CN110112933B

CN110112933B - Auxiliary inverter

Info

Publication number: CN110112933B
Application number: CN201910469162.2A
Authority: CN
Inventors: 宫兆超; 田以涛; 邓泽航; 韩国风
Original assignee: CRRC Qingdao Sifang Rolling Stock Research Institute Co Ltd
Current assignee: CRRC Qingdao Sifang Rolling Stock Research Institute Co Ltd
Priority date: 2019-05-31
Filing date: 2019-05-31
Publication date: 2020-09-25
Anticipated expiration: 2039-05-31
Also published as: CN110112933A

Abstract

The invention relates to an auxiliary inversion device, wherein a box body structure of the auxiliary inversion device is divided into a first inversion chamber, a middle inversion chamber and a second inversion chamber, the first inversion chamber is riveted in sequence through a shielding plate arranged transversely along the box body structure and is used for bearing a transformer and a reactor, the middle inversion chamber is used for bearing an inverter power module, a charger module and an emergency starting module, and the second inversion chamber is used for bearing a fan assembly; the box body structure adopts a split riveting design, each single chamber is arranged and then spliced together, the mutual influence of the chambers is small, the structure is compact, and the sealing performance is good; meanwhile, a plurality of redundant air ducts are arranged to effectively dissipate heat.

Description

Auxiliary inverter

Technical Field

The invention belongs to the technical field of inverters, and particularly relates to an auxiliary inverter of the inverter.

Background

With the development of rail transit, the integration level of the system is gradually improved, the capacity of the auxiliary inverter is continuously increased, and the heat dissipation requirement is increased. Meanwhile, the box body is usually in an exposed environment, and the sealing requirement is more severe.

Currently, increasing the size of the box is generally adopted to arrange more devices, or to add devices without increasing the size, so as to increase the system capacity, but the increase of the devices leads to further increase of the heat dissipation requirement. For the heat dissipation treatment, the forced air cooling is usually performed on the devices inside the box body through the fan and the air duct to dissipate heat, but in the traditional forced air cooling heat dissipation mode, once the fan fails, the heating devices cannot work normally, so that the heat dissipation treatment has great threat to the normal operation of the vehicle. For sealing treatment, usually, by arranging a double-layer sealing rubber strip structure, the sealing grade of a box body is improved from the traditional IP55 to an IP65 mode and the like, but the service life of an inverter is difficult to match with the replacement period of a sealing strip, so that the production cost is increased and the maintenance cost is improved, and the traditional IP65 sealing grade can not meet the use requirement. Moreover, the auxiliary inverter mostly uses an inverter cabinet body formed by welding with a frame, but has larger deformation, insufficient precision and waste of manpower, financial resources and material resources in the welding process; the frame is usually made of sectional materials, so that the problems of high cost, high mold opening cost, long period and the like exist, and the production period and the production cost are obviously increased.

Therefore, it is necessary to provide a new auxiliary inverter device by improving the structure of the conventional auxiliary inverter in combination with the design of the conventional auxiliary inverter.

Disclosure of Invention

Aiming at the defects of the conventional auxiliary inverter, the invention provides the auxiliary inverter, the box body structure adopts a split riveting structure design, the independent chambers are arranged and riveted together, the mutual influence among the chambers is small, and the sealing performance is good. Meanwhile, a redundant air duct structure is arranged, and heat is effectively dissipated.

In order to achieve the purpose, the invention provides an auxiliary inverter device which comprises a box body structure and is characterized in that the box body structure is provided with a first inverter chamber, a middle inverter chamber and a second inverter chamber, wherein the first inverter chamber is used for bearing a transformer and a reactor, the middle inverter chamber is used for bearing an inverter power module, a charger module and an emergency starting module, and the first inverter chamber is riveted in sequence through a shielding plate arranged along the box body structure; and the second inversion chamber is internally provided with a partition board which is horizontally arranged up and down along the vertical direction of the second inversion chamber, and the second inversion chamber is partitioned into a fan control chamber for bearing a fan controller and a fan chamber for bearing a fan.

