the distribution system of Korea Electric Power Corporation to railway operating voltages (3000V, 1500V, 750V) and ensure operational flexibility, a DC / DC converter-based DC railway converter station capable of converter-based active voltage control must be developed.

[0009] Therefore, the present invention provides a method for configuring a railway converter station required for connecting a railway system to an MVDC power distribution network, and a method for virtually simulating a core component, a train, as a moving load, in a software environment using only controller hardware in order to pre-verify the converter station without on-site testing.

[0010] 2.Need to improve simulation algorithms

[0011] Meanwhile, the algorithm used in simulating the DC rail converter station also needs to be improved. That is, in order to implement virtual operation based on real-time simulation without using actual railcars, real-time performance must be guaranteed, and a high-speed calculation-based power simulation technique is required to simulate the DC railroad system including the railcars, which are moving loads.

[0012] Looking at conventional power simulation technology, traction and braking force curves created based on the design performance values ​​of electric motors used in railway vehicle design were used, and a batch processing-based train running simulation was used in which all vehicle data, operation data, and track data (curves, gradients, and station position information) were input and all calculations were performed at once for the entire given route using a time accumulation, distance accumulation, or speed accumulation method.

[0013] This is a common application of conventional technology, where the results of a batch-processing train running simulation (speed profile and power profile) are input again and a power simulation is performed to calculate the current and voltage of each node using programming or simulation tools.

[0014] In other words, the biggest feature of the conventional technology is sequential data processing, which means collecting bounded data for a certain period (by line or by several hours or minutes) and processing it sequentially at a certain point in time.

[0015] FIG. 2 is a flow chart showing a conventional power simulation process.

[0016] As shown in FIG. 2, the entire power simulation process is roughly divided into a train running calculation process and a power simulation process, which operate as separate calculation algorithms.

[0017] First, when train running calculation is started, all train data input information such as vehicle data, operation data, and track data (curves, gradients, and stop station location information) are input and parameterized, and train operation pre-processing is first performed. The train operation pre-processing uses the above train data input information in the process of pre-calculating reverse-turnaround switching points and turnaround-braking switching points.

[0018] First, the reverse-to-opposite switching point is appropriately selected taking into consideration the train's operating requirements and environment, but is not selected separately for sections with short distances between stations (meaning a set of a starting station, an ending station, and the next destination station).Then, the opposite-to-braking switching point is determined by considering the positions of each station, which is the starting and ending point of the train, obtaining a train speed trajectory through forward running taking into consideration the tractive force curve, obtaining a train speed trajectory through reverse running taking into consideration the characteristics of the braking force curve, and obtaining the opposite-to-braking switching point at the intersection of these two trajectories.

[0019] Next, train running calculations are started based on the results of the calculated train operation pre-processing. First, acceleration is calculated taking into account tractive force or braking force and running resistance, and the time and value are simultaneously stored in the form of a table / array. Then, speed and position are calculated using acceleration and a preset unit time (sample time), and simultaneously stored in the form of a lookup table or array. Then, power consumption values ​​are calculated and stored using these values. At this time, power consumption can be calculated based on the product of tractive force and speed, or the product of braking force and speed.

[0020] Then, by referring to the lookup table derived in the train operation pre-processing, if a reversing / alternating / braking mode switch occurs, the mode is switched and the tractive force is set to a positive value when reversing, 0 when alternating, and negative when braking, and recalculated, otherwise the process is repeated. If an interruption condition occurs or the value of the train's current position is exactly the same as the value of the stop station, the algorithm ends.

[0021] Next, a power simulation process, which is a separately prepared algorithm, is performed. Power simulation includes both cases where a simulation tool that is modeled and operated separately is used, and cases where a solution is obtained by solving differential equations numerically. First, initial values ​​and conditions are set, and the values ​​of the lookup table (array) of power consumption derived previously in the train running calculation process are read and parameterized, or are read for each accumulated time. Then, the current of the train power consumption is converted and input to an equivalent model (including a mathematical model) expressed in a current circular or impedance type. Then, a coefficient matrix is ​​calculated through the configuration of a state space equation. Finally, the output of a continuous or discrete time system is derived in the form of voltage, current, and power values ​​through the calculation of the state space equation, and is saved and terminated. In summary, the conventional technology has three modes (states) - reverse, forward, and braking - and is characterized by being switchable, and all of these must be calculated in advance for each section between stations.

[0022] The conventional batch or bulk processing train running simulation method has a problem in that it is difficult to query data in real time. In other words, in the batch processing method, other work, i.e., power simulation process, cannot be performed before the train running calculation process is completed. In particular, when the processing method is used for real-time railway power simulation, it may affect accuracy and the size of input data.

[0023] On the other hand, when the batch method is used for real-time simulation, the results of the train running simulation using the batch processing method are temporarily stored in cache memory before the simulation and then used during the real-time simulation. Therefore, in the case of large data, there are limitations to storage and use, and there are also limitations to high-speed calculation of the real-time simulation.

[0024] 3. The need to improve DC / DC converters in converter stations

[0025] DAB (Dual Active Bridge) converters are widely used for bidirectional power conversion in various industrial fields such as railway vehicles, electric vehicles, and solar power generation systems that require the reuse of regenerative power. DAB converters, which have a symmetric dual bridge switching stack with a series inductor in between, have advantages such as structural simplicity, ZVS turn-on characteristics of all switches on the primary and secondary sides, and natural direction change.

[0026] However, typical DAB converters have the problem that they are prone to losing their ZVS characteristics when the load is small, and when the load increases, the conduction loss increases due to the reactive power components present in the circuit.

[0027] To solve this problem, a series-resonant DAB converter (SRDAB) has been proposed, which adds a series inductor and a tuned resonant capacitor. Like conventional DAB converters, SRDAB has many advantages, such as being able to easily adjust the magnitude and flow of power by adjusting the phase difference between the two bridges, and maintaining ZVS characteristics over a wide range.

[0028] However, the resonant / non-resonant DABs known to date are generally constructed based on a full-bridge (FB) or half-bridge (HB), and the switching voltage that can be handled by the two-level based topology is low, at several hundred volts or less. To switch high voltages of DC 1500V or more, such as in railway vehicles, a modular structure with an ISOP (Input-Series-Output-Parallel) structure is required, in which such DAB converters are stacked in series and the outputs are bundled in parallel. However, such a structure requires a large number of switching elements, and passive elements are added to each unit module, increasing the number of active / passive elements structurally.

[0029] Figure 3 shows a typical two-level FB-based SRDAB converter, and Figure 4 shows a typical SRDAB converter combined in an ISOP structure.

[0030] The converter in Figure 3 is two-level based, so the switching voltage that each switch can withstand is the input source voltage Vdc. The converter circuit shown is composed of four switches on the input side, four switches on the output side, a resonant inductor Lr, a resonant capacitor Cr, a transformer with a winding ratio of n:1, input / output filter capacitors, and a load resistor R.

[0031] As mentioned above, since the input terminal is configured in a two-level based FB configuration, in order to apply it to a power conversion system with a high input source voltage such as a railway vehicle, it is necessary to have an ISOP (Input-Series-Output-Parallel) structure.

[0032] As shown in Figure 4, an ISOP structure can be used in which two unit converters as shown in Figure 3 are stacked in series on the input side and two are configured in parallel on the output side. The entire circuit is composed of eight input-side switches, eight output-side switches, four resonant elements (inductors, capacitors), two transformers, two input capacitors, and one output capacitor. It can be seen that the number of input switches and resonant elements is doubled when configuring such an ISOP. In addition, since the input is configured in series, it can be seen that a separate control means is required to control the neutral point fluctuation of the capacitor. [Prior art documents] [Patent documents]

[0033] [Patent Document 1] Republic of Korea Patent No. 10-2213266 (Name of invention: Arrangement method and system for urban railway traffic regenerative braking energy recovery device) Summary of the Invention [Problem to be solved by the invention]

[0034] An object of the present invention is to provide an MVDC distribution system-connected railway converter station for use in a DC railway system and a simulation system therefor.

[0035] Another object of the present invention is to provide a train running simulation device and method that can be used in a railway converter station connected to an MVDC distribution system used in a DC railway system.

[0036] Another object of the present invention is to provide a series resonant DAB converter that can be used in a railway converter station connected to an MVDC distribution system used in a DC railway system, and a control method thereof.

[0037] However, the technical problem that the present embodiment aims to achieve is not limited to the above-mentioned technical problem, and other technical problems may exist. [Means for solving the problem]

[0038] As a technical means for achieving the above technical objectives, according to one aspect of the present invention, a simulation system for a railway system for an MVDC power distribution network includes: a computing device storing a simulation program including a converter station model simulating a converter station included in the MVDC power distribution network and a train running model simulating a running state of a train operating with power supplied from the converter station; a converter controller controlling a DC / DC converter included in the converter station model; and a Hardware In the Loop Simulation (HILS) device performing a simulation based on the converter station model, the train running model, and the converter controller, wherein the converter station model and the train running model are executed as software in the HILS device, and the converter controller is connected to the HILS device and driven to control the converter station model.

