A circuit breaker with excitation protection

Abstract

This invention discloses a circuit breaker with excitation protection, comprising a housing, a moving contact bridge, a stationary contact, and a coil assembly for driving the moving contact bridge to make conductive contact with the stationary contact. An excitation source, a conductor power device, and a conductor are disposed within the housing. The moving contact bridge and the conductor are connected in series and are conductively connected. The moving contact bridge is displaceable relative to the conductor. The stationary contact and the conductor are respectively connected to an external circuit as connection terminals. When a fault current occurs, the moving contact bridge separates from the stationary contact, disconnecting the circuit. Alternatively, the excitation source activates upon receiving a fault current trigger signal, driving the conductor power device to disconnect the conductor, simultaneously causing the moving contact bridge to separate from the stationary contact, disconnecting the circuit. This invention integrates the advantages of circuit breakers and fuses, featuring fewer breaks, lower temperature rise and power consumption, and also enables active protection, making it more intelligent and greatly improving the reliability and effectiveness of short-circuit protection.

Description

Technical Field

[0001] This invention relates to the fields of power distribution systems and electric vehicles, and more particularly to a circuit breaker with improved short-circuit protection capability. Background Technology

[0002] With the rapid development of the new energy industry, DC applications are becoming increasingly widespread, especially in the electric vehicle industry. As people demand longer driving ranges, the capacity of vehicle battery packs is also increasing, and the requirements for fault short-circuit current from both vehicle manufacturers and battery pack manufacturers are becoming increasingly stringent. Currently, there are two main categories of battery pack protection solutions: 1. Relays + fuses; 2. Circuit breakers.

[0003] The relay + fuse solution is relatively common. The relay acts as the circuit's on / off control device, and the fuse, in conjunction with it, provides overload and short-circuit protection. However, this solution has many problems. First, relays cannot interrupt large short-circuit currents; their short-circuit withstand capability and anti-sticking capability are poor. Small-sized relays typically have a breaking capacity below 750V / 2000A, a short-circuit withstand capability of 8kA, and a short-circuit withstand time of 5ms, with sticking occurring frequently. In recent years, relay manufacturers have made considerable efforts to improve short-circuit breaking capacity and resistance to short circuits and sticking, but the improvements have been limited. Second, fuses themselves also have problems, mainly manifested in temperature rise, weak resistance to current surges, and slow operation for low-multiplier short-circuit current protection. Due to their physical characteristics, these are difficult to improve. Meanwhile, matching relays and fuses also troubles major car manufacturers and battery pack manufacturers. When a low short-circuit current occurs, the fuse takes a long time to trip, and the relay cannot break the current, resulting in untimely protection. When a high short-circuit current occurs, although the fuse can trip quickly, the relay cannot withstand such a large short-circuit current before the fuse trips, which will cause the relay contacts to open and arc and explode. Therefore, matching relays and fuses is difficult.

[0004] The principle of this circuit breaker design is to rapidly introduce the electric arc from the opening of the moving and stationary contacts into the arc-extinguishing chamber of the grid plates, thereby extinguishing the arc. To increase breaking capacity, the number of breaks and arc-extinguishing grid plates can be increased, but this cannot be infinitely increased due to limitations in size and operating principle. The advantages of this design are: simple structure, mature and stable operation, high breaking capacity, and strong arc-extinguishing capability. The disadvantages are: a large number of breaks are required for high breaking capacity, resulting in a correspondingly high temperature rise; and adhesion is prone to occur, which, if it happens, will render protection impossible, with potentially disastrous consequences. Summary of the Invention

[0005] The purpose of this invention is to provide a circuit breaker with excitation protection, which, while fulfilling the circuit breaker function, can also provide circuit protection by disconnecting the circuit through excitation protection. It features high breaking capacity, is not prone to sticking, and has a compact structure.

