阅读说明：本技术 高频辅助变流器及控制方法 (High-frequency auxiliary converter and control method ) 是由 杨志浩 毕京斌 何俊鹏 王小旭 吴强 李骄松 于 2021-08-18 设计创作，主要内容包括：本发明提供一种高频辅助变流器及控制方法。辅助变流器LLC谐振电路的全桥电路的输入端连接至三电平BUCK电路的输出端,全桥电路的输出端与高频变压器原边连接,高频变压器副边与LLC谐振电路的整流电路输入端连接；逆变电路：输入端与LLC谐振电路的整流电路输出端连接,输出端连接至负载；整流电路与逆变电路集成为功率模块一,三电平BUCK电路、全桥电路集成为功率模块二,安装在箱体内,并行排列在高频变压器两侧。高频辅助变流器控制方法,辅助变流器启动后,三电平BUCK电路先启动工作,LLC全桥电路跟随三电平BUCK电路启动,然后逆变电路和充电机并行启动。该高频辅助变流器具备体积小、重量轻,故障影响低等优点。(The invention provides a high-frequency auxiliary converter and a control method. The input end of a full-bridge circuit of the auxiliary converter LLC resonant circuit is connected to the output end of the three-level BUCK circuit, the output end of the full-bridge circuit is connected with the primary side of the high-frequency transformer, and the secondary side of the high-frequency transformer is connected with the input end of a rectifying circuit of the LLC resonant circuit; an inverter circuit: the input end of the input end is connected with the output end of the rectification circuit of the LLC resonant circuit, and the output end of the input end is connected to the load; the rectification circuit and the inverter circuit are integrated into a first power module, the three-level BUCK circuit and the full-bridge circuit are integrated into a second power module, the second power module is installed in the box body, and the three-level BUCK circuit and the full-bridge circuit are arranged on two sides of the high-frequency transformer in parallel. According to the control method of the high-frequency auxiliary converter, after the auxiliary converter is started, the three-level BUCK circuit is started to work, the LLC full-bridge circuit is started along with the three-level BUCK circuit, and then the inverter circuit and the charger are started in parallel. The high-frequency auxiliary converter has the advantages of small size, light weight, low fault influence and the like.)

1. A high frequency auxiliary converter, comprising:

three-level BUCK circuit: is connected to the input end of the power grid;

LLC resonant circuit: the LLC full-bridge circuit comprises an LLC full-bridge circuit, a high-frequency transformer and an LLC rectifying circuit, wherein the input end of the full-bridge circuit is connected to the output end of a three-level BUCK circuit, the output end of the full-bridge circuit is connected with the primary side of the high-frequency transformer, and the input end of the rectifying circuit is connected with the secondary side of the high-frequency transformer;

an inverter circuit: the input end is connected with the output end of the LLC rectifying circuit, and the output end is connected to a load;

a box body;

the LLC rectifying circuit and the inverter circuit are integrated into a first power module, the three-level BUCK circuit and the LLC full-bridge circuit are integrated into a second power module, and the first power module and the second power module are both arranged in the box body and are positioned on two sides of a wire outlet end of the high-frequency transformer.

2. The high frequency auxiliary converter according to claim 1, further comprising a charger module, wherein an input terminal of the charger module is connected to an output terminal of the three-level BUCK circuit, and an output terminal of the charger module is connected to the battery.

3. The high-frequency auxiliary converter according to claim 2, wherein the charger module is installed in the box body and arranged in parallel with the power module II.

4. The high-frequency auxiliary converter according to claim 1, wherein the high-frequency transforming circuit comprises a high-frequency transformer, copper bars are used for a primary side and a secondary side of the high-frequency transformer, the copper bars on the primary side are connected to the LLC full-bridge circuit, and the copper bars on the secondary side are connected to the diode rectifying circuit of the LLC resonant circuit.

5. The high-frequency auxiliary converter according to claim 2, wherein the auxiliary converter is a double-auxiliary and double-charging motor integrated design, and comprises two sets of three-level BUCK circuits, an LLC resonant circuit, an inverter circuit and a charger circuit; each group is composed of a power module I, a power module II and a charger module; the output ends of the two groups of inverter circuits are connected to the load in parallel, and the output ends of the two groups of charger modules are connected to the storage battery in parallel.

