High-reliability non-polar high-voltage direct-current contactor for megawatt charging system

Abstract

The utility model provides a high-reliability non-polar high-voltage direct current contactor for a megawatt charging system. The high-reliability non-polar high-voltage direct current contactor comprises a shell, a magnetic circuit assembly, a double-circuit parallel contact system and an arc extinguishing system, the magnetic circuit assembly is installed at the bottom of the shell through a flange plate. A busbar is installed at the top of the shell and connected with an external load. The double-path parallel contact system is arranged at the upper part of the shell, the double-path parallel contact system comprises two paths of movable contact pieces, a static contact column and an auxiliary contact column, and the two paths of movable contact pieces are linked with a core rod through a core rod I respectively. Through the design of the double-path parallel contacts and the arc extinguishing system, high-reliability switching of megawatt-level direct-current loads is realized under the same volume, and the problems of high temperature rise, short service life and insufficient arc extinguishing capability in the prior art are solved; and the contactor has higher redundancy.

Description

Technical Field

[0001] This utility model relates to a highly reliable non-polar high-voltage DC contactor for megawatt-level charging systems. Background Technology

[0002] Currently, with the continuous innovation and development of science and technology, in industries such as fuel cells & solar energy systems, new energy-related infrastructure, and high-power DC equipment, especially in the charging pile industry, the power requirements of power systems are getting higher and higher in order to meet the fast charging needs of new energy vehicles. The power requirements have increased from the previous 120kW, 240kW, 400kW, and 600kW to 720kW, 800kW, 1MW, and 1.5MW. The load current requirements of high-voltage DC contactors are also increasing, from the previous 200A, 300A, and 600A to 800A, 1000A, and 1200A.

[0003] Currently, DC contactors on the market are divided into two types of sealed contactors: ceramic-encapsulated and epoxy-encapsulated. Although most manufacturers claim that their DC contactors can switch under high-power 1000A@1000V DC loads, this is only the contactor's ultimate breaking capacity. It often only meets the requirements for a few connections, or can only carry 1000A current, not 1000A@1000VDC load breaking. This severely affects its reliability as a main power switch, leading to a very high risk of failure in its associated equipment. Furthermore, because DC current, unlike AC current, does not have a zero-point and therefore cannot naturally extinguish the arc, the arc-extinguishing system of the DC contactor directly determines its arc-extinguishing capability. This is especially true under high voltage and high current conditions, where arcing is particularly pronounced, and the arc-extinguishing capability determines the switching capacity and service life of the DC contactor. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a highly reliable non-polar high-voltage DC contactor for megawatt-level charging systems.

[0005] This utility model is achieved through the following technical solution.

[0006] This utility model provides a highly reliable non-polarized high-voltage DC contactor for megawatt-level charging systems, comprising a housing, a magnetic circuit assembly, a dual-path parallel contact system, and an arc-extinguishing system. The magnetic circuit assembly is mounted on the bottom of the housing via a flange, and a busbar is installed on the top of the housing for connection to an external load. The dual-path parallel contact system is located on the upper part of the housing and includes two moving contact pieces, a stationary contact post, and an auxiliary contact post. The two moving contact pieces are each linked to a core rod and reset by a return spring and a contact spring. The stationary contact post and the auxiliary contact post are brazed into ceramic and connected to the busbar. The core rod is movably mounted inside the magnetic circuit assembly and connected to the iron core. The arc-extinguishing system is installed inside the flange, and the contact points between the moving contact pieces and the stationary contact post are located within the arc-extinguishing system.

[0007] The housing includes an outer casing assembly and a cover plate. The outer casing assembly is a stepped cylinder. The upper step of the outer casing assembly supports the edge of the flange. The center of the flange is recessed and riveted to the magnetic circuit assembly. The top edge of the arc extinguishing system is supported on the edge of the flange. The ceramic is located on the top of the arc extinguishing system. The edge of the ceramic is also fixed with a Kovar connecting piece. The lower end of the Kovar connecting piece fills the space between the outer casing assembly and the ceramic and its bottom contacts the nut. The upper end of the Kovar connecting piece presses against the edge of the ceramic and its top contacts the busbar. The cover plate is pressed tightly against the center of the busbar. The four corners of the cover plate are fixed to the outer casing assembly with bolts.

[0008] The two ends of the busbar are fixed with load-bearing screws by flange nuts.

[0009] The arc extinguishing system includes an arc extinguishing cover, the top of which is folded outward and fastened to the edge of the flange. The arc extinguishing cover contains ceramic grid plate one and ceramic grid plate two. Four sets of ceramic grid plate one and ceramic grid plate two are respectively installed opposite each other on both sides of the contact point. The arc extinguishing cover also contains an arc extinguishing magnet, which is arranged with N pole to N pole on both sides of the stationary contact post.