[0006] A circuit breaker with excitation protection includes a housing, a moving contact bridge, a stationary contact, and a coil assembly that drives the moving contact bridge to make conductive contact with the stationary contact. An excitation source, a conductor power device, and a conductor are disposed within the housing. The moving contact bridge and the conductor are connected in series and are conductively connected. The moving contact bridge is displaceable relative to the conductor. The stationary contact and the conductor are respectively connected to an external circuit as connection terminals. When a fault current occurs, the moving contact bridge separates from the stationary contact to disconnect the circuit, or the excitation source actuates upon receiving a fault current trigger signal, driving the conductor power device to disconnect the conductor, and simultaneously the moving contact bridge separates from the stationary contact to disconnect the circuit.

[0007] Preferably, a limiting structure is provided between the conductor power device and the contact surface of the housing; when the conductor power device is driven by an excitation source, the limiting structure can be overcome.

[0008] Preferably, at least one weak break is provided on the conductor, and the conductor power device can disconnect the weak break on the conductor to form a fracture.

[0009] Preferably, one end of the conductor is connected in series with the moving contact bridge via a retractable conductive connector; the other end is conductively connected to a terminal extending outside the housing.

[0010] Preferably, the conductive connector is a wire or a retractable conductive spring.

[0011] Preferably, at least one molten metal is connected in parallel on the conductor, and at least one break point formed by the conductor being disconnected by the conductor power device is located between the two ends of the molten metal, which is inserted into the arc extinguishing device.

[0012] Preferably, an arc-extinguishing device is provided near the break point formed by the conductor disconnection.

[0013] Preferably, the arc-extinguishing device includes an arc-extinguishing chamber filled with an arc-extinguishing medium disposed within the housing, and the molten material passes through the arc-extinguishing chamber; the arc-extinguishing medium is sand, an arc-extinguishing grid, or a combination of both.

[0014] Preferably, an arc-initiating and arc-extinguishing structure is provided around the stationary contact and the moving contact bridge.

[0015] Preferably, an arc-inducing plate is connected to one end of the stationary contact and the moving contact bridge, and an arc-extinguishing structure is provided in the housing on one side of the arc-inducing plate.

[0016] Preferably, the arc-extinguishing structure is a plurality of metal or arc-extinguishing grids arranged side by side.

[0017] By using a circuit breaker in series with a fuse, protection against low short-circuit currents and below is achieved through opening the circuit breaker and extinguishing the arc with an arc-extinguishing grid, while protection against high short-circuit currents relies on the excitation of the fuse. This scheme integrates the advantages of circuit breakers and fuses, featuring fewer circuit breaks, lower temperature rise and power consumption, and can also achieve active protection, making it more intelligent and greatly improving the reliability and effectiveness of short-circuit protection. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the melt and arc-extinguishing chamber structure. Detailed Implementation

[0020] Regarding the above technical solutions, preferred embodiments are now described in detail with reference to the accompanying drawings.

[0021] The circuit breaker with excitation protection of the present invention includes a housing, a moving contact bridge, a stationary contact, a coil assembly, an excitation source, a conductor power unit, a conductor, and a fusible element. (See attached diagram.) Figure 1 .

[0022] The housing 100 is made of insulating material. Inside the housing 100 are a coil assembly 101, a moving contact bridge 103, and a stationary contact 104. When energized, the coil assembly 101 drives the moving contact bridge 103 to move within the housing and make conductive contact with the stationary contact. The structure and positional relationship between the coil assembly, the moving contact bridge, and the stationary contact are the same as in a circuit breaker and are existing technology, so they will not be described further here. An arc-extinguishing structure for driving the arc, igniting the arc, and extinguishing the arc is provided around the moving contact bridge and the stationary contact. The driving arc is achieved by magnetic blowing using a magnetic field generated by its own structure or an externally provided magnetic field, or by air blowing generated by the arc ablating the insulating material. An arc-igniting plate 105 is fixedly provided, extending beyond one end of the moving contact bridge and the stationary contact. The arc-igniting plate is flared outwards from the moving and stationary contacts. An arc-extinguishing structure 102 is provided on the outer side of the other end of the arc-igniting plate 105. The arc-extinguishing structure consists of multiple metal or arc-extinguishing grids arranged side-by-side. When the moving contact bridge separates from the stationary contact, the electric arc generated is driven by the magnetic field generated by its own structure and enters the arc extinguishing structure through the arc-initiating plate to extinguish the arc.