6. The high frequency auxiliary converter according to claim 5, wherein said case comprises:

the first cavity, the second cavity and the third cavity are positioned on the left side, and the three cavities are arranged in a row;

the fourth cavity, the fifth cavity and the sixth cavity are positioned on the right side, and the three cavities are arranged in a row;

the middle cavities are positioned on the left side and the right side and comprise a seventh cavity, an eighth cavity and a ninth cavity;

the fourth cavity and the first cavity are symmetrically arranged, and the first power modules are respectively arranged in the first cavity and the fourth cavity; the second cavity and the fifth cavity are symmetrically arranged, and the two power modules II are respectively arranged in the second cavity and the fifth cavity; the third cavity and the sixth cavity are symmetrically arranged, and the two charger modules are respectively arranged in the third cavity and the sixth cavity;

two high-power high-frequency transformers are installed in the seventh cavity, a fan is installed in the eighth cavity, and a reactor is installed in the ninth cavity.

7. The high frequency auxiliary converter as claimed in claim 1 or 6, wherein a resonant capacitor is mounted on a side wall of the tank near the second side of the power module, and connects the primary side of the high frequency transformer and the second power module.

8. A high frequency auxiliary converter control method, which can be used for controlling the high frequency auxiliary converter of any one of claims 1 to 7, characterized by comprising the following steps:

after the auxiliary converter is started, the three-level BUCK circuit performs self-checking, if the auxiliary converter fails, the auxiliary converter stops, if the auxiliary converter is normal, pre-charging is started, and after the pre-charging is completed, the three-level BUCK circuit is in soft start;

after the three-level BUCK circuit is started, the following steps are executed:

and (4) carrying out fault diagnosis on the LLC full-bridge circuit and the inverter circuit, if the LLC full-bridge circuit and the inverter circuit are in fault, stopping the LLC circuit and the inverter circuit, if the LLC full-bridge circuit and the inverter circuit are in normal, carrying out soft start on the LLC full-bridge circuit, building voltage on the LLC full-bridge circuit, and assisting the soft start of the inverter.

9. The control method of the high frequency auxiliary converter as claimed in claim 8, wherein after the three-level BUCK circuit is started, the following steps are further performed:

and (4) synchronously carrying out fault diagnosis on the charger, if the fault occurs, stopping the charger, and if the fault occurs, starting the charger and executing a storage battery charging strategy.

Technical Field

The invention relates to the technical field of electrical control, in particular to a high-frequency auxiliary converter and a control method.

Background

The auxiliary power supply system is a reliable guarantee for normal work of the vehicle, the auxiliary power supply system converts high-voltage direct current into constant-frequency alternating current (AC380V) and low-voltage control direct current (DC110V), and a charger calculates charging current and charging voltage according to a characteristic curve of the storage battery and ambient temperature to charge the storage battery.

The high-frequency auxiliary converter is used for inputting direct-current voltage on the network side, enabling the direct-current voltage to enter the LLC high-frequency resonant converter after passing through the DC/DC voltage stabilizing circuit, outputting the direct-current voltage to the three-phase inverter through the uncontrolled rectifying circuit after the isolation and transformation of the high-frequency transformer, and obtaining high-quality three-phase alternating current through the output filter circuit. The soft switching characteristic of the LLC resonant circuit reduces the loss of a power device, improves the working frequency of the power device, uses a high-frequency transformer to replace a power frequency transformer, reduces the volume and the weight of a magnetic element, improves the power density of an auxiliary system, reduces the system noise through high frequency, accords with the development trend of small and light weight, high power density and low noise of a rail train, is energy-saving and environment-friendly, and has remarkable advantages.

The medium-high frequency auxiliary converter system in the prior art has the following technical defects:

(1) the high-power high-frequency auxiliary converter has numerous power devices, and if the high-power high-frequency auxiliary converter is designed into a power module, the high-power high-frequency auxiliary converter is large in size, heavy in weight and very difficult to maintain, disassemble and assemble, and once a certain device fails, the whole module needs to be replaced, and the operation and maintenance cost is too high. If according to the difference of tertiary circuit topology, design into two kinds of power modules, design into a DCDC module with three level BUCK circuit and LLC resonant circuit, design into INV contravariant module with supplementary inverter circuit, then two kinds of module power device uneven distribution, DCDC module device is many, bulky, and it is difficult to lead to production and maintenance too many to be qualified for the next round of competitions the point, and INV contravariant module device is few, small, and it is few to be qualified for the next round of competitions the point, and it is convenient to maintain. The two modules have large volume difference and weight difference, the overall production and maintenance are still troublesome, and the effects of convenient maintenance and installation are not realized.