[0010] The arc-extinguishing chamber is filled with a mixture of hydrogen and nitrogen gas.

[0011] Two core rods are installed at both ends of the support assembly, and the center of the support assembly is installed at the top of the core rods. Two strip-shaped moving contact pieces are installed on the two core rods respectively, and the contact spring is installed on the core rods and between the support assembly and the moving contact pieces.

[0012] The support assembly includes a support plate and a support piece. The middle part of the support piece is embedded in the middle part of the support plate. The support plate and the support piece clamp the middle part of the auxiliary point spring. The top of the core rod passes through the support piece, the auxiliary point spring, and the support plate in sequence and is then fixed by a nut.

[0013] The magnetic circuit assembly includes magnetic poles and an iron core. The top of the magnetic poles is riveted to a flange, and the iron core is threaded to the bottom of the core rod. The iron core is covered with a sleeve. The magnetic poles and the iron core are surrounded by a coil frame. A coil is wound on the coil frame, and the outside of the coil is wrapped by an iron yoke. The return spring is located between the magnetic poles and the iron core.

[0014] The magnetic circuit assembly also includes an energy-saving board, which is installed on the outside of the wire package.

[0015] It also includes an insulating pad, which is placed between the arc-extinguishing cover and the flange.

[0016] The beneficial effects of this utility model are as follows: through the design of dual parallel contacts and arc extinguishing system, high-reliability switching of megawatt-level DC loads is achieved in the same volume, solving the problems of high temperature rise, short life and insufficient arc extinguishing capability in the prior art; and giving the contactor higher redundancy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the arc-extinguishing component structure of this utility model;

[0019] Figure 3 This is a schematic diagram of the cover plate structure of this utility model;

[0020] Figure 4 This is a schematic diagram of the arc-extinguishing cover structure of this utility model;

[0021] Figure 5 This is a schematic diagram of the core rod assembly structure of this utility model;

[0022] Figure 6 This is a schematic diagram of the magnetic blowout direction of this utility model;

[0023] In the diagram: 1-Outer casing assembly, 2-Yoke, 3-Insulating pad, 4-Support plate, 5-Nut, 6-Ceramic, 7-Flange nut, 8-Bus, 9-Cover plate, 10-Load mounting screw, 11-Arc extinguishing cover, 12-Kovar connecting piece, 13-Moving contact piece, 14-Support piece, 15-Flange, 16-Magnetic pole, 17-Return spring, 18-Coil coil, 19-Coil frame, 20-Shell, 21-Core rod, 22-Core, 23-Energy saving plate, 24-Upper cup, 25-Micro switch, 26-Upper spring seat, 27-Static contact post, 28-T-nut, 29-Core rod one, 30-Contact spring, 31-Auxiliary contact spring, 32-Ceramic grid plate two, 33-Arc extinguishing magnet, 34-Ceramic grid plate one, 35-Auxiliary contact post. Detailed Implementation

[0024] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0025] A high-reliability non-polar high-voltage DC contactor for megawatt-level charging systems includes a housing, a magnetic circuit assembly, a dual-path parallel contact system, and an arc-extinguishing system. The magnetic circuit assembly is mounted on the bottom of the housing via a flange 15, and a busbar 8 is installed on the top of the housing for connection to an external load. The dual-path parallel contact system is located on the upper part of the housing and includes two moving contact pieces 13, a stationary contact post 27, and an auxiliary contact post 35. The two moving contact pieces 13 are linked to a core rod 21 via a core rod 29 and are reset by a return spring 17 and a contact spring 30. The stationary contact post 27 and the auxiliary contact post 35 are brazed into a ceramic 6 and connected to the busbar 8. The core rod 21 is movably mounted inside the magnetic circuit assembly and connected to an iron core 22. The arc-extinguishing system is installed inside the flange 15, and the contact point between the moving contact piece 13 and the stationary contact post 27 is located within the arc-extinguishing system.

[0026] The outer casing includes an outer cover assembly 1 and a cover plate 9. The outer cover assembly 1 is a stepped cylinder. The upper step of the outer cover assembly 1 supports the edge of the flange 15. The middle of the flange 15 is recessed and riveted to the magnetic circuit assembly. The top edge of the arc extinguishing system is supported on the edge of the flange 15. The ceramic 6 is located on the top of the arc extinguishing system. The edge of the ceramic 6 is also fixed with a Kovar connecting piece 12. The lower end of the Kovar connecting piece 12 is filled between the outer cover assembly 1 and the ceramic 6 and its bottom contacts the nut 5. The upper end of the Kovar connecting piece 12 is pressed against the edge of the ceramic 6 and its top contacts the busbar 8. The cover plate 9 is pressed tightly against the middle of the busbar 8. The four corners of the cover plate 9 are fixed to the outer cover assembly 1 by bolts.