[0039] In accordance with another aspect of the present invention, there is provided a method for simulating a railway system for an MVDC power distribution network, comprising the steps of: executing, as software, a simulation program in a Hardware In the Loop Simulation (HILS) device; the simulation program includes a converter station model that simulates a converter station included in the MVDC power distribution network, and a train running model that simulates a running state of a train that operates with power supplied from the converter station; and connecting a converter controller that controls a DC / DC converter included in the converter station model to the HILS device and driving the converter controller to control the converter station model. Effect of the Invention

[0040] According to the above-mentioned means for solving the problems, the present invention proposes a configuration and method for performing a railway system HILS verification method using an actual controller, thereby enabling operational algorithms to be verified in advance for a railway system without on-site testing or a final completed product. By analyzing the results of the virtual simulation obtained in this way and utilizing them in the production and performance testing of actual rolling stock, efficient optimization can be achieved.

[0041] In addition, by applying the present invention, it is possible to easily establish a system operation plan by introducing a large number of railcars having similar operation patterns. In addition, it is not necessary to consider the time interval of the train operation simulation, and time synchronization with the power simulation environment is possible. In addition, while conventional train operation and power simulation technologies input a train schedule and simulate the operation of a large number of railcars, the present invention makes it possible to output and generate a train schedule. In addition, since the input data itself is small enough to be variable, it is possible to create and install the state machine-based stream-type train running high-speed calculation module of the present invention in the traction inverter controller and configure it in the same way as an actual railroad operation environment. In addition, since it is driven on a state machine basis, it is highly stable. In other words, a train has only one state at a time, the flow always flows only as designed, and the state transitions only by predetermined events.

[0042] In addition, the configuration of the series resonant DAB converter proposed in the present invention has the effect of reducing the number of active and passive elements of the primary bridge to half that of the conventional FB under the same withstand voltage conditions. Meanwhile, a special switching sequence is required to realize the proposed method, but the present invention solves this by presenting a special sequence for neutral point balancing control using a switching pattern of a voltage magnitude modulation method instead of the conventional phase transition method. [Brief description of the drawings]

[0043] FIG. 1 shows a conventional DC railway system.

[0044] FIG. 2 is a flow chart showing a conventional power simulation process.

[0045] Figure 3 shows a typical two-level FB-based SRDAB converter.

[0046] Figure 4 shows a typical SRDAB converter combined in an ISOP structure.

[0047] FIG. 5 is a diagram illustrating a configuration of a railway system for an MVDC power distribution network according to an embodiment of the present invention.

[0048] FIG. 6 is a block diagram showing the configuration of a simulation system for a railway system with respect to an MVDC power distribution network according to an embodiment of the present invention.

[0049] FIG. 7 is a block diagram showing the configuration of a computing device included in a simulation system according to an embodiment of the present invention.

[0050] FIG. 8 is a flowchart showing the operation of a train running model based on a stream processing method according to an embodiment of the present invention.

[0051] 9 to 12 are diagrams illustrating a train running calculation process based on a state machine according to an embodiment of the present invention.

[0052] FIG. 13 is a diagram showing a calculation result of a train running model according to an embodiment of the present invention.

[0053] FIG. 14 is an illustration of an equivalent model of a railway system used in a train running model according to an embodiment of the present invention.

[0054] FIG. 15 shows the analysis process of an equivalent model of a railway system used in a train running model according to an embodiment of the present invention.

[0055] FIG. 16 shows a series resonant DAB converter applied to a converter station model according to an embodiment of the present invention.

[0056] FIG. 17 shows an ISOP connection state of a series resonant type DAB converter to which a converter station model according to an embodiment of the present invention is applied.

[0057] FIG. 18 is a diagram illustrating the operation of the series resonant DAB converter according to an embodiment of the present invention.

[0058] FIG. 19 shows primary / secondary leg voltage waveforms of a series resonant DAB converter according to an embodiment of the present invention.

[0059] FIG. 20 shows a case where a switching sequence of a general phase transition method is applied to the present invention.

[0060] 21 and 22 show switching sequences of a pulse magnitude modulation scheme for driving a series resonant DAB converter according to the present invention.

[0061] FIG. 23 shows the relationship between the carrier and the PWM command value in the method for driving the series resonant DAB converter according to one embodiment of the present invention.

[0062] FIG. 24 shows a process of selecting a command mode (CM) in a method of driving a series resonant DAB converter according to an embodiment of the present invention.

[0063] 25 to 27 are block diagrams of a control logic for outputting a control signal of a series resonant DAB converter according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] Hereinafter, with reference to the accompanying drawings, embodiments of the present application will be described in detail so that a person having ordinary skill in the art to which the present application pertains can easily carry out the present application. However, the present application may be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present application in the drawings, parts that are not related to the description are omitted, and similar parts are designated by similar reference numerals throughout the specification.

[0065] Throughout this specification, a part being "connected" to another part includes not only a part being "directly connected" to another part, but also a part being "electrically connected" to another part via another element therebetween.

[0066] Throughout this specification, when an element is said to be "on" another element, "located" refers not only to an element that is in contact with another element, but also to an element that is present between the two elements.

[0067] Throughout this specification, when a part "comprises" a certain component, it means that it can further include other components, not excluding other components, unless otherwise specified. The terms "about," "substantially," and the like, which are used throughout this specification, are used in a numerical value or a close approximation to the numerical value when manufacturing and material tolerances inherent in the referred meaning are presented, and are used to prevent unscrupulous infringers from unfairly taking advantage of the disclosure in which precise or absolute numerical values ​​are recited to aid in the understanding of this application. The terms "step of" or "step of" which are used throughout this specification do not mean "step for".

[0068] In this specification, the term "module" includes a unit implemented by hardware or software, and a unit implemented by using both hardware and software, and one unit may be implemented by using two or more pieces of hardware, and two or more units may be implemented by one piece of hardware. On the other hand, the term "module" is not limited to software or hardware, and the "module" may be configured to reside on an addressable storage medium or to execute one or more processors. Thus, by way of example, the term "module" includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The components and functions provided within the "module" may be combined into fewer components and "modules" or further separated into additional components and "modules".

[0069] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings and the accompanying claims. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numerals refer to like elements throughout the specification.

[0070] FIG. 5 is a diagram illustrating a configuration of a railway system for an MVDC power distribution network according to an embodiment of the present invention.

[0071] In FIG. 5, the left side shows a conventional DC railway system, and the right side shows a DC railway system according to the present invention.

[0072] The DC rail system according to the present invention converts the DC voltage of the distribution grid into rail operating voltage via a DC / DC converter-based DC rail converter station, which uses DC / DC converters capable of converter-based active control.

[0073] Meanwhile, testing of the newly developed DC railway converter station requires on-site testing using actual railway infrastructure during the power equipment development process. This poses a significant risk of train service interruptions or personal injuries if an accident occurs during the testing process, while also posing problems of low efficiency due to the difficulty of repeating tests.

[0074] In addition, confirmation and optimization of system performance using actual railway vehicles requires a lot of time and financial support, and there are limitations to various tests and iterative tests depending on the testbed environment.

[0075] Therefore, in order to conduct safe repeated testing to confirm the performance of new systems (power equipment) and to analyze the same, it is necessary to develop a HILS platform based on a laboratory-scale real-time simulator and controller hardware, and then develop virtual operation technology that can evaluate the performance of the operational efficiency of the target power equipment according to the purpose of using the electrical equipment.

[0076] That is, the dc / dc converter controller of the converter station is implemented in hardware, and the other parts are implemented in a software-based virtual environment to enable virtual operation.

[0077] In order to realize virtual operation based on real-time simulation without using actual railway vehicles, real-time performance must be guaranteed, and a high-speed calculation-based power simulation technique is required to simulate a DC railway system including vehicles, which are moving loads.

[0078] FIG. 6 is a block diagram showing the configuration of a simulation system for a railway system with respect to an MVDC power distribution network according to an embodiment of the present invention.

[0079] The illustrated simulation system (10) includes a computing device (100), a HILS device (200), and a converter controller (300).

[0080] The computing device (100) stores a simulation program including a converter station model that simulates a converter station included in an MVDC power distribution network and a train running model that simulates the running state of a train that operates using power supplied from the converter station.

[0081] The Hardware In the Loop Simulation (HILS) device (200) is a device that enables various simulations to be performed during the development process of a real-time embedded system. The HILS device (200) performs simulations by mathematically modeling the operating environment and system of the equipment to be tested. The HILS device (200) itself corresponds to the conventional technology, and the present invention uses the HILS device (200) to simulate a converter station. For the HILS device (200), the converter controller (300), which is the actual hardware controller of the railway system to be tested, must operate under the illusion that it is in the real environment, so it is essential to build a real-time simulation environment.

[0082] The converter controller (300) includes a processor equipped with control logic for controlling the DC / DC converter, which is the core component of the converter station to be tested. The converter controller (300) performs control operations of the DC / DC converter in cooperation with a real-time simulator IO (e.g., a DI (PWM) card) of the HILS device (200). As a processor, for example, a processor such as an MCU or FPGA may be included in the converter controller (300), and the specific configuration of the control logic will be described later.

[0083] FIG. 7 is a block diagram showing the configuration of a computing device included in a simulation system according to an embodiment of the present invention.

[0084] The computing device (100) includes a processor (110) and a memory (120), and may further include a communications module (130) and a database (140).