Preferably, the first inversion chamber is provided with a detachable first upper cover plate and a first side cover plate, the middle inversion chamber is provided with a detachable middle upper cover plate, and the fan chamber is provided with a detachable second side cover plate; the first side cover plate is provided with a heat dissipation opening for heat dissipation and a filter screen, and the second side cover plate is provided with a louver opening and the filter screen.

Preferably, a first detachable bottom cover plate is arranged at the bottom of the box structure, a first air duct is formed in an inner cavity between the outer side wall of the bottom of the middle inverter chamber and the first bottom cover plate, one end of the first air duct can be communicated with the fan chamber, and the other end of the first air duct can be communicated with the first inverter chamber.

Preferably, a centrifugal fan and a second power supply used for supplying power to the centrifugal fan are arranged on the inner wall of the middle inverter chamber, and a second air channel is formed by the inner wall of the middle inverter chamber and a cavity among the inverter power module, the charger module and the emergency starting module.

Preferably, the upper surfaces of the first upper cover plate, the middle upper cover plate and the second side cover plate are provided with trample prevention structures, and the upper surfaces of the first upper cover plate, the middle upper cover plate and the second side cover plate are respectively provided with a third air duct communicated along the vertical direction of the third air duct in a cavity between the trample prevention structures.

Preferably, the rear side wall of the middle inverter chamber is provided with a radiating fin.

Preferably, the outer wall of the box structure is subjected to anodic oxidation treatment, the front side wall and the rear side wall of the box structure, the first upper cover plate and the middle upper cover plate are both of a double-layer structure, and a heat insulator is arranged between the double-layer structures.

Preferably, the auxiliary inverter main circuit comprises an inverter main circuit, a charger circuit and an emergency starting power circuit, wherein the inverter power module is designed by adopting the inverter main circuit, the charger module is designed by adopting the charger circuit, and the emergency starting module is designed by adopting the emergency starting power circuit;

the inverter main loop comprises a first direct current input filter circuit, a first DC/DC full-bridge chopper circuit, a first DC/AC inverter circuit and a three-phase alternating current filter circuit which are connected in series; a series circuit consisting of the first DC/AC inverter circuit and the three-phase alternating current filter circuit is connected with the charger circuit in parallel;

the charger circuit comprises a second direct current input filter circuit, a second DC/DC conversion circuit and an output rectification circuit which are connected in sequence, wherein the input end of the second direct current input filter circuit is connected with the output end of the first DC/DC full-bridge chopper circuit;

the first direct current input filter circuit comprises a fuse FU1, a contactor KM1, a first pre-charging circuit and an LC direct current filter circuit; the contactor KM1 is connected with the pre-charging circuit in parallel, the input end of the contactor KM1 is connected with the output end of the fuse FU1, and the output end of the contactor KM1 is connected with the input end of the LC direct-current filter circuit; the second direct-current input filter circuit comprises a contactor KM3, a second pre-charging circuit and an RC direct-current filter circuit, wherein the contactor KM3 is connected with the second pre-charging circuit in parallel, the input end of the contactor KM3 is connected with the output end of the first DC/DC full-bridge chopper circuit, and the output end of the contactor KM3 is connected with the input end of the RC direct-current filter circuit;

the output end of the emergency starting power supply circuit is connected with the input end of the LC direct-current filter circuit, and the emergency starting power supply circuit comprises a third DC/DC conversion circuit and a fuse FU3 which are sequentially connected.

Compared with the prior art, the invention has the advantages and positive effects that:

the invention provides an auxiliary inverter circuit design, wherein an inverter main circuit adopts a conventional input direct current filter circuit, a three-phase inverter circuit and a three-phase alternating current filter circuit design, converts DC750V high voltage into AC380V alternating current and supplies power for a vehicle medium voltage load; meanwhile, the charger circuit is arranged to convert DC750V high voltage into DC24V low voltage to supply power for a vehicle control system, a low voltage load and the like; and an emergency starting power supply circuit is designed, and the storage battery is started in an emergency when under voltage so as to ensure that the auxiliary power supply system can be restarted.