(2) For the integrated auxiliary power supply system circuit topology, the charger mostly adopts the output power from the auxiliary inversion unit or the high-voltage power at the network side. If the charger takes power from the diode rectification output side of the LLC resonant circuit or the auxiliary inverter output AC380V side, the rated capacity of the high-frequency transformer comprises the rated capacity of the charger and is designed to be 135 kW. If the charger gets electricity from the high-voltage input end on the grid side, a switching tube with a high voltage withstanding grade needs to be selected, and the module design needs to consider higher voltage withstanding, so that the cost is increased, and the economical efficiency is poor. Such as the system disclosed in patent CN 102638155B. The topological structure can realize the convenience of electricity taking of the charger, but the electricity taking performance of the charger is limited by the output of the auxiliary inversion unit. And a charger of some auxiliary converter systems adopts grid-side high-voltage power acquisition. For example, patent CN 101249801a discloses an auxiliary converter, where the input voltages of the dc conversion part and the ac conversion part are both from the grid side high voltage, and the withstand voltage level of the charger switching device is high. As for the auxiliary power supply system related to the invention of patent CN111439126A, the charger takes power from the DC600V power supply device, and the rated power of the charger increases the rated capacity of the high-frequency transformer in the DC600V device, and increases the design difficulty, volume, weight and cost of the high-frequency transformer.

Disclosure of Invention

The present invention is directed to solve one of the above technical problems, and provides a high-frequency auxiliary converter system which is small in size, light in weight, and convenient to install and maintain.

In order to achieve the purpose, the invention adopts the technical scheme that:

a high frequency auxiliary converter, integrated dual auxiliary, dual charge machine, comprising:

three-level BUCK circuit: is connected to the input end of the power grid;

LLC resonant circuit: the LLC full-bridge circuit comprises an LLC full-bridge circuit, a high-frequency transformer and an LLC rectifying circuit, wherein the input end of the LLC full-bridge circuit is connected to the output end of the three-level BUCK circuit, the output end of the full-bridge circuit is connected with the primary side of the high-frequency transformer, and the input end of the LLC rectifying circuit is connected with the secondary side of the high-frequency transformer;

an inverter circuit: the input end is connected with the output end of the LLC rectifying circuit, and the output end is connected to a load;

a box body;

the LLC rectifier circuit and the inverter circuit are integrated into a first power module, the three-level BUCK circuit and the LLC full-bridge circuit are integrated into a second power module, and the first power module and the second power module are installed in the box and located on two sides of the high-frequency transformer. The two modules are positioned on the left side and the right side of the wire outlet end of the high-frequency transformer, so that the minimum wiring distance of the primary side and the secondary side of the transformer is ensured, the structural size and the weight of the two modules are ensured to be close, and the problems that one module is too large, the other module is too small, and the installation and the maintenance are difficult are avoided. The structural layout and the module design overcome the influence of a cable wiring path, a wire length and cable bending of the high-frequency transformer on the electrical parameters of the high-frequency transformer, and improve the stability of the resonant circuit.

In some embodiments of the present invention, the battery charger further includes a charger module, an input end of the charger module is connected to an output end of the three-level BUCK circuit, and an output end of the charger module is connected to the storage battery. The design reduces the rated design capacity of the high-power high-frequency transformer, reduces the volume, the weight and the cost of the high-frequency transformer, can select a switching tube with low voltage level, reduces the cost and has high economy.

In some embodiments of the invention, the charger module is installed in the box body and arranged in parallel with the power module II.

In some embodiments of the invention, the primary side and the secondary side of the high-frequency transformer both adopt copper bars, the copper bar on the primary side is connected to the LLC full-bridge circuit, and the copper bar on the secondary side is connected to the diode rectifying circuit of the LLC resonant circuit.