[0085] A simulation program is recorded in the memory 120. The simulation program includes a converter station model that simulates a converter station included in the MVDC power distribution network and a train running model that simulates the running state of a train that runs on power supplied from the converter station.

[0086] The memory 120 also performs a function of temporarily or permanently storing data processed by the processor 110. Here, the memory 120 may include a volatile storage medium or a non-volatile storage medium, but the scope of the present invention is not limited thereto.

[0087] The processor 110 executes a simulation program stored in the memory 120. The processor 110 also performs various control operations for the operation of the computing device 100. The processor 110 may refer to a data processing device built into hardware having a circuit physically structured to perform a function expressed by a code or command included in a program. Examples of data processing devices built into hardware include a microprocessor, a central processing unit (CPU), a processor core, a multiprocessor, an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a graphics processing unit (GPU), etc., but the scope of the present invention is not limited thereto.

[0088] The communications module 130 may include one or more components that allow it to send and receive various types of data to and from external computing devices. The communications module 130 may be a device that includes the necessary hardware and software to send and receive signals, such as control or data signals, to and from other network devices over wired or wireless connections.

[0089] The database (140) can manage various data required for executing the simulation program.

[0090] Now, let us look at the detailed configuration of the simulation program.

[0091] As described above, the simulation program includes a converter station model and a train running model, and in response to a user request, the train running model and the converter station model are uploaded to the HILS device (200) so that the train running model and the converter station model are executed, respectively. The train running simulation program operates as the train running model is executed, and the converter station simulation program operates as the converter station model is executed. Then, assuming that the converter station model is installed in the DC railway system, a train running simulation is performed according to the train running model.

[0092] Offline simulation requires tens of hours of calculation to realize a simulation time of a few minutes at most.In contrast, real-time simulation using a real-time simulator shows the same realized time as the actual time (1 second in the simulation is the same as 1 second in the actual time) and can perform simulations from tens of minutes to several hours, making it highly useful for pre-verification.

[0093] 1. Train running simulation program configuration

[0094] The train running model is embodied as a moving load in a real-time simulator according to train running calculation logic, and a high-speed calculation-based power simulation technique is required to simulate the virtual operation of a DC railway system.

[0095] First, considering the accuracy of the train running model, if the simulation results are very long compared to the power system response (time constant, in the range of tens of microseconds) with a calculation interval (Ttps) of around 1 second, the control sampling frequency or control time interval (Tc) of the converter station controller can also be included as a major control variable. Therefore, depending on the relationship between the calculation interval (Ttps), the time interval (Ts) of the discrete time system, and the control time interval (Tc), the problem of finding a solution for the entire power system becomes stiffer, and depending on the size of the calculation interval (Ttps), it may ultimately cause numerical instability and the robustness of the results obtained through numerical analysis may also decrease.

[0096] Furthermore, if the calculation interval (Ttps) is set very small to improve accuracy in terms of the size of the input data, the size of the data from the batch processing method train running simulation results will become very large, and the large amount of data will have to be saved in the form of a text file, divided or read (input) again, and processed again for power simulation, which can reduce calculation efficiency.

[0097] To solve these problems, the stream processing method that is a feature of the present invention can be applied to reduce the time interval to the minimum time interval level (several hundred microseconds or less) that can guarantee the real-time performance of the entire power system, including the train running model. In order to apply the stream processing method to the train running model, the concept of a state machine is introduced, which can solve all of the problems of the size and accuracy of the input data mentioned above.

[0098] FIG. 8 is a flowchart showing the operation of a train running model based on a stream processing method according to an embodiment of the present invention.

[0099] First, the initial value x(0) and the input value u(t) of the system are set (S810).

[0100] In this case, x(0) is the initial value of the system and may include initial speed (0 km / h), initial position (0 km), initial train torque (0 kN), initial acceleration (0 km / h / s), initial consumed / regenerated power (0 kW), etc. u(t) represents the train power value that changes with time, and x(t) is a system state variable that changes with time and represents speed, position, acceleration, train torque, consumed power, or regenerated power. u(t) is determined by the train running calculation step (S820), and x(t) is determined by the power simulation step (S830).

[0101] Next, train running calculations are performed according to a state machine-based stream processing method (S820).

[0102] More specifically, it may include a step of calculating acceleration taking into account traction force and running resistance or braking force and running resistance (S822), a step of calculating speed and position using acceleration and unit time (time interval (Ts) of a discrete time system) (S824), and a step of performing a state machine-based stream-based train running calculation and returning a final value notch and a train power consumption value (S826).

[0103] In the step of calculating acceleration (S822), the acceleration is calculated using the tractive force, braking force, and running resistance determined according to the speed and a notch value determined by the train running state machine, as shown in Fig. 12 described below. The notch value is used to select one of the tractive force and braking force curves. When the tractive force and braking force curves are selected, the current speed is mapped to one of the two curves to convert the current train torque, and the converted torque is divided by the train mass to calculate the acceleration / deceleration.

[0104] The step of calculating the velocity and position (S824) utilizes acceleration and unit time (time interval (Ts) of a discrete time system). The unit time (time interval) is used to calculate the next calculation value (velocity, position, acceleration, etc.) based on the current calculation value (velocity, position, acceleration, etc.). For example, when calculating the next velocity from the current velocity, it can be used in the form of v=v0+a*Ts.

[0105] The notch value output in step S826 may be returned to the previous step S822, and the train power consumption value may be returned to the step in step S832.

[0106] Then, the notch value and the train power consumption value are returned, and the train running calculation is repeated again, and the train power consumption value outputted thereby is inputted to the power simulation step (S830).For reference, a notch is a controller used by an engineer to adjust the speed when a train is running, and means a notch state value (e.g., P4~, P1, N, B1~B7) when the train is running.

[0107] Next, the train power consumption output in the previous step (S820) is received as an input, and a power simulation is performed using a state space equation (S830).

[0108] More specifically, the method may include a step of dividing the train's power consumption by the voltage and inputting the result in the form of a current source into an equivalent model (S832), a step of configuring the entire power system including the current source (train load) as a state space equation and calculating a coefficient matrix (S834), and a step of deriving a discrete-time system output through the state space equation calculation and starting the power simulation again (S836).

[0109] Meanwhile, the train running calculation (S820) and the power simulation (S830) can be repeatedly performed in parallel until an interruption condition is satisfied (S840), and when the interruption condition is satisfied, the results of each calculation are saved and the process is terminated. One of the features of the present invention is that it is possible to perform a simulation without interruption, but when a request to interrupt the entire simulation is received from the user, it is determined that the interruption condition is satisfied.

[0110] Meanwhile, the train running calculation process (S820) of the stream type based on the state machine described above will be examined in more detail.

[0111] 9 to 12 are diagrams illustrating a train running calculation process based on a state machine according to an embodiment of the present invention.

[0112] First, in the train running calculation step (S826), state information is confirmed based on the speed calculated in the previous step (S824), and a notch value corresponding to the state information is output.

[0113] As shown in FIG. 9, there are four states that make up the state machine, including a stopped state, a reverse state, a sideways state, and a braking state. First, the vehicle enters the stopped state section via the entry point. This does not apply initially, but after a specific stopping time has elapsed, the state transitions to the reverse state section. The state machine then determines whether the calculated speed satisfies the speed limit reaching condition of the following formula 1, and if the speed limit reaching condition is met, the state transitions to the sideways state section.

[0114] [Formula 1] TIFF2025079323000002.tif827

[0115] In other words, it is judged whether the difference between the current driving speed (V) and the speed limit (VLIM) is smaller than the threshold, and if the condition is met, it enters the other-direction state part. In this case, the entry point is the 0 notch (N) state. However, the other-direction state part suppresses excessive notch control and, for gear control, a speed deadband (δ) is given as in Equation 2 to reduce the sensitivity of state transition.

[0116] [Formula 2] TIFF2025079323000003.tif841

[0117] In other words, the state machine includes a train's stopped state, reverse state, sideways state, and braking state, and transitions between states of the state machine depending on whether the speed has reached the speed limit, and outputs a notch value matching each state.

[0118] Figure 10 (a), (b), and (c) are diagrams of the state machine of the mascon notch in the reverse, forward, and braking states, respectively. In the reverse state, if formula 1 is satisfied, the value is 1, otherwise it is 0. When the value is 1, the state transition is in the direction of increasing speed, and when the value is 0, the state transition is in the direction of decreasing speed. At this time, the arbitrary value ε can decrease the standard in the counterclockwise direction.

[0119] As shown in (b), in the case of the other state part, if the formula 2 is satisfied, the value is 1, otherwise it is 0. When the value is 1, the speed increases, and when the value is 0, the speed decreases. At this time, the arbitrary value ε can decrease the standard in the counterclockwise direction.

[0120] As shown in (c), in the case of the braking state part, the target operation time for one section when operating at the scheduled speed and the braking point when braking with maximum torque at the current operating point are calculated first, and when the arrival conditions are met, a state transition is performed, and the entry point is set to handle the notch of B7 maximum braking force. In the stopped state part, a state transition occurs when the speed = 0, and at this time, only the stop time starts to be counted, and the current stop station and the next stop station set are moved one section at a time.