[0027] The two ends of the busbar 8 are fixedly mounted with load mounting screws 10 by flange nuts 7.

[0028] The arc extinguishing system includes an arc extinguishing cover 11, the top of which is folded outward and fastened to the edge of the flange 15. The arc extinguishing cover 11 contains ceramic grid plate 34 and ceramic grid plate 32. The four sets of ceramic grid plate 34 and ceramic grid plate 32 are respectively installed opposite to each other on both sides of the contact point. The arc extinguishing cover 11 also contains an arc extinguishing magnet 33, which is arranged with N pole to N pole on both sides of the stationary contact post 27.

[0029] The arc-extinguishing hood 11 is filled with a mixture of hydrogen and nitrogen gas.

[0030] Two core rods 29 are installed at both ends of the support assembly, the center of the support assembly is installed at the top of the core rod 21, two strip-shaped moving contact pieces 13 are respectively installed on the two core rods 29, and the contact spring 30 is installed on the core rods 29 and between the support assembly and the moving contact pieces 13.

[0031] The support assembly includes a support plate 4 and a support piece 14. The middle part of the support piece 14 is embedded in the middle part of the support plate 4. The support plate 4 and the support piece 14 clamp the middle part of the auxiliary point spring 31. The top of the core rod 21 passes through the support piece 14, the auxiliary point spring 31 and the support plate 4 in sequence and is then fixed by a nut.

[0032] The magnetic circuit assembly includes a magnetic pole 16 and an iron core 22. The top of the magnetic pole 16 is riveted to the flange 15. The iron core 22 is threaded to the bottom of the core rod 21. The iron core 22 is covered by a sleeve 20. The magnetic pole 16 and the iron core 22 are surrounded by a coil frame 19. A coil 18 is wound on the coil frame 19. The outside of the coil 18 is wrapped by an iron yoke 2. The return spring 17 is located between the magnetic pole 16 and the iron core 22.

[0033] The magnetic circuit assembly also includes an energy-saving board 23, which is installed on the outside of the inline package 18.

[0034] It also includes an insulating pad 3, which is located between the arc-extinguishing cover 11 and the flange 15.

[0035] When the coil is energized, the input voltage forms a pulse signal with a specific duty cycle through the PWM pulse width modulation circuit. The coil 18 generates a magnetic field, which passes through the magnetic pole 16, iron core 22, and flange 15 riveted to the magnetic pole 16 of the coil frame 19, as well as the iron yoke 2, forming a magnetic circuit. This magnetizes the magnetic pole 16 and iron core 22. The magnetized magnetic pole 16 and iron core 22 tend to attract each other, causing them to move. During this movement, the two moving contact pieces 13 connected to the core rod 21 move towards the stationary contact post 27, thus connecting the moving and stationary contacts. When the coil 18 is de-energized, the magnetized magnetic pole 16 and iron core 22 quickly demagnetize, and the electromagnetic attraction disappears rapidly. During the movement of the core rod 21, the compressed return spring 17 and contact spring 30 generate a return force, causing the moving and stationary contacts to disconnect. The auxiliary contacts work similarly. The core rod assembly drives the auxiliary contact spring 31 to move up and down, connecting and disconnecting with the micro switch 25, thereby realizing the connection and disconnection of the auxiliary contacts.

[0036] The high rated load (1000A / 1000V) required for startup of this application is met by a PWM pulse width modulation circuit. The principle is as follows: input Ui: DC9V~DC36V, output: first a rectangular pulse (starting coil) with a duration greater than 100ms and an amplitude equal to Ui, followed by a rectangular wave with an amplitude Ui and a period of 58μs. The duty cycle is related to the input voltage. For example, when the input is DC12V, the duty cycle is 22:36; when the input is 24V, the duty cycle is 11:47; and when the input is DC36V, the duty cycle is 7.3:50.7, which ensures that a certain magnetic flux is generated per unit period.

[0037] 2.2 High load capacity of 1000A / 1000V and temperature rise guarantee design: The contact end is designed for two parallel connections. A crossbar drives two moving contact pieces to contact and separate from the stationary contact post. One coil 18 drives the two circuits to work simultaneously, and the synchronization is higher than that of parallel contactors controlled by two coils.