The invention also provides an auxiliary inverter according to the inverter circuit design, the box body structure does not adopt the conventional frame structure design, a split riveting structure is adopted, the independent chambers are arranged and then spliced together, the mutual influence among the chambers is small, and the sealing performance is good. Meanwhile, a three-in-one air channel structure comprising a first air channel (namely an external main air channel), a second air channel (namely an internal circulation air channel) and a third air channel (namely an external natural cooling air channel) is arranged, so that heat is effectively dissipated. The first air channel is arranged outside each cavity, the sealing performance of each independent cavity is guaranteed, the overall sealing effect is better, and the sealing grade of IP67 can be achieved within a certain height range. Compared with the traditional inverter design, the auxiliary inverter device has a more compact structure and meets the requirement of narrow vehicle body installation space; and the sealing and heat dissipation effects are better.

Drawings

FIG. 1 is a main circuit diagram of an inverter of the present invention;

FIG. 2 is a schematic diagram of the structure of an auxiliary inverter according to the present invention;

FIG. 3 is a structural diagram of an auxiliary inverter according to the present invention;

FIG. 4 is a structural diagram of an auxiliary inverter according to the present invention;

FIG. 5 is a top view of the auxiliary inverter of the present invention;

FIG. 6 is a rear view of the auxiliary inverter of the present invention;

FIG. 7 is a schematic view of the external main duct circulation of the present invention;

FIG. 8 is a schematic view of the internal circulation duct of the present invention;

FIG. 9 is a schematic view of the external natural cooling air duct circulation of the present invention;

wherein: 1-a first DC/DC full-bridge chopper circuit, 2-a first DC/AC inverter circuit, 3-a second DC/DC inverter circuit, 4-a third DC/DC inverter circuit, 5-a box structure, 51-a first inverter chamber, 511-a first upper cover plate, 512-a first side cover plate, 5121-a heat dissipation port, 52-a middle inverter chamber, 521-a middle upper cover plate, 522-a heat dissipation plate, 53-a second inverter chamber, 531-a fan control chamber, 532-a fan chamber, 5321-a second side cover plate, 53211-a louver port, 533-a capacitor, 54-a first bottom cover plate, 55-a first air duct, 56-a second air duct, 57-a third air duct, 58-a trample prevention, 6-a fan, 7-a centrifugal fan, 8-second power supply.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are all embodiments of the present application, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "comprises" and "comprising," and any variations thereof, in the description and claims of this application and the drawings described above, are intended to cover non-exclusive inclusions. For example, a process, method, or system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," and "third," etc. are used to distinguish between different objects and are not used to describe a particular order.

Referring to fig. 1, the present invention provides an auxiliary inverter circuit, which includes an inverter main circuit and a charger circuit, wherein the inverter main circuit adopts conventional input DC filter circuit, three-phase inverter circuit and three-phase AC filter circuit designs, and includes a first DC input filter circuit, a first DC/DC full-bridge chopper circuit 1, a first DC/AC inverter circuit 2 and a three-phase AC filter circuit which are connected one by one; the high voltage DC750V is converted into three-phase AC380V AC power for supplying power to the vehicle medium voltage load equipment. The charger circuit is connected in parallel with a series circuit consisting of a first DC/AC inverter circuit 2 and a three-phase alternating current filter circuit, the charger circuit comprises a second DC input filter circuit, a second DC/DC conversion circuit 3 and an output rectification circuit which are sequentially connected, the input end of the second DC input filter circuit is connected with the output end of a first DC/DC full-bridge chopper circuit 1, high-voltage direct current is converted into 24V direct current after high-frequency DC/DC conversion and full-wave rectification, and a control power supply is provided for a vehicle control system and each low-voltage device.

