Converter system

Abstract

The utility model discloses a converter system, and relates to the technical field of vehicle engineering. The converter system comprises a converter body formed by cascading a plurality of same basic power subunits, the input end of the converter body is used for being directly connected with a single-phase traction network, and the output end of the converter body is used for independently driving a plurality of traction motors. The output end of the converter body is provided with a three-phase output filter capacitor. According to the converter system, the basic power subunits are cascaded to form the converter main body, so that the current-carrying capability and the voltage endurance capability can be improved; and the output end of the converter main body is provided with a three-phase output filter capacitor, so that when the transformer main body outputs voltage to drive the traction motor, the torque ripple and electromagnetic noise of the traction motor can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of vehicle engineering technology, and in particular to a converter system. Background Technology

[0002] Currently, although many OEMs in my country adopt different technical approaches in the design of traction drive systems, they are basically composed of power frequency traction transformers and traction converters.

[0003] Limited by the technical characteristics of silicon IGBT devices, traditional traction converters have limited room for improvement in terms of weight reduction and energy efficiency. Furthermore, when operating at high speeds, the low switching frequency of traditional silicon converters can lead to severe distortion of the motor current, resulting in torque ripple and electromagnetic noise.

[0004] Therefore, railway locomotives and rolling stock need a new technology to promote the development of traction transmission technology in order to reduce torque pulsation and electromagnetic noise generated by the traction system. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a converter system that can reduce torque pulsation and electromagnetic noise generated during operation.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A converter system includes a converter body formed by cascading multiple identical basic power sub-units. The input end of the converter body is used to directly connect to a single-phase traction network, and the output end is used to independently drive multiple traction motors. The output end of the converter body has a three-phase output filter capacitor.

[0008] For example, the basic power sub-unit includes a front-stage AC / DC rectifier, an intermediate-stage DC / DC converter, and a rear-stage DC / AC inverter; the intermediate-stage DC / DC converter is a CLLC high-frequency resonant converter.

[0009] For example, the front-end AC / DC rectifier is also configured with an input filter inductor.

[0010] For example, the downstream DC / AC inverter is also configured with an output filter inductor.

[0011] For example, the downstream DC / AC inverter is a downstream single-phase DC / AC inverter, and multiple downstream single-phase DC / AC inverters are cascaded to form a multi-stage cascaded three-phase DC / AC inverter.

[0012] For example, when driving the traction motor, each phase employs multiple cascaded downstream single-phase DC / AC inverters.

[0013] For example, when driving the traction motor, each phase uses an inverter unit composed of multiple downstream single-phase DC / AC inverters; in the inverter unit, all the downstream single-phase DC / AC inverters are grouped together, and multiple downstream single-phase DC / AC inverters within a group are cascaded to form a cascaded inverter group, and different cascaded inverter groups are connected in parallel.

[0014] For example, the output of the converter body is also used to provide auxiliary power.

[0015] For example, the basic power sub-unit adopts an all-SiC power unit.

[0016] For example, the basic power subunit communicates via plastic optical fiber based on a fast serial protocol.

[0017] The converter system provided by this utility model includes a converter body formed by cascading multiple identical basic power sub-units. The input end of the converter body is used to directly connect to a single-phase traction network, and the output end is used to independently drive multiple traction motors. The output end of the converter body has a three-phase output filter capacitor.

[0018] This type of converter system, which forms the main body of the converter by cascading basic power sub-units, can improve the current carrying capacity and withstand voltage to meet the current requirements of high-speed trains. Each basic power sub-unit can synchronize events through coordinated control. The output terminal of the main body of the converter has a three-phase output filter capacitor, which can help reduce the torque pulsation and electromagnetic noise of the traction motor when the output voltage of the main body of the transformer drives the traction motor. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the converter system structure provided in a specific embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the downstream three-phase four-stage cascaded inverter scheme of the converter system provided in a specific embodiment of this utility model;

[0022] Figure 3 A schematic diagram of the downstream three-phase parallel two-stage cascaded inverter scheme of the converter system provided in a specific embodiment of this utility model;

[0023] Figure 4A simplified schematic diagram of the basic power subunit for driving a three-phase traction motor in the converter system provided in a specific embodiment of this utility model;

[0024] Figure 5 A schematic diagram of the specific structure of the basic power subunit used to drive a three-phase traction motor in the converter system of the present invention, provided in specific embodiment four.