[0038] Furthermore, this invention employs a dual-moving-plate design, giving it a higher current-carrying capacity. The dual-moving-plate reduces the load compared to a single-moving-plate design by shunting the current, thus reducing heat generation and wear. Within a specified volume, it offers a larger current-carrying area than a single-plate design. The dual-moving-plate design also provides redundancy; even if one circuit has poor contact, the other can still maintain circuit continuity, reducing the risk of unexpected power outages and making it more suitable for high-reliability operating conditions. The parallel connection of the dual-moving-plates reduces total contact resistance, decreasing energy loss and temperature rise, thus improving energy efficiency. The current shunting by the dual-moving-plates reduces arc erosion of the contacts, while the dual-moving-plate design accelerates arc extinguishing, extending service life. The dual-moving-plates share mechanical impact, reducing fatigue of individual contacts and increasing mechanical lifespan. Simultaneously, it ensures that the contact pressure of a single circuit is above 40N, far exceeding the contact pressure (25-30)N of conventional 500A products. With the dual-moving-plates in parallel, the contact resistance is low, contact heat generation is low, temperature rise is low, and the current-carrying area is large, thereby meeting the product's 1000A load capacity and low temperature rise requirements.

[0039] Contact material selection: The contact system mainly consists of moving contact piece 13 and stationary contact post 27. The stationary contact post 27 is made of TU1 oxygen-free copper, which is easy to weld to ceramics. The moving contact piece 13 is made of medium-aluminum dispersion-strengthened copper, which has the characteristics of high strength, high hardness, high conductivity, resistance to softening, wear resistance, arc corrosion resistance, and long service life.

[0040] In addition to conducting the load, the contact material must also have a short arcing time under the same conditions. Comparing the arcing times of three commonly used materials under the same conditions—oxygen-free copper, dispersed copper, and second-generation copper—the corresponding arcing times are 2.1ms, 1.7ms, and 1.01ms, respectively. Therefore, dispersed copper is chosen, as its arcing time is only half that of oxygen-free copper.

[0041] Arc extinguishing system design: The fundamental cause of arc ignition is high voltage and high current, especially high voltage. Under normal temperature and humidity, the critical breakdown voltage of air is 200-300V. An inductive load with a current of 1A can generate an arc. The load voltage of this invention is 1000V DC and the load current is 1000A, so the arcing phenomenon is more serious. Therefore, the requirements for the arc extinguishing system are more stringent.

[0042] The performance of the contactor was improved in the following aspects:

[0043] Adding ceramic arc-extinguishing grid design: Four ceramic grid plates 32 and two ceramic grid plates 34 are added to the arc-extinguishing cover 11. The grid plates are designed with a certain distance between them, and are placed on both sides of the joint position between the moving contact plate 13 and the stationary contact post 27. (See...) Figure 2 The arc blown by the arc-extinguishing magnet 33 is introduced into the narrow slit, thereby increasing the arc's trajectory, rapidly cutting off the arc, cooling it, and extinguishing it.

[0044] Arc extinguishing environment: The moving contact piece 13 and the stationary contact post 27 are placed in the sealed space formed by the laser welding of ceramic 6 and flange 15, and flange and liner 20. At the same time, a mixture of hydrogen and nitrogen gas (in a certain proportion) is injected into the sealed space. The contacts are placed in the nitrogen and hydrogen environment, which reduces the conductivity of the medium, increases the arcing conditions, and increases the arcing voltage. At the same time, being placed in the nitrogen and hydrogen environment can also cool the arc, thereby achieving the effect of arc extinguishing.

[0045] Enhanced magnetic blowout arc extinguishing capability and non-polarity design: The arc-extinguishing magnet 33 is placed on the surface connecting the moving contact piece 13 and the stationary contact post 27, and placed in the arc-extinguishing cover 11. One magnet is placed at each end of each stationary contact post 27. (See...) Figure 2 The arc-extinguishing magnet 33 is positioned with its polarity N-to-N, resulting in a higher magnetic field strength than N-to-S. According to the left-hand rule, regardless of whether the load is connected in the correct or reverse direction, the arc generated between the moving contact 13 and the stationary contact post 27 exerts an outward diffusion force. This causes the arc to be rapidly pulled towards the ceramic grid plate 32 and ceramic grid plate 34 under the action of the Lorentz force. (See...) Figure 4 This increases the trajectory of the electric arc, causing it to be quickly cut off, cooled, and eventually extinguished.

[0046] Arc initiation angle design: An arc initiation angle feature is designed on the moving contact piece 13 to initiate the arc. At the same time, the moving contact piece 13 and the stationary contact post 27 are in a semi-contact form to increase the arc extinguishing space and improve the arc extinguishing capability of the product.