[0023] A conductor 203, which is a long, flat plate structure, is fixedly installed inside the housing at the other end of the moving contact bridge. A conductive connector 206 is electrically and fixedly connected to the end of the conductor 203 adjacent to the moving contact bridge. Both ends of the conductive connector are fixedly connected to the moving contact bridge and the conductor, respectively. A terminal 208 is electrically connected to the other end of the conductor, extending outside the housing for connection to an external circuit. The conductive connector is a conductive copper stranded wire, and its length must be sufficiently long so that the copper stranded wire does not affect the displacement of the moving contact bridge or the mechanical disconnection of the conductor when the moving contact bridge moves. The conductive connector can also be a stretchable elastic element, such as a corrugated, compressible conductive spring. When the moving contact bridge displaces, the conductive connector 206 can be stretched or shortened.

[0024] An excitation source 201 and a conductor power device 202 are sequentially installed inside one side of the housing of conductor 203. The excitation source 201 is a gas generator that can ignite upon receiving a trigger signal, releasing a large amount of high-pressure gas as the driving force for the conductor power device. The conductor power device is a piston. A sealed cavity (not shown) exists between the excitation source 201 and the conductor power device 202. The conductor power device is in sealed contact with the housing to ensure sufficient driving force is provided. This sealing contact can be achieved through a sealing ring or an interference fit. A limiting structure (not shown) is provided on the contact surface between the conductor power device and the housing to limit the movement of the conductor power device. The limiting structure can be a slot and a protrusion that engages in the slot. The slot is located on the housing, and the protrusion is located on the conductor power device. Alternatively, an interference fit can be used to achieve contact sealing and initial position limiting. A weak point 203a is provided on conductor 203. This weak point is a structure designed to reduce the mechanical strength of the conductor or concentrate mechanical stress, such as a groove extending through the conductor's width or a variable cross-section structure. The conductor power device is positioned directly opposite the weak point of the conductor, disconnecting the conductor at the weak point and forming at least one break in the conductor.

[0025] An arc-extinguishing device is installed near the fracture site on conductor 203, or an arc-extinguishing device is connected in parallel on the conductor. When the arc-extinguishing device is located near the conductor fracture site, an arc-extinguishing grid structure is installed near the fracture site to extinguish the arc generated at the conductor fracture. The arc-extinguishing grid structure and the conductor fracture site have cavities to accommodate the broken portion of the conductor after it is broken. When the arc-extinguishing device is installed in parallel on the conductor, the arc-extinguishing device includes a melt 204 connected in parallel on the conductor. (See [reference]) Figure 1 and Figure 2 The molten material 204 passes through the arc-extinguishing chamber 205 located within the shell. The arc-extinguishing chamber 205 is filled with an arc-extinguishing medium, which may be sand, arc-extinguishing grid sheets, or a combination of both. The molten material 204 is connected to the conductor by welding or screws. A cavity 207 is provided between the conductor and the arc-extinguishing chamber to accommodate the conductor breakage section after the conductor is disconnected.

[0026] The circuit breaker with excitation protection is equipped with a circuit board (not shown) as a control device. The circuit board has functions such as energy saving, detection and hierarchical control. Energy saving can be achieved through PWM control or dual coils. Hall devices on the circuit board detect the current on the conductor and feed it back to the circuit board or the BMS system outside the product of this invention to perform hierarchical control to achieve protection. When the current is less than the set threshold, the control coil assembly is de-energized, so that the moving contact bridge is separated from the stationary contact to disconnect the circuit. At this time, the generated arc is relatively small and can be extinguished by the arc extinguishing structure around the moving contact and the stationary contact. When the current is greater than or equal to the set threshold, a trigger signal is sent to the excitation source, and the excitation source drives the conductor power device to disconnect the conductor; or the response can be delayed.