[0025] Figure 6 A simplified schematic diagram of the basic power sub-unit used to drive a three-phase auxiliary power supply in a converter system provided in a specific embodiment of this utility model;

[0026] Figure 7 A schematic diagram of the specific structure of the basic power subunit used to drive the three-phase auxiliary power supply in the converter system of the present invention, according to a specific embodiment four.

[0027] Figure 8 The diagram below illustrates a communication scheme for a converter system using multiple MCUs as the main control chips, as provided in a specific embodiment of this utility model. Solid arrows pointing left and right indicate data lines, while solid arrows pointing up and down indicate emergency stop lines.

[0028] Figure 9 This is a schematic diagram of a communication scheme for a converter system using an FPGA as the main control chip, provided as a specific embodiment of the present invention. Solid arrows pointing left and right indicate data lines, and solid arrows pointing up and down indicate emergency stop lines.

[0029] Figure 10 This is a front view of the internal structure of the converter system provided in a specific embodiment of the present invention.

[0030] Figure label:

[0031] 1-Traction motor;

[0032] 2-Pre-stage AC / DC rectifier, 21-Input filter inductor;

[0033] 3-Intermediate stage DC / DC converter;

[0034] 4-Post-stage DC / AC inverter, 41-Output filter inductor;

[0035] 5-Converter body, 51-Three-phase output filter capacitor;

[0036] 6-Single-phase traction network;

[0037] 7-Current limiting surge protection components;

[0038] 8-Basic power sub-unit;

[0039] 9-Main control unit. Detailed Implementation

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0041] The core of this invention is to provide a converter system that can reduce torque pulsation and electromagnetic noise generated during operation.

[0042] For a specific embodiment of the converter system provided by this utility model, please refer to the following: Figures 1 to 10 The converter body 5 consists of multiple identical basic power sub-units cascaded together. For example, Figure 1 As shown, the input end of the converter body 5 is used to directly connect to the single-phase traction network 6, and the output end is used to independently drive multiple traction motors 1. The traction motor 1 is specifically a three-phase traction motor. The converter body 5 can output a three-phase sinusoidal voltage to drive the three-phase traction motor.

[0043] In some embodiments, the basic power sub-unit 8 has 52 units, such as... Figure 1 The basic power sub-units 8, numbered 1 to 52, are cascaded to form an integrated converter system. Of course, other numbers of basic power sub-units 8 can be used as needed. This converter system includes an integrated converter body 5 formed by cascading multiple basic power sub-units 8, employing an electronic power transformer. The converter body 5 is directly connected to the single-phase traction network 6 and can drive multiple traction motors 1. Cascading the basic power sub-units 8 improves current carrying capacity and withstand voltage, meeting the requirements of current high-speed trains. The coordinated control of each basic power sub-unit 8 synchronizes events, such as simultaneous ADC start-up and PWM signal edge synchronization. Simultaneously, it minimizes trigger delays and jitter between the basic power sub-units 8.

[0044] Specifically, such as Figure 1 As shown, the output terminal of the converter body 5 has a three-phase output filter capacitor 51. By setting the three-phase output filter capacitor 51 at the output terminal of the converter body 5, a three-phase sinusoidal voltage can be output to drive the traction motor 1, which helps to reduce torque pulsation and electromagnetic noise of the traction motor 1.

[0045] Furthermore, such as Figure 1 As shown, the basic power sub-unit 8 includes a front-end AC / DC rectifier 2, an intermediate-end DC / DC converter 3, and a rear-end DC / AC inverter 4.

[0046] In some embodiments, the intermediate-stage DC / DC converter 3 is specifically a high-frequency isolated converter. Alternatively, the intermediate-stage DC / DC converter 3 includes a CLLC high-frequency resonant converter, specifically directly configured as an intermediate-stage CLLC high-frequency resonant converter to achieve bidirectional energy flow.