[0121] Taking the case of FIG. 11 as an example, in deriving the train operation speed profile, a speed limit is set for each part, and when the condition for satisfying the speed limit is reached as in Equation 1 and Equation 2, the state is transitioned. That is, when departing from Station 1, the train starts from a notch (P4) with maximum traction force, and when the first speed limit (speed limit n) is reached and Equation 1 or 2 is satisfied, the train transitions to the next state (P3), and the speed continues to increase, and when the maximum speed limit (speed limit 1) is reached, the state transitions to a notch (N) that has a cross train state. After that, when the speed decelerates below the speed limit, the state transitions to a notch (B1) with braking force, and the state transitions in the braking state are repeated, and the train brakes at the exact point of Station 2, which is the final stop. In this way, the train operation can be calculated only by state transitions, and the train operation can be calculated without any prior calculations such as estimating the braking point.

[0122] Meanwhile, the embodiment can be modified by objectifying the driver's pattern and reflecting the train's notch handling sensitivity element in the train operation state machine. This allows for more realistic train operation calculations to be performed, and randomness in train operation can be imparted, allowing for probabilistic optimal efficiency operation elements to be imparted to system operation in future power simulations (power system numerical calculations). In particular, this can be differentiated from the conventional batch (lump) processing train operation simulation form, which shows deterministic results through extreme operation handling of P4 notch (reverse), 0 notch (other direction), and B7 (braking), but which shows a somewhat unrealistic operation form (electric load model).

[0123] In addition, in the case of a line where the speed limit changes frequently, the driver's recognition condition of the speed limit can be reflected in the train operation state machine. In train operation calculations, the speed limit may suddenly change. For example, if a train traveling at 70 km / h with a speed limit of 80 km / h suddenly encounters a speed limit of 50 km / h, even if it accelerates suddenly, the calculation result may result in exceeding the speed limit. In order to solve this problem, the speed limit-distance table can be made into a variable in advance and reflected in the state machine diagram, and a method of transitioning to a braking state at a specific distance to reduce the speed can be applied.

[0124] FIG. 12 shows an example of an algorithm for calculating the power consumption of a train in the train running calculation process.

[0125] The train running model calculates the acceleration / deceleration and power consumption through the acceleration / deceleration calculation block and the power consumption calculation block to calculate the train power consumption. The values ​​input to the acceleration / deceleration calculation block and the power consumption calculation block are the output of the traction / brake selection block, the output of the running resistance calculation block, the output of the grade resistance lookup block, and the output of the curve resistance lookup block.

[0126] First, the tractive force lookup block or the braking force lookup block stores information on the tractive force or braking force that is previously matched and stored according to the vehicle speed value. When a speed value is input, the tractive force or braking force that matches the speed value is output. Then, the tractive force and the braking force are calculated taking into account the notch value calculated in the previous step (S826).

[0127] The running resistance calculation block inputs the speed value into a preset mathematical formula and outputs the running resistance.

[0128] In addition, the gradient resistance lookup block and the curve resistance lookup block store information on gradient resistance and curve resistance that are previously matched and stored according to the location. When the vehicle location information is input, the gradient resistance or curve resistance that matches it is output. At this time, the location information can be calculated based on the speed and travel time calculated in the previous step (S824), or the location information can be confirmed through GPS, etc.

[0129] Based on the information collected as described above, the acceleration / deceleration calculation block and the power consumption calculation block calculate and output the acceleration, deceleration, and power consumption according to a preset formula, respectively. For example, the acceleration / deceleration can be calculated by a=F / m (a is the acceleration or deceleration, F is the traction force or braking force, and m is the mass of the train). Also, the power consumption (regenerative power) can be calculated by P=Fv (P is the power consumption or regenerative power, F is the traction force or braking force, and V is the current train speed).

[0130] Through this process, when operation of a certain section is completed, the route information is updated, and when the upbound operation is completed, the upbound vehicle position calculation block is switched to the downbound vehicle position calculation block, so that the calculation is performed continuously.

[0131] FIG. 13 is a diagram showing a calculation result of a train running model according to an embodiment of the present invention.

[0132] FIG. 13(a) shows the output of the notch values ​​calculated by the state machine on a time axis.

[0133] FIG. 13(b) shows the results of vehicle speed calculation on the time axis.

[0134] FIG. 13(c) shows the vehicle position on the time axis.

[0135] FIG. 13(d) shows the train power consumption calculation results over time.

[0136] Next, we will look at the process of performing power simulation using state space equations (S830).

[0137] FIG. 14 is an illustration of an equivalent model of a railway system used in a train running model according to an embodiment of the present invention.

[0138] Figure 14(a) shows a single-formation vehicle moving load model, Figure 14(b) shows an impedance parallel configuration as a multi-formation vehicle moving load model, Figure 14(c) shows an impedance series configuration as a multi-formation vehicle moving load model, and Figure 14(d) shows the multi-formation vehicle moving load model rearranged and aligned.

[0139] The switch-free form can be derived by starting from a single-car moving load model. First, when one impedance is configured as a parallel equivalent with the same impedance, it becomes a form multiplied by N impedance values. Then, since the car load (current source) is also connected at the same node, it can be configured as a parallel current source. When this is rearranged and aligned, it can be changed to a form that is easy to apply to the train diagram, as shown in (d).

[0140] FIG. 15 shows the process of analyzing an equivalent model of a railway system used in a train running model according to an embodiment of the present invention.

[0141] In the multi-vehicle movement load model shown in (d) of Figure 14, the model can be divided into each element. The magnitude of each resistance is the same in each drawing, but the change may be different because the operation intervals of each train are different.

[0142] Figure 15(a) shows a parallel configuration when railway system model decomposition is applied, Figure 15(b) shows a series configuration when railway vehicle model decomposition is applied, and Figure 15(c) shows a system decomposition method using the model reduction method.

[0143] Such an equivalent model can be expressed as a state space equation and solved.

[0144] For example, matrices and vectors of the following form may be derived:

[0145] TIFF2025079323000004.tif2064

[0146] In this case, the number of elements required to configure the state space matrix of the existing DC railway system model as a single group is assumed to be, for example, 37 inputs, 74 state values, 94 outputs, and 94 switches. For real-time calculation, the scale that the simulator must pre-calculate and secure cache memory is 274 times, which is impossible to store in memory, and even if the number of switch contacts is reduced, it is impossible to perform simulation with a time sampling of about 50 μs.

[0147] TIFF2025079323000005.tif2081

[0148] However, when the method of the present invention is used, the capacity stored in the cache memory before real-time calculation is 393.626 Mb. The total calculation groups are divided into 67 groups, most of which are groups consisting of only inputs and outputs, and the remaining group is three substations, each of which is composed of 28 states, 35 inputs, 20 outputs, and 12 switches. For reference, these 12 switches are all equivalent to 12 pulse diodes, and the diodes are classified as switches and included in the calculation. However, in the end, the scale of calculations to be pre-calculated before real-time simulation is significantly reduced to 212*3 times the sum of the number of elements of the state space matrix, rather than 236 times. Therefore, during real-time simulation, the calculations consumed for the inputs and outputs of the system model stored in the cache memory within the same time interval are reduced, ensuring real-time performance. However, the number of diodes or switches in one substation may vary depending on the type of the substation. For example, in the case of a thyristor converter of a bidirectional converter, 24 thyristors are included in one substation.

[0149] 2. Configuration of Converter Station Simulation Program

[0150] The DC / DC converter in the converter station model is composed of switching elements, inductors, capacitors, etc., and its configuration is realized using the element model provided by the real-time simulator. The DC / DC converter that supplies the power required for train operation in the converter station can be configured as follows.

[0151] The configuration of DC / DC converters can be classified according to whether the distribution system is a two-circuit or three-circuit system. When the distribution system is a two-circuit system, it is configured with + and - poles. For example, if the distribution system voltage is linked at ±20KV, the input of the DC / DC converter of the converter station can be configured with a magnitude of 40KV. Also, the output is a railway operating voltage of 3000V / 1500V / 750V. In this case, assuming that the unit capacity of one converter station is 2MW, it may be necessary to add two or three converter stations in parallel, taking into account the maximum capacity depending on the interval (schedule) and capacity of the trains to be operated. In this way, when converter stations are added in parallel, balancing control may be required within the converter stations.

[0152] When a power distribution system has three lines, each line is composed of positive and negative poles and a neutral line, and when the power distribution system voltage is connected at ±20KV as an example, the DC / DC converters in the converter station can be composed of one 20KV converter whose input is composed of a positive pole and a neutral line, and another 20KV converter whose input is composed of a negative pole and a neutral line. If the converter has the same topology as the two-line case, two 1MW DC / DC converters are required to meet the unit capacity of one converter station of 2MW.

[0153] Also, depending on the intervals (schedule) and capacity of the trains in operation, it may be necessary to add two or three converter stations in parallel, taking into account the maximum capacity. Even if converter stations are added in parallel, the overall balancing can be maintained by each converter performing its own balancing control. This balancing control can perform a control logic in the form of balancing through the adjustment of the amount of power (P) by selecting a reference voltage on the series configuration side and performing PI control that eliminates the error between this reference voltage and the actual voltage measured. It is preferable that such a DC / DC converter topology is designed taking into account the following railway characteristics.