Specifically, as shown in fig. 1, the first dc input filter circuit of the main circuit of the inverter includes a first pre-charge circuit composed of a fuse FU1, a contactor KM1, a contactor KM2 and a series resistor R1, and an LC dc filter circuit, where the contactor KM1 is connected in parallel with the first pre-charge circuit, the input end of the first pre-charge circuit is connected to the output end of the fuse FU1, and the output end of the first pre-charge circuit is connected to the input end of the LC dc filter circuit. The LC direct-current filter circuit consists of a filter reactance and a supporting capacitor C1, and is used for filtering direct-current input voltage harmonic waves and stabilizing input voltage. After the input voltage of the direct current 750V is electrified, the contactor KM2 is closed firstly, and the support capacitor C1 is charged in a current-limiting mode through the pre-charging resistor R1. When the voltage difference between the voltage at the two ends of the supporting capacitor C1 and the input voltage of the direct current 750V is detected to be smaller than the rated voltage difference, the main contactor KM1 is controlled to be closed, the contactor KM2 is disconnected, and the impact of charging current on the supporting capacitor C1 is reduced through the current-limiting charging of the pre-charging resistor R1, so that the service life is prolonged. In the present embodiment, the power module of the auxiliary inverter adopts IGBT devices to form a first DC/DC full-bridge chopper circuit 1 and a first DC/AC inverter circuit 2, and integrates a support capacitor, an output current sensor, a gate drive circuit, an absorption circuit, a low-inductance busbar, a temperature switch, a temperature sensor, and the like. The gate drive circuit receives the PWM control signal sent by the ACU to carry out switching operation on the IGBT, and meanwhile, the functions of overcurrent protection, fault detection and the like of the IGBT are achieved. The low-inductance busbar adopts a multilayer composite busbar, so that stray inductance is small, the turn-off overvoltage formed by di/dt is effectively inhibited, and the IGBT is prevented from being damaged. The power module converts 750V direct current input into high-frequency DC/DC and DC/AC, and then obtains three-phase 380V alternating current through three-phase LC low-pass filtering, and three-phase output protection is realized through a three-phase output contactor.

Similarly, the second direct-current input filter circuit of the charger circuit is basically consistent with the first direct-current input filter circuit of the main loop of the inverter and comprises a second pre-charging circuit and an RC direct-current filter circuit, wherein the second pre-charging circuit is composed of a contactor KM3 and a contactor KM2 series resistor R1, the contactor KM3 is connected with the second pre-charging circuit in parallel, the input end of the second pre-charging circuit is connected with the output end of the first DC/DC full-bridge chopper circuit 1, the output end of the second pre-charging circuit is connected with the input end of the RC direct-current filter circuit, and the output end of. The second DC/DC conversion circuit comprises a chopper circuit, a transformer and the like, high-voltage direct current is chopped and reduced, and then filtering is carried out to obtain DC24V power voltage, so that power is supplied to a low-voltage loop of the whole vehicle. In the embodiment, the charger circuit is designed by adopting an independent DC/DC converter, the output voltage range of the DC/DC converter is matched with the charging characteristic curve of the storage battery, the service life of the direct-current electric equipment is also considered, and the output voltage range of the DC/DC converter can be adjusted by software. The high-voltage input ends of the inverter main circuit and the charger circuit are provided with contactor protection and fuse protection, when any DC/DC converter does not work, the DC/DC converter can display the signals on a display of a cab, the work of any DC load is not influenced, and the normal operation of a vehicle is met.

In this embodiment, an emergency start power supply circuit is further designed, an output end of the emergency start power supply circuit is connected to an input end of an LC direct-current filter circuit of the inverter main circuit, and the emergency start power supply circuit includes a third DC/DC conversion circuit 4 and a fuse FU3, which are connected in sequence. After the emergency starting power supply detects high voltage and low voltage of the storage battery, the emergency starting power supply is automatically started to output DC24V voltage, control electricity is provided for a charger and an auxiliary inverter, and the auxiliary power supply system can be restarted.