[0047] like Figure 4 As shown, in this intermediate-stage DC / DC converter 3, both the high-voltage side and the low-voltage side are H-bridge structures. The two H-bridge structures are connected by a CLLC resonant unit, which is specifically a transformer. The input and output sides of the transformer both include a series unit of an inductor (L) and a capacitor (C).

[0048] At this point, the converter system adopts a modular design. The transformer body 8 is composed of multiple (e.g., 52) identical basic power sub-units 8 cascaded together. Each basic power sub-unit 8 is a three-stage power conversion structure, including a front-stage AC / DC rectifier 2, an intermediate-stage DC / DC converter 3 (specifically a high-frequency CLLC resonant DC / DC converter), and a rear-stage DC / AC inverter 4. Furthermore, the basic power sub-units 8 can achieve bidirectional energy flow, enabling the integrated converter system composed of multiple (e.g., 52) basic power sub-units 8 to operate in traction drive mode and regenerative braking mode.

[0049] Furthermore, the intermediate-stage CLLC high-frequency resonant converters are independent of each other, and their switching frequency can be fixed at the resonant frequency to achieve maximum efficiency. The output voltage of the cascaded front-stage AC / DC rectifier 2 is adjusted to match the voltage requirements of the subsequent DC / AC inverter 4. In addition, the intermediate-stage DC / DC converter 3 can operate in soft-switching mode, with a switching frequency greater than 150kHz, significantly reducing the size and weight of the high-frequency isolation transformer.

[0050] In some embodiments, such as Figure 1 and Figure 5 As shown, the front-end AC / DC rectifier 2 is also equipped with an input filter inductor 21 to reduce the demand for the input filter inductor on the grid side of the converter main body 5. The input filter inductors 21 are arranged in a distributed manner.

[0051] In some embodiments, such as Figure 1As shown, the front-stage AC / DC rectifier 2 is a front-stage single-phase AC / DC rectifier. Specifically, multiple front-stage single-phase AC / DC rectifiers are cascaded to form a multi-stage cascaded single-phase AC / DC rectifier. For ease of explanation, in a specific embodiment, the converter body 5 uses 52 identical basic power sub-units 8 cascaded together, and the front-stage AC / DC rectifier 2 has 52 stages. Of course, the number of basic power sub-units 8, front-stage AC / DC rectifier 2, intermediate-stage DC / DC converter 3, and rear-stage DC / AC inverter 4 can also be configured as needed.

[0052] At this point, by setting up multi-stage cascaded front-end AC / DC rectifiers 2, the converter system input can be directly connected to the single-phase traction network 6, specifically the 25kV traction network. The cascaded front-end AC / DC rectifiers 2 of the 52 basic power sub-units 8 constitute a 52-stage cascaded AC / DC rectifier. In addition, by carrier phase shifting and unipolar frequency doubling PWM modulation, the equivalent switching frequency of the 52-stage cascaded AC / DC rectifier can be significantly improved, reducing the requirement for the input filter inductor on the grid side of the integrated converter body 5, and realizing the miniaturization and weight reduction of the passive inductor on the input side.

[0053] In some embodiments, such as Figure 1 As shown, the downstream DC / AC inverter 4 is also equipped with an output filter inductor 41, which can further reduce torque ripple and electromagnetic noise. The output filter inductor 41 is arranged in a distributed manner.

[0054] In some embodiments, the downstream DC / AC inverter 4 is a downstream single-phase DC / AC inverter, and multiple downstream single-phase DC / AC inverters are cascaded to form a multi-stage cascaded three-phase DC / AC inverter. Using single-phase DC / AC inverters results in a simple structure and lower installation and maintenance costs.

[0055] Based on this, for example, the downstream DC / AC inverter 4 adopts a three-phase four-stage cascaded inverter scheme. Specifically, when driving the traction motor 1, each phase adopts multiple cascaded downstream single-phase DC / AC inverters.

[0056] In some specific embodiments, such as Figure 2 As shown, it is a basic power sub-unit of 1 to 12 levels cascaded with a traction motor 1. At this time, when driving the traction motor 1, each phase uses 4 downstream single-phase DC / AC inverters. These four downstream single-phase DC / AC inverters form a single-phase four-level cascaded inverter unit.