[0154] - Considering a wide range of load fluctuations from light to medium loads (vehicle configuration, operation intervals / speed, acceleration / deceleration, etc.) (maintaining high efficiency over a wide load range)

[0155] - Considering large moving load (approximately 1MW per M Car)

[0156] - Regenerative energy generation (taking into account bidirectional power flow)

[0157] - By applying the insulated type, it can be separated from the Korean power grid

[0158] - Balancing control ensures control stability

[0159] FIG. 16 shows a series resonant DAB converter applied to a converter station model according to one embodiment of the present invention, and FIG. 17 shows the ISOP connection state of the series resonant DAB converter applied to a converter station model according to one embodiment of the present invention.

[0160] First, referring to FIG. 16, the structure of a 2-series HB-based series resonant type DAB converter can be seen as a DC / DC converter.

[0161] The series resonant DAB converter 400 includes an input circuit 410, an output circuit 430, a transformer 440, and a resonant circuit 450. In this case, the series resonant DAB converter 400 includes not only elements in the form of an actual circuit, but also all of those embodied in the form of software constituting a DC / DC converter in a converter station model.

[0162] The input circuit (410) includes a power supply, a first capacitor (415) and a second capacitor (416) connected in series to the power supply, and first to fourth switching elements (411, 412, 413, 414) connected in series to the power supply in a half-bridge configuration. The first capacitor (415) is connected in parallel to the first switching element (410) and the second switching element (412), and the second capacitor (416) is connected in parallel to the third switching element (414) and the fourth switching element (416). A connection node (N3) to which the first capacitor (415) and the second capacitor (146) are connected, and a connection node (N4) to which the second switching element (412) and the third switching element (413) are connected are connected to each other, and a neutral point current (Inp) flows between the connection node (N3) and the connection node (N4).

[0163] A resonant circuit 450 and a transformer 440 are coupled between the input circuit 410 and the output circuit 430. The resonant circuit 450 is coupled between a connection node N1 of the first switching element 411 and the second switching element 412 and a connection node N2 of the third switching element 413 and the fourth switching element 414, and may include a capacitor Cr and an inductor Lr connected in series with each other.

[0164] Moreover, the transformer (440) has one terminal of the primary side connected to the output end (terminal of the inductor (Lr)) of the resonant circuit (450), and the other terminal of the primary side connected to the connection node (N2).

[0165] The output circuit 430 includes a first switching element 431, a second switching element 432, a third switching element 433, and a fourth switching element 434 connected in a full bridge configuration. In this case, the output circuit 430 is connected to the secondary side of the transformer 440, one terminal of the secondary side is connected to a connection node N5 between the first switching element 431 and the second switching element 432, and the other terminal of the secondary side is connected to a connection node N6 between the third switching element 433 and the fourth switching element 434.

[0166] In this way, the series resonant DAB converter according to the present invention differs from the converter in Fig. 3 in that the input side is configured in a two-series configuration based on a half-bridge. Therefore, the switching withstand voltage that the unit switches must withstand can be half the input side power supply voltage Vdc. Therefore, it can be seen that the number of elements required on the input side under the same withstand voltage conditions is half that of a full-bridge.

[0167] Also, as shown in FIG. 17, the series resonant DAB converter can be extended to an ISOP structure to apply it to MVDC. The input voltage for MVDC reaches several tens of kV, so if this is configured based on a conventional full bridge, the number of active / passive elements increases significantly, and additional control requirements such as current balancing between the increased submodules increase. However, if an ISOP is configured based on the half bridge-based series resonant DAB converter proposed in the present invention, the number of active / passive elements is reduced by half, and the controller configuration for current balancing is also reduced by half and simplified. That is, in the case of FIG. 4, the switching withstand voltage of the unit switch is Vdc as a conventional two-level FB structure circuit, while the method proposed in FIG. 17 has a switching withstand voltage of the unit switch based on HB, which is half, so the number of passive elements can be reduced by half under the same switching withstand voltage conditions.

[0168] FIG. 18 is a diagram for explaining the operation of the series resonant DAB converter according to one embodiment of the present invention.

[0169] Specifically, it shows the output leg voltage and neutral point (NP) current depending on the switching state of the input circuit. The first switching element (QA1, 411) and the second switching element (QA2, 412) operate complementarily, and the third switching element (QA3, 413) and the fourth switching element (QA4, 414) also operate complementarily. The primary leg voltage (VA), which represents the voltage between the connection node (N1) and the connection node (N2), is output in three stages: 0, E, and 2E. Here, E represents the unit voltage of the capacitors (Cdc1, Cdc2).

[0170] It can also be seen that the neutral point current (Inp) between the connection node (N3) and the connection node (N4) is ILr or -ILr depending on the switching state of the circuit under the condition of VA = E. Here, it can be seen that the neutral point current is related to the direction of the resonant current.

[0171] The converter (400) of the present invention also has two input capacitors (415, 416) connected in series, so it is necessary to control the voltage of the capacitors carefully to prevent voltage deviation. For this reason, the present invention applies a new switching sequence, and by using this, a separate controller is not required.

[0172] FIG. 19 shows primary / secondary leg voltage waveforms of a series resonant DAB converter according to an embodiment of the present invention.

[0173] As mentioned above, the primary leg voltage (VA) indicates the voltage between the connection node (N1) and the connection node (N2), and the secondary leg voltage (VB) indicates the voltage between the connection node (N5) and the connection node (N6). Since the E level is essential to control the voltage balancing between the capacitors, the voltage is designed to have an overall stepped voltage shape of 0->E->2E. For reference, this type of control method can also be useful for ZVS switching of the secondary switch.

[0174] The duration of the voltage level is π(1-k 1), where the primary leg voltage (VA) and secondary leg voltage (VB) have a phase difference of only φ. Here, k1 is a modulation index that ranges from 0 to 1, but in the present invention, its value is fixed (for example, at 0.9) and the output voltage is adjusted by the phase difference (φ). The output power Po and output voltage Vo are all smoothly adjusted in proportion to the phase difference sinφ.

[0175] The following formulas 3 to 5 show the relationship between the output power (Po) and the output voltage (Vo) of the converter according to the present invention. X represents the equivalent impedance of the resonant circuit (450, Lr-Cr) at the switching frequency ωsw. Here, ωr corresponds to the resonant frequency of the resonant circuit (450), and R represents the output resistance.

[0176] [Formula 3] TIFF2025079323000006.tif1038

[0177] [Formula 4] TIFF2025079323000007.tif1038

[0178] [Formula 5] TIFF2025079323000008.tif1931

[0179] We now turn to the switching sequence for driving the series resonant DAB converter according to the invention.

[0180] FIG. 20 shows a case where a switching sequence of a general phase transition method is applied to the present invention.

[0181] A typical phase transition switching technique adjusts the gates to adjust the timing of turn-on / turn-off of a 50% duty signal in the order of A1→A4→A2→A3→A1→... as shown in Figure 20. With this phase transition method, as shown in Figure 20, in the switching pairs (2E,E) and (E,0) that make up the E level, Inp all become positive, Cdc1 continues to charge and Cdc2 continues to discharge, and there is a problem that voltage balancing is not possible. This is because not all switching forms that express the E level are utilized. In order to solve this problem, the present invention proposes a new switching sequence by applying the voltage magnitude modulation method and clamp mode.

[0182] 21 and 22 show switching sequences of a pulse magnitude modulation scheme for driving a series resonant DAB converter according to the present invention.

[0183] For reference, in the following drawings, Gate A, Carrier A, Vampl_a, Vcmd_a, etc. refer to signals on the primary side or input circuit (410) side of the transformer (440), and Gate B, Carrier B, Vampl_b, Vcmd_b, etc. refer to signals on the secondary side or output circuit (430) side of the transformer (440).

[0184] The first switching sequence applied to the first switching element (411, Gate A1) periodically repeats a first pulse having a pulse width and a first level amplitude during a reference time (T / 2), a second pulse having a pulse width and a second level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, a third pulse having a pulse width and the first level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a second level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time.

[0185] Similarly, the second switching sequence applied to the third switching element (413, Gate A3) periodically repeats a first pulse having a pulse width and a second level amplitude during a reference time (T / 2), a second pulse having a pulse width and a first level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time, a third pulse having a pulse width and a second level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a first level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time. At this time, the first level may be a high level, and the second level may be a low level that is distinguished from the first level.

[0186] That is, the first switching element (411, GateA1) is turned on / off in the order of T / 2->T / 2-ΔT->T / 2->T / 2+ΔT->T / 2->..., and the third switching element (413, GateA3) is turned on / off in the order of T / 2->T / 2+ΔT->T / 2->T / 2->T / 2->.... This special switching pattern utilizes both the positive and negative polarities of the neutral point current, naturally achieving the purpose of voltage balancing of the input capacitor. Meanwhile, the second switching element (412, GateA2) and the fourth switching element (414, GateA4) have complementary characteristics, and thus the switching sequences opposite to those of the first switching element (411, GateA1) and the third switching element (413, GateA3), respectively, are determined.

[0187] With this configuration, as shown in FIG. 22, in the (E,0) and (2E,E) switching pairs that make up the E level, the neutral point current (Inp) has negative and positive sections, Cdc1 and Cdc2 alternately charge and discharge, and it can be seen that the voltages of Cdc1 (Vdc1) and Cdc2 (Vdc2) rise and fall relative to each other, thereby enabling voltage balancing between the capacitors to be performed.