In the embodiment, the whole vehicle is provided with two auxiliary inverters, and the auxiliary systems can be in parallel connection. After one auxiliary inverter fails, the output contactor of the corresponding auxiliary inverter is automatically disconnected, the vehicle alternating-current bus is isolated from the auxiliary inverter, the other auxiliary inverter is automatically switched to supply power to all alternating-current loads of the vehicle, the vehicle is normally operated under the condition that the power of the loads is reduced, and the redundancy design is guaranteed. The whole system has the functions of self-diagnosis and fault data recording, and simultaneously has the function of network communication with the train bus MVB, so that network control is realized, and the state and the fault condition can be displayed on a display screen of a cab.

In this embodiment, an inverter power module, a charger module, an emergency start module, and the like are respectively designed according to the auxiliary inverter circuit. Referring to fig. 3, 4 and 5, the invention further provides an auxiliary inverter device, which comprises a box structure 5, wherein the box structure 5 is divided into a first inverter chamber 51, a middle inverter chamber 52 and a second inverter chamber 53, the first inverter chamber 51 is used for bearing a transformer and a reactor, the first inverter chamber 51 is used for bearing the inverter power module, the charger module and the emergency starting module, and the first inverter chamber 51 is riveted in sequence through a shielding plate arranged along the box structure 5; two isolation plates horizontally arranged up and down are arranged in the second inversion chamber 53 along the vertical direction of the second inversion chamber, and the second inversion chamber 53 is partitioned into a fan control chamber 531 for bearing a fan controller, a fan chamber 532 for bearing a fan and a capacitor chamber 533 for bearing a capacitor component. The first inverter chamber 51 is designed to be an open cavity structure, the second inverter chamber 52 is designed to be a closed cavity structure, the fan control chamber 531 and the electric chamber 533 are designed to be a closed cavity structure, and the fan chamber 532 is designed to be an open cavity structure, as shown in fig. 2 and 3.

Specifically, as further shown in fig. 3 and 4, in the present embodiment, a detachable first bottom cover plate 54 is disposed at the bottom of the box structure 5, the first inverter chamber 51 is disposed with a detachable first upper cover plate 511 and a first side cover plate 512, the first side cover plate 512 is disposed with a heat dissipation opening 5121 for dissipating heat and a filter screen, and the first inverter chamber 51 is effectively prevented from entering impurities by adopting a double-filter design. The fan room 532 is provided with a detachable second side shield plate 5321, and the second side shield plate 5321 is provided with a louver opening 53211 and a filter screen to prevent impurities from entering the fan room 532. The middle inverter room 52 is provided with a detachable middle upper cover plate 521, the middle inverter room 52 is a closed room after the middle upper cover plate 521 is closed, an inner cavity between the outer side wall of the bottom of the middle inverter room 521 and the first bottom cover plate 54 forms a first air duct 55, one end of the first air duct 55 can be communicated with the fan room 532, and the other end can be communicated with the first inverter room 51 to form an external main air duct, as shown in fig. 6 and 7. The fan 6 is placed in the fan chamber 532 and drafts air through the louver air openings 53211 of the second side cover plate 5321, the air openings drafts air and then enters the first air duct 55 at the bottom to dissipate heat of the charger module, the inverter power module and the emergency starting module in the middle inverter chamber 52, and then enters the first inverter chamber 51 to dissipate heat of elements such as a reactor and a transformer and then is supplied with air through the heat dissipation opening 5121 of the first side cover plate 512. This radiating mode is through an wind channel for the heat dissipation of components and parts in a plurality of cavities, compares the design of other supplementary dc-to-ac converters, more effectual utilized product inner space structure, design reasonable more convenient. And the first air duct 55 is arranged outside the middle inversion chamber 52, so that the sealing performance of each independent chamber is ensured, and the overall sealing effect is better. Meanwhile, in the embodiment, the first inverter room 51 and the fan room 532 are designed to be open cavity structures, so that the cover plates of the air inlet and the air outlet are convenient to replace and maintain when in failure; simultaneously, each cavity all is provided with detachable apron and cover plate, provides convenience for the maintenance of each cavity in the box use, the maintenance and the fault detection of the product of being convenient for.