[0057] Alternatively, in some other embodiments, the downstream DC / AC inverter 4 adopts a three-phase parallel two-stage cascaded inverter scheme. Specifically, when driving the traction motor 1, each phase adopts an inverter unit composed of multiple downstream single-phase DC / AC inverters. In each inverter unit, all downstream single-phase DC / AC inverters are grouped, and multiple downstream single-phase DC / AC inverters within a group are cascaded to form a cascaded inverter group. In each inverter unit, different cascaded inverter groups are connected in parallel.

[0058] In some specific embodiments, such as Figure 3 As shown, it is a basic power sub-unit 8 of cascaded levels 1 to 12 corresponding to a traction motor 1. At this time, when driving the traction motor 1, each phase uses four downstream single-phase DC / AC inverters as an inverter unit. These four downstream single-phase DC / AC inverters are divided into two groups. In each group, two downstream single-phase DC / AC inverters form a cascaded inverter group, specifically a single-phase two-stage cascaded inverter group. Then, the two single-phase two-stage cascaded inverter groups are connected in parallel.

[0059] Furthermore, the output of the converter body 5 is also used to provide auxiliary power. For example... Figure 1 As shown, the basic power sub-units 8 of levels 49-52 are used to provide auxiliary power.

[0060] In some embodiments, please refer to Figure 1 Of the 52 basic power sub-units 8, four basic power sub-units 8 (levels 49 to 52) are used to provide auxiliary power, specifically providing four sets of three-phase 380V auxiliary power; the remaining 48 basic power sub-units 8 are used to drive four traction motors 1, that is, each traction motor 1 is driven by 12 basic power sub-units 8, such as... Figure 1 In this configuration, levels 1 to 12, 13 to 24, 25 to 36, and 37 to 48 are basic power sub-units 8, each driving one of four traction motors 1. Each phase of each traction motor 1 is driven by four basic power sub-units 8, for example... Figure 2 As shown, a traction motor 1, with its U-phase, V-phase, and W-phase driven by basic power sub-units 8 of levels 1 to 4, 5 to 8, and 9 to 12, respectively.

[0061] In the above embodiments, a cascaded 4-level DC / AC inverter is constructed by cascading multiple basic power sub-units (8 units), which can improve the equivalent switching frequency and reduce the size and weight of the output LC filter.

[0062] Furthermore, the basic power sub-unit 8 adopts an all-SiC power unit. Applying SiC technology to rail transit traction drive systems offers several advantages. Firstly, its low-loss characteristics reduce the need for a cooling system. Secondly, its high switching frequency, an order of magnitude higher than traditional Si devices, significantly reduces the size and weight of passive components. Thirdly, SiC's higher blocking voltage, higher operating temperature, and higher switching speed, compared to Si devices, reduce switching losses by 70% at the same switching voltage change rate dv / dt. This enables energy conservation and weight reduction of the entire traction system, achieving energy saving and emission reduction goals.

[0063] In some specific embodiments, the converter body 5 is directly connected to the 25kV traction network at input, and can drive 4 traction motors 1 and provide 4 sets of auxiliary power supplies at output, with a total power greater than 3.25MVA and an overall efficiency greater than 97.5%. Compared with the traditional traction drive system, the efficiency is improved by 3% to 5%. Based on the application of SiC devices and other structural settings, the overall weight of a converter system is 2400kg, which is 43% lighter than the traditional solution.

[0064] Furthermore, the basic power sub-units 8 communicate via plastic optical fiber using the Fast Serial Interface (FSI) protocol, enabling low-latency, stable, and high-speed communication. This protocol also facilitates event-synchronized control of the entire converter system. In some embodiments, the 52 basic power sub-units 8 communicate via plastic optical fiber using the Fast Serial Interface protocol.

[0065] In addition, such as Figure 8 As shown, each basic power subunit 8 is also equipped with an independent emergency communication channel. In a specific embodiment, each of the 52 basic power subunits 8 is equipped with an independent emergency communication channel to enable emergency shutdown under fault conditions.