[0188] As a result, during one period of the first switching sequence and the second switching sequence, the first neutral point current (Inp) includes both a section having a negative value and a section having a positive value.

[0189] In this case, the pulse widths of the first pulse of the first switching sequence and the first pulse of the second switching sequence are the same, but the first pulse of the second switching sequence is arranged to be faster than the first pulse of the first switching sequence by a predetermined time (ΔT), i.e., the rising edge of the first pulse of the first switching sequence is arranged to be slower than the falling edge of the first pulse of the second switching sequence by a predetermined time (ΔT).

[0190] In addition, the pulse width of the second pulse of the first switching sequence is set to (T / 2-ΔT), and the pulse width of the second pulse of the second switching sequence is set to (T / 2+ΔT), and the rising edge of the second pulse of the second switching sequence is arranged to be earlier than the falling edge of the first pulse of the first switching sequence by the predetermined time (ΔT), and the falling edge of the second pulse of the second switching sequence is arranged to be later than the rising edge of the second pulse of the first switching sequence by the predetermined time (ΔT).

[0191] Also, the pulse widths of the third pulse of the first switching sequence and the third pulse of the second switching sequence are the same, but are arranged so that the rising edge of the third pulse of the first switching sequence is earlier than the falling edge of the third pulse of the second switching sequence by a predetermined time (ΔT). At the initial start point, the second switching sequence is arranged to be earlier by the predetermined time (ΔT), but during the operation time of the second pulse, the second pulse width of the second switching sequence is set to be longer than twice the predetermined time (2ΔT), so that the third pulse of the second switching sequence is delayed by the predetermined time (ΔT).

[0192] In addition, the pulse width of the fourth pulse of the first switching sequence is set to (T / 2+ΔT), the pulse width of the fourth pulse of the second switching sequence is set to (T / 2-ΔT), and they are arranged so that the falling edge of the fourth pulse of the first switching sequence is earlier than the rising edge of the fourth pulse of the second switching sequence by the predetermined time (ΔT), and the rising edge of the fourth pulse of the first switching sequence is later than the falling edge of the fourth pulse of the second switching sequence by the predetermined time (ΔT).

[0193] With this configuration, a negative neutral current (Inp) flows only during the time interval (ΔT) between the falling edge of the first pulse of the second switching sequence and the rising edge of the first pulse of the first switching sequence, and a negative neutral current (Inp) flows only during the time interval (ΔT) between the rising edge of the second pulse of the second switching sequence and the falling edge of the second pulse of the first switching sequence.

[0194] In addition, a positive neutral current (Inp) flows only during the time interval (ΔT) between the rising edge of the third pulse of the first switching sequence and the falling edge of the third pulse of the second switching sequence, and a positive neutral current (Inp) flows only during the time interval (ΔT) between the falling edge of the fourth pulse of the first switching sequence and the rising edge of the fourth pulse of the second switching sequence.

[0195] On the other hand, Fig. 21 shows the switching pattern design of the proposed pulse magnitude modulation method. Vcmd_A represents a command voltage whose amplitude alternates between ±Vampl_a every half period, and the clamping mode (CM) is operated at 1 in the first period, and CM is operated at -1 in the next period.

[0196] A down-counting triangular wave is used as the carrier wave, and command values ​​(Vcmd_a1 and Vcmd_a3) for the first switching element (411, QA1) and the third switching element (413, QA3) are set as follows according to CM.

[0197] When CM=1, Vcmd_a1 has a value of 0.5Vcmd_a and Vcmd_a3 has a value of -0.5Vcmd_a. The offset voltage (Voffset) is set to Vdc_ref / 4-max(Vcmd_a1, Vcmd_a3), where max(a, b) is a function that outputs the larger of a and b.

[0198] Conversely, when CM=-1, the polarity of Vcmd_a1 and Vcmd_a3 is set to the opposite of when CM=1, and the offset voltage (Voffset) is calculated in the same way. After that, the offset voltage and Vdc_ref / 4 are added to the original command values ​​Vcmd_a1 and Vcmd_a3 to calculate the PWM command value, and finally, this is divided by Vdc_ref / 2 to calculate the final normalized PWM command value that can be used to plot N_max and compare it with the triangular carrier wave.

[0199] If the PWM command value is calculated according to CM as described above, the special switching sequence shown in Figure 21 can be expressed, where the first switching element (GateA1) is turned on / off in the order of T / 2->T / 2-ΔT->T / 2->T / 2+ΔT->T / 2->..., and the third switching element (GateA3) switches in the order of T / 2->T / 2+ΔT->T / 2->T / 2->T / 2->.... Such a special switching pattern utilizes both the positive and negative polarities of the neutral point current, naturally achieving the purpose of voltage balancing of the input capacitor.

[0200] FIG. 22 shows the main waveforms of the simulation results of the series resonant DAB converter. PWM_CMD_a1 determines the On / Off of GateA1 by comparing with the primary side carrier, and PWM_CMD_a3 determines the On / Off of GateA3 by comparing with the primary side carrier. Meanwhile, the second switching element (412, GateA2) and the fourth switching element (414, GateA4) are determined to switch in the opposite direction to the first switching element (411, GateA1) and the third switching element (413, GateA3) by their complementary characteristics. In FIG. 20, which uses a general phase transition method, only the positive value of the neutral point current (Inp) is used, but here, all positive and negative values ​​of the neutral point current (Inp) can be used, so it can be seen that the voltage deviation of the input capacitor is naturally eliminated. It can be seen that both the positive and negative values ​​of the neutral point current (Inp) are used in either condition of CM=1 or CM=-1, and the voltage deviation of the capacitor is eliminated.

[0201] FIG. 23 shows the relationship between the carrier and the PWM command value in the method for driving the series resonant DAB converter according to one embodiment of the present invention.

[0202] In order to output a symmetric leg waveform, the initial value and count direction of the carrier are reversed according to CM (FIG. 23(a)). Then, during the section where the PWM command value (PWM-CMD) is greater than the carrier, a signal (GateA or GateB) for turning on the corresponding switch is output, as in FIGS. 21 and 22, and during the remaining section, a signal for turning off the corresponding switch is output. In the case of FIG. 23(a), during the first pulse section of the carrier, PWM_CMD_a1 (dotted line signal) is always greater than the carrier, so a signal (GateA1) for turning on the first switching element (411) is output, and during the section where PWM_CMD_a2 (solid line signal) is temporarily greater than the carrier, a signal (GateA3) for turning on the third switching element (413) is output.

[0203] On the other hand, a method of inversely applying the relationship between the command value and the carrier according to CM while leaving the carrier as it is (FIG. 23(b)) can also be implemented, and this method is more suitable for the method utilizing the primary / secondary phase difference. That is, when CM=-1, during the period in which the PWM command value (PWM-CMD) is smaller than the carrier, a signal (GateA or GateB) that turns on the corresponding switch is output, and during the remaining period, a signal that turns off the corresponding switch is output.

[0204] When calculating the offset voltage (Voffset), when CM = -1, Voffset should normally be = Vdc_ref / 4 - min(Vcmd_a1, Vcmd_a3). However, if you choose the method in Figure 23(b), you can expect the same effect by setting the max value instead of the min value when CM = -1 and reversing the polarity of Vcmd_a1 and Vcmd_a3.

[0205] FIG. 24 illustrates a process of selecting a command mode (CM) in a method of driving a series resonant DAB converter according to an embodiment of the present invention.

[0206] The voltages of the input capacitors (Vdc1, Vdc2) are input, the flow of power (Power) (positive: direction of power flow from source to load, negative: direction of power flow from load to source) is determined, and the command mode (CM) is determined based on the magnitude relationship between the voltages of the first capacitor (Vdc1) and the second capacitor (Vdc2). For example, if power flows from the source to the load and the voltage of the first capacitor (Vdc1) is greater than the voltage of the second capacitor (Vdc2), CM = 1, and if the voltage of the first capacitor (Vdc1) is less than the voltage of the second capacitor (Vdc2), CM = -1. Also, if power flows from the load to the source and the voltage of the first capacitor (Vdc1) is greater than the voltage of the second capacitor (Vdc2), CM = -1, and if the voltage of the first capacitor (Vdc1) is less than the voltage of the second capacitor (Vdc2), CM = 1.

[0207] 25 to 27 are block diagrams of a control logic for outputting a control signal of a series resonant DAB converter according to an embodiment of the present invention.

[0208] The illustrated control logic may be embodied in the converter controller (300) in the form of hardware.

[0209] First, FIG. 25 shows a control logic for determining the phase difference between the primary and secondary sides of a transformer, or between the input circuit and the output circuit.

[0210] The phase difference is determined by integrating the difference between the output (Vo) and the initial value (Vo*) of the series resonant DAB converter through a PI controller, and upper and lower limits are set. Through this process, the primary side carrier (Carrier_A) and secondary side carrier (Carrier_B) are output, respectively.

[0211] Next, FIG. 26 shows a control logic for outputting a switching sequence on the primary side or the input circuit side.

[0212] As described in the explanation of FIG. 21, Vcmd_A indicates a command voltage whose amplitude alternates between ±Vampl_a every half period, and the offset voltage (Voffset) is determined according to the clamp mode.