Referring further to fig. 3 and 4, in the present embodiment, the inverter power module, the charger module and the emergency start module are disposed at the center of the middle inverter chamber 52, and a second air duct 56, i.e., an internal circulation air duct of the middle inverter chamber 52, is formed by the cavity between the inner wall of the middle inverter chamber 52 and the inverter power module, the charger module and the emergency start module, as shown in fig. 8. The centrifugal fan 7 and the second power supply 8 used for supplying power to the centrifugal fan 7 are arranged on the inner wall of the middle inversion chamber 52, the voltage of the second power supply is different from the voltage of the first power supply arranged on the fan 6 of the fan control chamber 531, when the centrifugal fan 7 is started, the heat distribution in the middle inversion chamber 52 is more uniform, local overheating is avoided, and the service life of each component designed in the middle inversion chamber 52 is further prolonged.

As further shown in fig. 3 and 4, in the present embodiment, the first upper cover 511 disposed on the first inverter room 51, the middle upper cover 521 disposed on the middle inverter room 52, and the second side cover 5321 disposed on the fan room 532 are all provided with the anti-stepping structures 58 on the upper surfaces thereof, so as to prevent the deformation of the cover of each inverter room caused by the product stepping on the box during use and the influence on the sealing performance of the box. The cavity between the upper surfaces of the first upper cover 511, the middle upper cover 521 and the second side cover 5321 and the anti-stepping structure 58 is formed with a third air duct 57 communicated along the vertical direction, the air duct is an external natural cooling air duct, the air circulation mode is as shown in fig. 9, the rear side wall of the middle inverter chamber 52 is provided with a heat sink 522, no device is added in the air duct, and the heat is effectively dissipated by using the traveling wind.

The box structure 5 of this embodiment adopts the aluminum alloy material, mainly uses riveted production technology to reduce weight and heat altered shape, the inside frame construction that does not use of box not only effectively utilized the inner space to the at utmost, alleviateed the weight of box moreover to a certain extent, avoided simultaneously that the welding leads to in the frame production process box precision is not enough, extravagant manpower, financial resources, material resources in the school shape process. The outer wall of the box structure is subjected to anodic oxidation treatment, so that surface spraying treatment is avoided, and better heat dissipation is realized. The front and rear side walls of the box structure, the first upper cover plate 511 and the middle upper cover plate 521 are both arranged to be of double-layer structures, and a heat insulator (such as heat insulation cotton) is arranged between the double-layer structures to reduce the influence of sunlight exposure on the temperature in the box body.

In conclusion, the auxiliary inverter disclosed by the invention has the advantages that the box body structure does not adopt a conventional frame structure design, a split riveting structure is adopted, the independent chambers are arranged and then spliced together, the chambers have small mutual influence, and the sealing property is good. Meanwhile, the box body is provided with a redundant air duct structure for heat dissipation, the structural size of a product is not increased, the weight of the product is not increased, and the heat dissipation effect is obviously improved. Compared with the traditional auxiliary inverter design, the auxiliary inverter device has the advantages of more compact structure, reasonable layout, high integration level, good maintainability and good anti-vibration effect, and meets the requirement of narrow vehicle body installation space; and the sealing and heat dissipation effects are better, and the sealing grade of IP67 can be achieved within a certain height range.