[0047] The design features of this invention are: it adopts a dual-path parallel design, but only has one drive coil, which has the characteristics of high dual-path synchronization, small size, strong load capacity, good mechanical performance and low temperature rise.

Claims

1. A high-reliability non-polar high-voltage DC contactor for megawatt-level charging systems, comprising a housing, a magnetic circuit assembly, a dual-parallel contact system, and an arc-extinguishing system, characterized in that: The magnetic circuit assembly is installed at the bottom of the housing via a flange (15), and a busbar (8) is installed at the top of the housing to connect with the external load. The dual-path parallel contact system is located at the top of the housing. The dual-path parallel contact system includes two moving contact pieces (13), a stationary contact post (27), and an auxiliary contact post (35). The two moving contact pieces (13) are linked to the core rod (21) via a core rod (29) and are reset by a return spring (17) and a contact spring (30). The stationary contact post (27) and the auxiliary contact post (35) are brazed in the ceramic (6) and connected to the busbar (8) respectively. The core rod (21) is movably installed inside the magnetic circuit assembly and connected to the iron core (22). The arc extinguishing system is installed inside the flange (15), and the contact point between the moving contact piece (13) and the stationary contact post (27) is placed inside the arc extinguishing system.

2. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: The outer casing includes an outer cover assembly (1) and a cover plate (9). The outer cover assembly (1) is a stepped cylinder. The upper step of the outer cover assembly (1) supports the edge of the flange (15). The middle part of the flange (15) is recessed downward and riveted to the magnetic circuit assembly. The top edge of the arc extinguishing system is supported on the edge of the flange (15). The ceramic (6) is located on the top of the arc extinguishing system. The edge of the ceramic (6) is also fixed with a Kovar connecting piece (12). The lower end of the Kovar connecting piece (12) is filled between the outer cover assembly (1) and the ceramic (6) and the bottom is in contact with the nut (5). The upper end of the Kovar connecting piece (12) is pressed against the edge of the ceramic (6) and the top is in contact with the busbar (8). The cover plate (9) is pressed tightly against the middle of the busbar (8). The four corners of the cover plate (9) are fixed to the outer cover assembly (1) by bolts.

3. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 2, characterized in that: The two ends of the busbar (8) are fixedly mounted with load mounting screws (10) by flange nuts (7).

4. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: The arc extinguishing system includes an arc extinguishing cover (11), the top of which is folded outward and fastened to the edge of the flange (15). The arc extinguishing cover (11) contains ceramic grid plate one (34) and ceramic grid plate two (32). Four sets of ceramic grid plate one (34) and ceramic grid plate two (32) are respectively installed opposite to each other on both sides of the contact point. The arc extinguishing cover (11) is also provided with an arc extinguishing magnet (33), which is arranged with N pole to N pole on both sides of the stationary contact post (27).

5. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 4, characterized in that: The arc-extinguishing hood (11) is filled with a mixture of hydrogen and nitrogen gas.

6. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: Two core rods (29) are installed at both ends of the support assembly, the center of the support assembly is installed at the top of the core rod (21), two strip-shaped moving contact pieces (13) are installed on the two core rods (29) respectively, and the contact spring (30) is installed on the core rod (29) and between the support assembly and the moving contact piece (13).

7. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 6, characterized in that: The support assembly includes a support plate (4) and a support piece (14). The middle part of the support piece (14) is embedded in the middle part of the support plate (4). The support plate (4) and the support piece (14) clamp the middle part of the auxiliary point spring (31). The top of the core rod (21) passes through the support piece (14), the auxiliary point spring (31), and the support plate (4) in sequence and is then fixed by a nut.

8. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: The magnetic circuit assembly includes a magnetic pole (16) and an iron core (22). The top of the magnetic pole (16) is riveted to the flange (15). The iron core (22) is threaded to the bottom of the core rod (21). The iron core (22) is covered with a sleeve (20). The magnetic pole (16) and the iron core (22) are surrounded by a coil frame (19). A coil (18) is wound on the coil frame (19). The outside of the coil (18) is wrapped by an iron yoke (2). The return spring (17) is located between the magnetic pole (16) and the iron core (22).

9. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: The magnetic circuit assembly also includes an energy-saving board (23), which is installed on the outside of the inline package (18).

10. The high-reliability non-polarized high-voltage DC contactor for megawatt-level charging systems as described in claim 1, characterized in that: It also includes an insulating pad (3), which is located between the arc-extinguishing cover (11) and the flange (15).

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