[0213] When CM=1, Vcmd_a1 has a value of 0.5*Vcmd_A, and Vcmd_a3 has a value of -0.5*Vcmd_A. The offset voltage is calculated as 0.25*Vdc-max(Vcmd_a1, Vcmd_a3) based on CM_a, Vcmd_a1, and Vcmd_a3. These offset voltages are added equally to the original command values ​​Vcmd_a1 and Vcmd_a3, respectively, and calculated as VCMD_a1 and VCMD_a3. Here, max(a,b) is a function that outputs the larger of a and b. VCMD_a1 and VCMD_a3 are normalized by dividing them by 0.5*Vdc, and the value multiplied by N_max is output as the PWM command voltage (PWM_CMD_a1, PWM_CMD_a3).

[0214] Conversely, when CM=-1, the polarity of Vcmd_a1 and Vcmd_a3 is set to the opposite of when CM=1 (Vcmd_a1=-0.5*Vcmd_A, Vcmd_a3=0.5*Vcmd_A), and the offset voltage is calculated in the same way. After that, the offset voltage is added equally to the original command values ​​Vcmd_a1 and Vcmd_a3, respectively, to calculate VCMD_a1 and VCMD_a3. Finally, it is normalized by dividing by 0.5Vdc, and then multiplied by N_max to calculate the final PWM command values ​​(PWM_CMD_a1, PWM_CMD_a3) that can be compared to the triangular carrier wave.

[0215] The dead time block prevents the first switching element (411) and the second switching element (412) from being turned on at the same time, allowing them to operate in a complementary manner, and similarly prevents the third switching element (413) and the fourth switching element (414) from being turned on at the same time, allowing them to operate in a complementary manner.

[0216] Next, FIG. 27 shows a control logic for outputting a switching sequence on the secondary side or the output circuit side.

[0217] Looking specifically at the operation of the secondary side, Vcmd_B indicates a command voltage whose amplitude alternates between ±Vampl_b every half cycle, and the offset voltage (Voffset) is determined by the clamp mode.

[0218] When CM=1, Vcmd_b1 has a value of 0.5Vcmd_B and Vcmd_b3 has a value of -0.5Vcmd_B. The offset voltage is calculated based on CM_b, Vcmd_b1, and Vcmd_b3 as 0.5*Vo-max(Vcmd_b1, Vcmd_b3). These offset voltages are added equally to the original command values ​​Vcmd_b1 and Vcmd_b3, respectively, to calculate VCMD_b1 and VCMD_b3. VCMD_b1 and VCMD_b3 are normalized by dividing them by Vo, and then multiplied by N_max to be output as the PWM command voltages (PWM_CMD_b1, PWM_CMD_b3).

[0219] Conversely, when CM=-1, the polarity of Vcmd_b1 and Vcmd_b3 is set to the opposite of when CM=1 (Vcmd_b1=-0.5*Vcmd_B, Vcmd_b3=0.5*Vcmd_B), and the offset voltage is calculated in the same way. After that, the offset voltage is added equally to the original command values ​​Vcmd_b1 and Vcmd_b3, respectively, to calculate VCMD_b1 and VCMD_b3. Finally, it is normalized by dividing by Vo, and then multiplied by N_max to calculate the final PWM command values ​​(PWM_CMD_b1, PWM_CMD_b3) that can be compared to the triangular carrier wave.

[0220] The dead time block prevents the first switching element (431) and the second switching element (432) from being turned on at the same time, allowing them to operate in a complementary manner, and similarly prevents the third switching element (433) and the fourth switching element (434) from being turned on at the same time, allowing them to operate in a complementary manner.

[0221] An embodiment of the present invention may also be embodied in the form of a recording medium including computer executable commands, such as a program module executed by a computer. A computer readable medium may be any available medium accessible by a computer, including both volatile and nonvolatile media, removable and non-removable media. A computer readable medium may also include computer storage media. A computer storage medium includes both volatile and nonvolatile, removable and non-removable media embodied in any method or technology for storing information, such as computer readable commands, data structures, program modules, or other data.

[0222] Although the method and system of the present invention have been described with reference to specific embodiments, some or all of its components or operations may be implemented using a computer system having a general-purpose hardware architecture.

[0223] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described as a single type can be implemented in a distributed manner, and similarly, each component described as a distributed type can be implemented in a combined form.

[0224] The scope of the present invention is indicated by the claims set forth below rather than by the above detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention. [Explanation of symbols]

[0225] 100: Computing equipment 110: Processor 120:Memory 130: Communication module 140: Database

Claims

1. In a simulation system for a railway system on a medium-voltage direct current (MVDC) distribution network, a computing device storing a simulation program including a converter station model simulating a converter station included in the MVDC power distribution network and a train running model simulating a running state of a train operated by receiving power from the converter station; A converter controller that controls a DC / DC converter included in the converter station model; and The HILS (Hardware In the Loop Simulation) device performs a simulation based on the converter station model, the train running model, and the converter controller. A simulation system for a railway system, wherein the converter station model and the train running model are executed by software in the HILS device, and the converter controller is connected to the HILS device and driven to control the converter station model.

2. In claim 1, The described simulation program uses the train running model to perform a stream processing train running simulation, The train running model is configured to perform power simulation in the following manner: calculate the acceleration of the train based on the traction force and running resistance or the braking force and running resistance of the train, calculate the speed and position using the calculated acceleration and a time interval of a discrete time system, perform a state machine-based stream-type train running calculation using the speed and position, and output a notch value and train power consumption; convert the train power consumption into a current source and input it to an equivalent model, calculate a coefficient matrix from a state space equation representing the equivalent model, and output a discrete time system through the calculation of the state space equation.

3. In claim 2, The train running model described is A simulation system for a railway system, which inputs the speed into a state machine including the train's stopped state, reversing state, other moving state, and braking state, transitions the state of the state machine based on whether the speed has reached the speed limit, and outputs a notch value that matches each state.

4. In claim 2, The train running model described is outputting a traction force or a braking force corresponding to the speed, and outputting a running resistance corresponding to the speed; A railway system simulation system which calculates the acceleration and power consumption of the train based on the notch value output by the state machine according to the speed, the traction force or braking force, the running resistance, and the gradient resistance or curve resistance corresponding to the position of the train.

5. In claim 1, The converter station model described uses a series resonant DAB converter as a DC / DC converter, The series resonant DAB converter comprises: an input circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected according to a full bridge configuration; A railway system simulation system including a resonant circuit and a transformer connected between the input circuit and the output circuit.

6. In claim 1, The converter station model described uses multiple series resonant DAB converters connected in an ISOP (Input-Series-Output-Parallel) structure as DC / DC converters. Each series resonant DAB converter has the following features: The series resonant DAB converter comprises: an input circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected according to a full bridge configuration; A railway system simulation system including a resonant circuit and a transformer connected between the input circuit and the output circuit.

7. In claim 5 or claim 6, The resonant circuit and the transformer described are coupled between a connection node of the first switching element and the second switching element of the input circuit and a connection node of the third switching element and the fourth switching element, the resonant circuit includes a capacitor and an inductor connected in series with each other; a primary side terminal of the transformer is connected to the resonant circuit, and a primary side terminal of the transformer is connected to a connection node of a third switching element and a fourth switching element of the input circuit; A simulation system for a railway system, wherein one terminal of the secondary side of the transformer is connected to a connection node of a first switching element and a second switching element of the output circuit, and the other terminal of the secondary side is connected to a connection node of a third switching element and a fourth switching element of the output circuit.

8. In claim 5 or claim 6, The converter controller includes a control logic for applying a first switching sequence to the first switching element and the second switching element of the input circuit in a complementary manner and applying a second switching sequence to the third switching element and the fourth switching element in a complementary manner, the first switching sequence is a sequence in which a first pulse having a pulse width and a first level amplitude during a reference time (T / 2), a second pulse having a pulse width and a second level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, a third pulse having a pulse width and the first level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a second level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time are periodically repeated; The second switching sequence is a sequence in which a first pulse having a pulse width and a second level amplitude during a reference time (T / 2), a second pulse having a pulse width and a first level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time, a third pulse having a pulse width and a second level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a first level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, are periodically repeated; A simulation system for a railway system, wherein the first level is a high level and the second level is a low level as distinguished from the first level.

9. Simulation method for railway systems on MVDC (Medium-Voltage Direct Current) distribution networks. (a) executing, in a software manner, a simulation program including a converter station model simulating a converter station included in the MVDC power distribution network and a train running model simulating a running state of a train operated by receiving power from the converter station, in a Hardware In the Loop Simulation (HILS) device; (b) A method for simulating a railway system, comprising the step of connecting a converter controller that controls a DC / DC converter included in the converter station model to the HILS device and driving the converter controller to control the converter station model.

10. In claim 9, The step (a) described includes a step of performing a stream processing train running simulation using the train running model, The step of performing the train running simulation includes: (a-1) calculating the acceleration of a train based on the tractive force and running resistance or the braking force and running resistance of the train; (a-2) calculating velocity and position using the calculated acceleration and the time interval of the discrete-time system; (a-3) performing a state machine-based stream-based train running calculation using the speed and position, and outputting a notch value and a train power consumption; (a-4) converting the train power consumption into a current source and inputting the current source into an equivalent model; (a-5) calculating a coefficient matrix from a state space equation representing the equivalent model; (a-6) performing a power simulation in a manner of outputting a discrete-time system through calculation of the state space equations.