Claims

1. An auxiliary inverter device comprises a main circuit, a charging circuit and an emergency starting power supply circuit, wherein the main circuit comprises an inverter main circuit; the main loop of the inverter comprises a first direct current input filter circuit, a first DC/DC full-bridge chopper circuit, a first DC/AC inverter circuit and a three-phase alternating current filter circuit which are connected in series; the charger circuit is connected in parallel with a series circuit consisting of a first DC/AC inverter circuit and a three-phase alternating current filter circuit, and comprises a second DC input filter circuit, a second DC/DC conversion circuit and an output rectification circuit which are connected in sequence; the emergency starting power supply circuit comprises a third DC/DC conversion circuit, is connected to the output end of the first DC input filter circuit and is connected with the first DC/DC full-bridge chopper circuit in parallel; the inverter power module is designed by adopting an inverter main loop, the charger module is designed by adopting a charger circuit, and the emergency starting module is designed by adopting an emergency starting power circuit; the method is characterized in that:

the auxiliary inversion device comprises a box body structure, wherein the box body structure is divided into a first inversion chamber, a middle inversion chamber and a second inversion chamber, the first inversion chamber is used for bearing a transformer and a reactor and is riveted in sequence through a shielding plate arranged along the box body structure, the middle inversion chamber is used for bearing an inverter power module, a charger module and an emergency starting module, and the second inversion chamber is used for bearing a fan assembly; and the second inversion chamber is internally provided with a partition board which is horizontally arranged up and down along the vertical direction of the second inversion chamber, and the second inversion chamber is partitioned into a fan control chamber for bearing a fan controller and a fan chamber for bearing a fan.

2. The auxiliary inverter device according to claim 1, wherein the first inverter room is provided with a first detachable top cover plate and a first side cover plate, the middle inverter room is provided with a middle detachable top cover plate, and the fan room is provided with a second detachable side cover plate; the first side cover plate is provided with a heat dissipation opening for heat dissipation and a filter screen, and the second side cover plate is provided with a louver opening and the filter screen.

3. The auxiliary inverter device as claimed in claim 2, wherein a first detachable bottom cover plate is disposed at the bottom of the box structure, and an inner cavity between the bottom outer sidewall of the intermediate inverter chamber and the first bottom cover plate forms a first air duct, one end of the first air duct is connected to the fan chamber, and the other end of the first air duct is connected to the first inverter chamber.

4. The auxiliary inverter device as claimed in any one of claims 2 or 3, wherein a centrifugal fan and a second power supply for supplying power to the centrifugal fan are disposed on an inner wall of the intermediate inverter chamber, and a second air duct is formed by a cavity between the inner wall of the intermediate inverter chamber and the inverter power module, the charger module and the emergency starting module.

5. The auxiliary inverter of claim 4, wherein the upper surfaces of the first upper cover plate, the middle upper cover plate and the second side cover plate are provided with anti-stepping structures, and the cavities between the upper surfaces of the first upper cover plate, the middle upper cover plate and the second side cover plate and the anti-stepping structures are respectively provided with a third air duct communicated along the vertical direction of the third air duct.

6. The auxiliary inverter device as claimed in claim 5, wherein a heat sink is provided on a rear sidewall of the intermediate inverter chamber.

7. The auxiliary inverter as claimed in claim 2, wherein the outer wall of the box structure is anodized, the front and rear side walls of the box structure and the first and middle upper cover plates are formed as a double-layer structure, and a heat insulator is disposed between the double-layer structure.

8. The auxiliary inverter of claim 1, wherein the first dc input filter circuit comprises a fuse FU1, a contactor KM1, a first pre-charge circuit, and an LC dc filter circuit; the contactor KM1 is connected with the first pre-charging circuit in parallel, the input end of the contactor KM1 is connected with the output end of the fuse FU1, and the output end of the contactor KM1 is connected with the input end of the LC direct-current filter circuit; the second direct current input filter circuit comprises a contactor KM3, a second pre-charging circuit and an RC direct current filter circuit, the contactor KM3 is connected with the second pre-charging circuit in parallel, the input end of the contactor KM3 is connected with the output end of the first DC/DC full-bridge chopper circuit, and the output end of the contactor KM3 is connected with the input end of the RC direct current filter circuit.