[0027] The working process of the circuit breaker with excitation protection of the present invention:

[0028] Connect the stationary contact and terminals of the circuit breaker with excitation protection to the circuit respectively. Under normal operating conditions, when the coil assembly 101 is energized, the moving contact bridge 103 closes with the stationary contact 104, and the main circuit is connected; when the coil assembly is de-energized, the moving contact bridge 103 separates from the stationary contact 104, and the main circuit is disconnected. When disconnected, the arc is blown into the arc-extinguishing grid 102 by magnetic blowing to extinguish the arc. When the circuit board detects a short-circuit current, if the short-circuit current is less than 1500A, the circuit board cuts off the power supply to the coil assembly 101, and the moving contact bridge 103 separates from the stationary contact 104 to cut off the current. If the short-circuit current is greater than or equal to 1500A, the circuit board sends a trigger signal to the excitation source 201 and cuts off the power supply to the coil 101 at the same time. After receiving the trigger signal, the excitation source ignites and explodes, generating a large amount of high-pressure gas to drive the conductor power device 202 to overcome the displacement of the limiting structure and quickly break the conductor 203 to form a break on the conductor. Since most of the short-circuit current is guided on the fusible element 204, the fusible element completes the short-circuit protection through current limiting and rapid melting. The arc generated when the fusible element melts is extinguished by the arc-extinguishing medium. The whole process is completed within 3ms. Immediately afterwards, the moving contact bridge 103 and the stationary contact 104 also disconnect.

[0029] The circuit breaker with excitation protection of the present invention can achieve breaking capacity over a wide short-circuit current range, thereby improving both breaking capacity and arc extinguishing capacity.

Claims

1. A circuit breaker with excitation protection, comprising a housing, a moving contact bridge, a stationary contact, and a coil assembly for driving the moving contact bridge into conductive contact with the stationary contact; characterized in that, The housing contains an excitation source, a conductor power device, a conductor, and a control circuit board. The moving contact bridge is connected in series with the conductor and is electrically conductive. The moving contact bridge can be displaced relative to the conductor. The stationary contact and the conductor are respectively connected to an external circuit as connection terminals. The circuit board controls the on / off state of the coil assembly and the operation of the excitation source. When the fault current is small, the moving contact bridge separates from the stationary contact to disconnect the circuit. When the fault current is large, the excitation source operates according to the received fault current trigger signal, driving the conductor power device to disconnect the conductor, and at the same time, the moving contact bridge separates from the stationary contact to disconnect the circuit.

2. The circuit breaker with excitation protection according to claim 1, characterized in that, A limiting structure is provided between the conductor power device and the shell contact surface; when the conductor power device is driven by an excitation source, it can overcome the limitation of the limiting structure.

3. The circuit breaker with excitation protection according to claim 1, characterized in that, At least one weak point is provided on the conductor, and the conductor power device can disconnect the weak point on the conductor to form a break.

4. The circuit breaker with excitation protection according to claim 1, characterized in that, One end of the conductor is connected in series with the moving contact bridge via a retractable conductive connector; the other end is conductively connected to a terminal extending outside the housing.

5. The circuit breaker with excitation protection according to claim 4, characterized in that, The conductive connector is a wire or a retractable conductive spring.

6. The circuit breaker with excitation protection according to any one of claims 1 to 5, characterized in that, At least one molten material is connected in parallel on the conductor, and at least one break point formed by the conductor being disconnected by the conductor power device is located between the two ends of the molten material, which is inserted into the arc extinguishing device.

7. The circuit breaker with excitation protection according to any one of claims 1 to 5, characterized in that, An arc-extinguishing device is installed near the break point formed by the conductor disconnection.

8. The circuit breaker with excitation protection according to claim 6, characterized in that, The arc-extinguishing device includes an arc-extinguishing chamber filled with an arc-extinguishing medium inside the housing, and the molten material passes through the arc-extinguishing chamber; the arc-extinguishing medium is sand, an arc-extinguishing grid, or a combination of both.

9. The circuit breaker with excitation protection according to claim 1, characterized in that, Arc-initiating and arc-extinguishing structures are provided around the stationary contact and the moving contact bridge.

10. The circuit breaker with excitation protection according to claim 9, characterized in that, An arc-initiating plate is connected to one end of the stationary contact and the moving contact bridge to form an arc-initiating structure, and an arc-extinguishing structure is provided in the housing on one side of the arc-initiating plate.

11. The circuit breaker with excitation protection according to claim 9, characterized in that, The arc-extinguishing structure consists of multiple metal or arc-extinguishing grids arranged side by side.

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