11. In claim 10, The step (a-3) described is A simulation method for a railway system, comprising: inputting the speed into a state machine including a train's stopped state, reverse state, other running state, and braking state; transitioning the state of the state machine based on whether the speed has reached the speed limit; and outputting a notch value that matches each state.

12. In claim 10, The step (a-3) described is outputting a traction force or a braking force corresponding to the speed, and outputting a running resistance corresponding to the speed; A simulation method for a railway system, which calculates the acceleration and power consumption of the train based on the notch value output by a state machine according to the speed, the traction force or braking force, the running resistance, and the gradient resistance or curve resistance corresponding to the position of the train.

13. In claim 9, The step (a) described above is to execute a simulation program in a software manner using the converter station model in a HILS device; The converter station model uses a series resonant type DAB converter as a DC / DC converter, The series resonant DAB converter comprises: an input circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected according to a full bridge configuration; A method for simulating a railway system, comprising: a resonant circuit and a transformer connected between the input circuit and the output circuit.

14. In claim 9, The step (a) described above is to execute a simulation program in a software manner using the converter station model in a HILS device; The converter station model uses multiple series resonant type DAB converters connected in an ISOP (Input-Series-Output-Parallel) structure as DC / DC converters, Each series resonant DAB converter has the following features: The series resonant DAB converter comprises: an input circuit including a first switching element, a second switching element, a third switching element, and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected according to a full bridge configuration; A method for simulating a railway system, comprising: a resonant circuit and a transformer connected between the input circuit and the output circuit.

15. In claim 13 or claim 14, The step (a) includes connecting one terminal of the transformer to a connection node of the first switching element and the second switching element, The other terminal of the transformer is connected to the connection node of the third switching element and the fourth switching element described above. a resonant circuit connected between a connection node of the first switching element and the second switching element and one terminal of the transformer;

16. In claim 13 or claim 14, The step (b) of the description is A control method is performed in which a first switching sequence is complementarily applied to the first switching element and the second switching element through the converter controller, and a second switching sequence is complementarily applied to the third switching element and the fourth switching element through the converter controller. the first switching sequence is a sequence in which a first pulse having a pulse width and a first level amplitude during a reference time (T / 2), a second pulse having a pulse width and a second level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, a third pulse having a pulse width and the first level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a second level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time are periodically repeated; The second switching sequence is a sequence in which a first pulse having a pulse width and a second level amplitude during a reference time (T / 2), a second pulse having a pulse width and a first level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time, a third pulse having a pulse width and a second level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a first level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, are periodically repeated; A method for simulating a railway system, wherein the first level is a high level and the second level is a low level as distinguished from the first level.

17. In a railway system simulation device, A memory in which a simulation program including a train running model that simulates the running state of a train is stored; and a processor for executing the simulation program; The simulation program performs a train running simulation using a stream processing method by using the train running model, The train running model calculates the acceleration of the train based on the traction force and running resistance or the braking force and running resistance of the train, calculates the speed and position using the calculated acceleration and a time interval of a discrete time system, performs a state machine-based stream-type train running calculation using the speed and position to output a notch value and train power consumption, converts the train power consumption into a current source and inputs it to an equivalent model, calculates a coefficient matrix from a state space equation representing the equivalent model, and performs a power simulation by calculating the state space equation to output a discrete time system.

18. In claim 17, The train running model described is A railway system simulation device that inputs the speed into a state machine that includes the train's stopped state, reversing state, other moving state, and braking state, transitions the state of the state machine based on whether the speed has reached the speed limit, and outputs a notch value that matches each state.

19. In claim 17, The train running model described is outputting a traction force or a braking force corresponding to the speed, and outputting a running resistance corresponding to the speed; A railway system simulation device that calculates the acceleration and power consumption of the train based on the notch value output by a state machine according to the speed, the traction force or braking force, the running resistance, and the gradient resistance or curve resistance corresponding to the position of the train.

20. A train running simulation method using a stream processing method, which uses a railway system simulation device, (a) calculating the acceleration of a train based on the tractive effort and running resistance or the braking effort and running resistance of the train; (b) calculating velocity and position using the calculated acceleration and the time intervals of the discrete time system; (c) performing a state machine based stream-based train running calculation using the speed and position to output a notch value and a train power consumption; (d) converting the power consumption of the train into a current source and inputting the current source into an equivalent model; (e) calculating a coefficient matrix from the state space equations representing the equivalent model; and (f) performing a power simulation in a manner of outputting a discrete-time system through calculation of the state space equations.

21. In claim 20, The step (c) of the description is A train running simulation method, comprising: inputting the speed into a state machine including a train's stopped state, reverse state, other running state, and braking state; transitioning the state of the state machine based on whether the speed has reached the speed limit; and outputting a notch value that matches each state.

22. In claim 20, The step (c) of the description is outputting a traction force or a braking force corresponding to the speed, and outputting a running resistance corresponding to the speed; A train running simulation method for calculating the acceleration and power consumption of the train based on the notch value output by a state machine according to the speed, the traction force or braking force, the running resistance, and the gradient resistance or curve resistance corresponding to the position of the train.

23. A computer-readable recording medium having recorded thereon a computer program for executing the train running simulation method according to any one of claims 20 to 22.

24. In a series resonant type DAB converter, an input circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected according to a full bridge configuration; A series resonant DAB converter including a resonant circuit and a transformer connected between the input circuit and the output circuit.

25. In claim 24, The resonant circuit and the transformer described are coupled between a connection node of the first switching element and the second switching element of the input circuit and a connection node of the third switching element and the fourth switching element, the resonant circuit includes a capacitor and an inductor connected in series with each other; one terminal of a primary side of the transformer is connected to the resonant circuit, and the other terminal of the primary side is connected to a connection node of a third switching element and a fourth switching element of the input circuit; A series resonant DAB converter, in which one terminal of the secondary side of the transformer is connected to a connection node of a first switching element and a second switching element of the output circuit, and the other terminal of the secondary side is connected to a connection node of a third switching element and a fourth switching element of the output circuit.

26. In claim 24, The input circuit is driven by a control logic that applies a first switching sequence to the first switching element and the second switching element in a complementary manner and applies a second switching sequence to the third switching element and the fourth switching element in a complementary manner. the first switching sequence is a sequence in which a first pulse having a pulse width and a first level amplitude during a reference time (T / 2), a second pulse having a pulse width and a second level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, a third pulse having a pulse width and the first level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a second level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time are periodically repeated; The second switching sequence is a sequence in which a first pulse having a pulse width and a second level amplitude during a reference time (T / 2), a second pulse having a pulse width and a first level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time, a third pulse having a pulse width and a second level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a first level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, are periodically repeated; A series resonant DAB converter, wherein the first level is a high level and the second level is a low level as distinguished from the first level.

27. A DC / DC converter in which a plurality of series resonant type DAB converters according to any one of claims 24 to 26 are coupled in an ISOP (Input-Series-Output-Parallel) structure.

28. In DC / DC converters, Series resonant DAB converter and A converter controller for controlling the series resonant DAB converter is included. The series resonant DAB converter comprises: an input circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected in series according to a half-bridge configuration, a first capacitor connected in parallel to the first switching element and the second switching element, and a second capacitor connected in parallel to the third switching element and the fourth switching element; an output circuit including a first switching element, a second switching element, a third switching element and a fourth switching element connected according to a full bridge configuration; A DC / DC converter including a resonant circuit and a transformer connected between the input circuit and the output circuit.

29. In claim 28, The resonant circuit and the transformer described are coupled between a connection node of the first switching element and the second switching element of the input circuit and a connection node of the third switching element and the fourth switching element, the resonant circuit includes a capacitor and an inductor connected in series with each other; one terminal of a primary side of the transformer is connected to the resonant circuit, and the other terminal of the primary side is connected to a connection node of a third switching element and a fourth switching element of the input circuit; A DC / DC converter, wherein one terminal of the secondary side of the transformer is connected to a connection node of a first switching element and a second switching element of the output circuit, and the other terminal of the secondary side is connected to a connection node of a third switching element and a fourth switching element of the output circuit.

30. In claim 28, The converter controller described herein comprises: The input circuit includes a control logic for applying a first switching sequence to the first switching element and the second switching element of the input circuit in a complementary manner, and applying a second switching sequence to the third switching element and the fourth switching element in a complementary manner, the first switching sequence is a sequence in which a first pulse having a pulse width and a first level amplitude during a reference time (T / 2), a second pulse having a pulse width and a second level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, a third pulse having a pulse width and the first level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a second level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time are periodically repeated; The second switching sequence is a sequence in which a first pulse having a pulse width and a second level amplitude during a reference time (T / 2), a second pulse having a pulse width and a first level amplitude during a time (T / 2+ΔT) obtained by adding a predetermined time to the reference time, a third pulse having a pulse width and a second level amplitude during the reference time (T / 2), and a fourth pulse having a pulse width and a first level amplitude during a time (T / 2-ΔT) obtained by subtracting a predetermined time from the reference time, are periodically repeated; The first level is a high level, and the second level is a low level as distinguished from the first level.

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