In some embodiments of the invention, the auxiliary converter is designed for double-auxiliary and double-charging motor integration, and comprises two groups of three-level BUCK circuits, an LLC resonance circuit, an inverter circuit and a charger circuit; each group is composed of a power module I, a power module II and a charger module; the output ends of the two groups of inverter circuits are connected to the load in parallel, and the output ends of the two groups of charger modules are connected to the storage battery in parallel.

In some embodiments of the invention, the case comprises:

the first cavity, the second cavity and the third cavity are positioned on the left side, and the three cavities are arranged in a row;

the fourth cavity, the fifth cavity and the sixth cavity are positioned on the right side, and the three cavities are arranged in a row;

the middle cavities are positioned on the left side and the right side and comprise a seventh cavity, an eighth cavity and a ninth cavity;

the fourth cavity and the first cavity are symmetrically arranged, and the first power modules are respectively arranged in the first cavity and the fourth cavity; the second cavity and the fifth cavity are symmetrically arranged, and the two power modules II are respectively arranged in the second cavity and the fifth cavity; the third cavity and the sixth cavity are symmetrically arranged, and the two charger modules are respectively arranged in the third cavity and the sixth cavity;

two high-power high-frequency transformers are installed in the seventh cavity, a fan is installed in the eighth cavity, and a reactor is installed in the ninth cavity.

In some embodiments of the invention, a resonant capacitor is mounted on the side wall of the box body close to one side of the second power module and is connected with the primary side of the high-frequency transformer and the second power module. The resonance capacitor adopts a plurality of capacitor parallel structures, the number of the parallel capacitors can be adjusted according to the resonance effect, and compared with a single resonance capacitor structure, the split structure parameter is flexibly adjusted.

In some embodiments of the present invention, a method for controlling a high-frequency auxiliary converter is further provided, including the following steps:

after the auxiliary converter is started, the three-level BUCK circuit performs self-checking, if the auxiliary converter fails, the auxiliary converter stops, if the auxiliary converter is normal, pre-charging is started, and after pre-charging is completed, the three-level BUCK circuit is in soft start;

after the three-level BUCK circuit is started, the following steps are executed:

performing fault diagnosis on the LLC full-bridge circuit and the inverter circuit, if the LLC full-bridge circuit and the inverter circuit are in fault, stopping the LLC circuit and the inverter circuit, and if the LLC full-bridge circuit and the inverter circuit are in normal, performing soft start on the LLC full-bridge circuit to build voltage and assist the inverter in soft start;

and (4) synchronously carrying out fault diagnosis on the charger, if the fault occurs, stopping the charger, and if the fault occurs, starting the charger and executing a storage battery charging strategy.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

(1) the invention reasonably distributes the power devices of the three-level BUCK circuit, the LLC resonant circuit and the auxiliary inverter circuit, and integrates the device distribution of the power module again. The three-level BUCK circuit and the LLC full bridge circuit are designed into a DCDC module, the high-frequency transformer output diode rectifying circuit and the auxiliary inverter circuit are designed into an INV inverter module, and power devices of the LLC resonant circuit are distributed to the DCDC module and the INV inverter module in a balanced mode. The charger is independently designed with a success rate module. By the design, the three power modules can have small volume and light weight, and the fault influence is low.

(2) The DCDC module and the INV inversion module are structurally positioned on two sides of the high-frequency transformer respectively and connected by adopting short copper bars, the high-frequency transformer is close to the fan, and heat dissipation is preferentially ensured.

(3) The auxiliary converter provided by the invention is an auxiliary converter integrated with double auxiliary motors and double charging motors, the auxiliary inverter and the charging machine are integrated into a box body, the weight and the volume of the cabinet body are reduced, and meanwhile, the two auxiliary motors and the two charging machines work independently, so that the redundancy is improved. According to the design requirements of a standard subway train, the integrated auxiliary converter and the circuit topology are designed according to the box structure and the high-frequency auxiliary converter circuit topology, the box structure layout is effectively fused, three power module units are designed in a balanced mode from the aspects of size and weight, and an integrated control strategy is designed.