[0066] In addition, such as Figure 8 As shown, in a specific embodiment, when selecting the main control unit 9 to control the main body of the converter, such as... Figure 8 As shown, the main control unit 9 includes multiple main control MCUs to enable communication using multiple MCUs (Micro Control Units) as main control chips. Specifically, the main control unit 9 includes eight main control MCUs, each corresponding to a 13-level basic power sub-unit 8, and can correspond to one traction motor 1 and one auxiliary power supply. Furthermore, the main control MCUs can communicate with the primary MCU and the secondary MCU.

[0067] Alternatively, in other specific embodiments, such as Figure 9As shown, the main control unit 9 can also use an FPGA (Field-Programmable Gate Array) as the main control chip for communication.

[0068] Furthermore, in the structure of the converter body 5, such as Figure 10 As shown, different basic power sub-units 8 can be stacked in the housing, specifically multiple basic power sub-units 8 can be arranged in three pairs of perpendicular directions.

[0069] The converter system provided in this embodiment is an integrated converter system based on silicon carbide electronic power transformer-sine wave traction inverter, which can be applied to traditional rail transit traction systems. By replacing the original power frequency traction transformer with an electronic power transformer, the weight can be reduced while improving the grid-side harmonic characteristics. The converter body 5 adopts cascaded basic power sub-units 8, which can improve the withstand voltage capability. By setting the output filter inductor 41 and the three-phase output filter capacitor 51, the torque pulsation and electromagnetic noise of the traction motor are reduced when the output three-phase sinusoidal voltage drives the traction motor. The application of SiC technology, with its low loss characteristics and high switching frequency characteristics, can reduce the demand for heat dissipation system and reduce the size and weight of passive components.

[0070] It should be noted that when an element is referred to as "fixing" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as "connecting" another element, it can be directly connected to the other element or there may be an intervening element. Furthermore, in the description of this utility model, unless otherwise stated, "multiple," "multiple roots," and "multiple groups" mean two or more.

[0071] The terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0074] The converter system provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A converter system, characterized by The converter main body (5) is formed by cascading a plurality of identical basic power subunits (8), the input end of the converter main body (5) is used for directly connecting a single-phase traction network (6), and the output end is used for independently driving a plurality of traction motors (1) respectively; the output end of the converter main body (5) is provided with three-phase output filter capacitors (51).

2. The converter system of claim 1, wherein, The basic power subunit (8) comprises a front-stage AC / DC rectifier (2), an intermediate-stage DC / DC converter (3) and a rear-stage DC / AC inverter (4); the intermediate-stage DC / DC converter (3) is a CLLC high-frequency resonant converter.

3. The converter system of claim 2, wherein, The front-stage AC / DC rectifier (2) is further provided with an input filter inductor (21).

4. The converter system of claim 2, wherein, The rear-stage DC / AC inverter (4) is further provided with an output filter inductor (41).

5. The converter system of claim 2, wherein, The rear-stage DC / AC inverter (4) is a rear-stage single-phase DC / AC inverter, and a plurality of the rear-stage single-phase DC / AC inverters are connected in cascade to form a multi-stage cascaded three-phase DC / AC inverter.

6. The converter system of claim 5, wherein, When the traction motor (1) is driven, a plurality of cascaded rear-stage single-phase DC / AC inverters are used for each phase.

7. The converter system of claim 5, wherein, When the traction motor (1) is driven, a plurality of rear-stage single-phase DC / AC inverters form an inverter unit for each phase; in the inverter unit, all the rear-stage single-phase DC / AC inverters are grouped, a plurality of the rear-stage single-phase DC / AC inverters in each group are connected in cascade to form a cascaded inverter group, and different cascaded inverter groups are connected in parallel.

8. The converter system according to any one of claims 1 to 7, characterized in that The output end of the converter main body (5) is further used for providing an auxiliary power supply.

9. The converter system according to any one of claims 1 to 7, characterized in that The basic power subunit (8) uses a full-SiC power unit.

10. The converter system according to any one of claims 1 to 7, characterized in that The basic power subunit (8) communicates based on a fast serial protocol through a plastic optical fiber.

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