(4) The power-taking side of the charger is arranged on the direct-current voltage output by the three-level BUCK, alternating-current square waves are output through the half-bridge inverter circuit, and stable direct-current voltage is output through the rectifying and filtering circuit after isolated voltage transformation is carried out through the high-frequency transformer of the charger to supply power to low-voltage loads on the vehicle and charge the storage battery. According to the topological mode, the charger does not take electricity from alternating current output, the rated design capacity of the high-power high-frequency transformer of the LLC resonant circuit is reduced, the size, the weight and the cost of the high-frequency transformer are reduced, and the advantages are obvious.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a circuit topology diagram of a high frequency auxiliary converter.

Fig. 2 is a structural view of a high-frequency auxiliary converter box.

Fig. 3 is a structural view of a high-frequency auxiliary converter box.

Fig. 4 is a structural view of a high-frequency auxiliary converter box.

Fig. 5 is a flow chart of the control of the high frequency auxiliary converter.

In the above figure:

the power supply comprises a box body 1, a power module I2, a power module II 3, a charger power module 4, a control and communication connector 5, a three-phase alternating current output contactor 6, an integrated direct current reactor L1 7, a fan 8, a high-frequency transformer 9, an integrated three-phase reactor L2 10, a left side box body 11, a right side box body 12, a middle box body 13, an auxiliary side copper bar 14 and an auxiliary side copper bar 15.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a high-frequency auxiliary current transformer, comprising:

three-level BUCK circuit: is connected to the input end of the power grid;

LLC resonant circuit: the LLC full-bridge circuit comprises an LLC full-bridge circuit, a high-frequency transformer and an LLC rectifying circuit, wherein the input end of the full-bridge circuit is connected to the output end of a three-level BUCK circuit, the output end of the LLC full-bridge circuit is connected with the primary side of the high-frequency transformer, and the input end of the LLC rectifying circuit is connected with the secondary side of the high-frequency transformer;

an inverter circuit: the input end is connected with the output end of the LLC rectifying circuit, and the output end is connected to a load;

a box body;

the LLC rectifier circuit and the inverter circuit are integrated into power module I, and three level BUCK circuit, LLC full-bridge circuit are integrated into power module II, and power module I and power module II are all installed in the box, are located the left and right sides of high frequency transformer. The two modules are positioned on the left side and the right side of the wire outlet end of the high-frequency transformer, so that the minimum wiring distance of the primary side and the secondary side of the transformer is ensured, the structural size and the weight of the two modules are ensured to be close, and the problems that one module is too large, the other module is too small, and the installation and the maintenance are difficult are avoided.

The combined design of the power module I and the power module II fully considers the current situations that a large number of power devices of the high-power high-frequency auxiliary converter are provided, if the power module is designed, the size is large, the weight is large, and the maintenance and the dismounting are very difficult, and once a certain device fails, the whole module needs to be replaced, so that the operation and maintenance cost is high.

Based on the principle, the power devices of the three-level BUCK circuit, the LLC resonant circuit and the auxiliary inverter circuit are reasonably distributed, the three-level BUCK circuit and the LLC full bridge circuit are designed into a power module I (defined as a DCDC module), the high-frequency transformer output diode rectifying circuit and the auxiliary inverter circuit are designed into a power module II (defined as an INV inverter module), and the power devices of the LLC resonant circuit are distributed to the DCDC module and the INV inverter module in a balanced mode. The charger is independently designed with a success rate module. By the design, the three power modules can be small in size and light in weight, and meanwhile, the influence of faults is low, such as BUCK circuit faults, only the DCDC module needs to be replaced, and the rest modules are not influenced. The DCDC module of the invention has the size of 450x380x400(mm) and the weight of 60 kg; the size of the INV inversion module is 420x380x380(mm), and the weight is 50 kg; the charger module size is 360x380x400(mm), weight 45 kg.

In some embodiments of the present invention, the battery charger further includes a charger module, an input end of the charger module is connected to an output end of the three-level BUCK circuit, and an output end of the charger module is connected to the storage battery. Different from the prior art, the input voltage of the charger module is direct current voltage output by a three-level BUCK, alternating current square waves are output through a half-bridge inverter circuit, and stable direct current voltage is output through a rectifying and filtering circuit after isolated voltage transformation by a high-frequency transformer in the charger module to supply power to low-voltage loads on a vehicle and charge a storage battery. The charger module is also integrally installed in the box body and arranged in parallel with the power module II, so that the charger module is conveniently connected with the three-level BUCK circuit in a wiring manner. Compared with the LLC resonant output power supply or the auxiliary inverter output power supply, the charger power supply method provided by the invention reduces the rated capacity of the LLC resonant circuit high-frequency transformer, and reduces the volume and the weight, thereby reducing the design and the production difficulty of the high-power high-frequency transformer; compared with a charger directly powered by the high voltage at the network side, the invention reduces the voltage stress of the switch tube, thereby reducing the cost of the switch tube.

In some embodiments of the present invention, a dual auxiliary converter structure is further provided, which includes two sets of three-level BUCK circuits, an LLC resonant circuit, an inverter circuit, and a charger module; each group of auxiliary converters is composed of a power module I, a power module II and a charger module; the output ends of the two groups of inverter circuits are connected to the load in parallel, and the output ends of the two groups of charger modules are connected to the storage battery in parallel. When one auxiliary power supply fails, the other auxiliary power supply can still supply power for medium-voltage and low-voltage loads on the vehicle.

The electrical schematic diagram of the high-power high-frequency auxiliary current transformer is shown in the following figure 1, and the structural layout diagram is shown in the figure 2. The input direct-current voltage of each path of auxiliary power supply outputs stable voltage to the LLC resonant circuit through the three-level BUCK circuit; the LLC resonant circuit outputs voltage which is isolated and transformed by a high-frequency transformer and then is rectified by a diode to output stable voltage to the auxiliary inverter; the output alternating voltage of the auxiliary inverter is supplied to a medium-voltage load on the vehicle through a high-quality 3AC380V alternating voltage obtained by a three-phase LC filter circuit. The input voltage of the charger is from the direct current voltage output by the three-level BUCK, an alternating current square wave is output through the half-bridge inverter circuit, and after isolated voltage transformation is carried out through the high-frequency transformer of the charger, stable direct current voltage is output through the rectifying and filtering circuit to supply power to low-voltage loads on the vehicle and charge the storage battery.

The rated alternating current output capacity of the high-power high-frequency auxiliary converter is 2 × 120kVA, and the rated direct current output capacity is 2 × 15kW, so that only one LLC resonant converter is needed for one auxiliary power supply, and the high-power high-frequency auxiliary converter has the advantages of few devices, small size, low total failure rate and the like, and is first applied to the high-power high-frequency auxiliary converter in the current rail transit field. In the current rail transit field, an important design difficulty of a high-power high-frequency auxiliary converter is a high-power high-frequency transformer. The higher the power grade is, the higher the magnetic core specification of the high-frequency transformer is, the higher the constraints of leakage inductance and excitation inductance are, and the higher the difficulty of controlling temperature rise and noise is.

The high-power high-frequency transformer is a key electric device of the auxiliary converter, and the electrical parameters, particularly the excitation inductance and the leakage inductance, of the high-power high-frequency transformer are required to be kept stable as much as possible under various conditions. If the high-frequency transformer adopts the litz wire to be led out, the change of the excitation inductance can be caused by the difference of the wiring path, the wire length and the bending radian of the litz wire in the production and assembly process, the resonance parameters are influenced, and the resonance abnormity is caused.

In order to solve the technical problem, in some embodiments of the present invention, the primary side and the secondary side of the high-frequency transformer in the high-frequency transformation circuit both use copper bars, the primary side copper bar 15 is connected to the LLC full-bridge circuit, and the secondary side copper bar 14 is connected to the LLC rectification circuit. In order to minimize the parameter influence caused by the connection mode, the power module is designed to be as short as possible from the primary side and secondary side connection points of the high-power high-frequency transformer, the high-frequency transformer is designed to be installed between the DCDC module and the INV inversion module, and the high-power high-frequency transformer is connected by adopting copper bars, as shown in FIG. 4.

The layout structure of the auxiliary converter module in the box body is described below with reference to the accompanying drawings.

In some embodiments of the present invention, the case 1 includes a left side chamber 11, a right side chamber 12, and a middle chamber 13 between the left side chamber 11 and the right side chamber 12.

The first cavity, the second cavity and the third cavity are positioned on the left side, and the three cavities are arranged in a row;

the fourth cavity, the fifth cavity and the sixth cavity are positioned on the right side, and the three cavities are arranged in a row;

the middle cavities are positioned on the left side and the right side and comprise a seventh cavity, an eighth cavity and a ninth cavity;

the fourth cavity and the first cavity are symmetrically arranged, and the two power modules I2 (INV inversion modules) are respectively arranged in the first cavity and the fourth cavity; the second cavity and the fifth cavity are symmetrically arranged, and the two power modules II 3(DCDC modules) are respectively arranged in the second cavity and the fifth cavity; the third cavity and the sixth cavity are symmetrically arranged, and the two charger modules 4 are respectively arranged in the third cavity and the sixth cavity;

a high-frequency voltage transformation circuit 9 part of the two inverters is arranged in the seventh cavity, a fan 8 is arranged in the eighth cavity, and an integrated three-phase reactor L17 is arranged in the ninth cavity. And the three-phase reactor L210 is arranged on the side of the seventh cavity.

Taking the direction shown in fig. 3 as an example, a three-phase ac output contactor KM 36 is installed at the rightmost side of the cavity 13, and ac voltage generated by the auxiliary inverter is output to a medium-voltage load on the vehicle through the three-phase ac output contactor.

The high-power high-frequency transformer is a main heating device of a system, and the performance of a magnetic core is restricted by high temperature, so that the heat dissipation of the high-power high-frequency transformer is preferentially ensured.

In some embodiments of the invention, a resonant capacitor is mounted on the side wall of the box body close to one side of the second power module and is connected with the primary side of the high-frequency transformer and the second power module. The resonance capacitor adopts a plurality of capacitor parallel structures, the number of the parallel capacitors can be adjusted according to the resonance effect, and compared with a single resonance capacitor structure, the split structure parameter is flexibly adjusted.

In some embodiments of the present invention, there is further provided a method for controlling a high-frequency auxiliary converter, referring to fig. 5, including the following steps:

the auxiliary converter is started: and (5) putting control power into the converter to assist the converter to carry out initialization and power-on self-test. The self-test is passed, there is no system fault, the auxiliary converter detects the input high voltage, at which time the auxiliary converter gives a "ready" signal. The train network system synthesizes the ready signals sent by the auxiliary converters, starts the auxiliary converters according to the time sequence and sends starting instructions to the auxiliary converters.

Self-checking of the three-level BUCK circuit: if the auxiliary converter starts after receiving a starting instruction, judging whether a three-level BUCK fault exists, if the fault exists, stopping the auxiliary converter, if the fault exists, starting pre-charging, and after the pre-charging is finished, starting a three-level BUCK circuit in a soft mode; after the pre-charging is finished, the three-level BUCK is in soft start to establish voltage, and meanwhile, the LLC is also in soft start, so that the starting time of the alternating current conversion part is shortened.

After the three-level BUCK circuit is started, the following steps are executed:

self-checking of an LLC full-bridge circuit: after the three-level BUCK output voltage is established, the LLC full-bridge circuit output voltage is also established at the moment, fault diagnosis is carried out on the LLC full-bridge circuit and the inverter circuit, if the fault occurs, the LLC full-bridge circuit and the inverter circuit are stopped, and if the fault occurs, the LLC full-bridge circuit is in soft start to complete voltage establishment of the LLC full-bridge circuit and assist in soft start of the inverter; and (3) assisting the inverter to perform soft start, simultaneously executing a grid-connected strategy, closing the output contactor after the conditions are met, and supplying power to an alternating load on the vehicle.

Self-checking of the charger: and (4) synchronously carrying out fault diagnosis on the charger, stopping the charger if the fault occurs, starting the charger if the fault occurs, and executing a storage battery charging strategy to realize that the direct current load on the vehicle is supplied with power together.

The charger and the auxiliary inverter are independently started to work, and the two control branches are executed in parallel.

The invention provides a control method of an auxiliary converter, which comprises the following steps: the three-level circuit adopts hierarchical control, the mutually independent circuits adopt independent control and run in parallel, the influence of faults on the system can be reduced to the minimum, and the redundancy capability of the system is improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.