A dual-mode cooled solid state circuit breaker and a thermal management method thereof

Abstract

The application discloses a dual-mode cooling solid-state circuit breaker and a thermal management method thereof, and belongs to the field of power semiconductor device thermal management. The solid-state circuit breaker comprises a power semiconductor die, a manifold micro-channel radiator, a boiling phase change cooling cavity, an electronic fluorination liquid, a condenser, an electromagnetic valve, a speed regulating pump and a driving and control system. The application identifies the working condition of the solid-state circuit breaker by collecting the on-state voltage drop of the power semiconductor chip, and the manifold micro-channel radiator alone bears the on-state loss heat dissipation in the steady state condition. In the overcurrent condition, local overheating triggers the boiling phase change of the electronic fluorination liquid, the condenser is started at the same time, and the pump speed is increased, the boiling reinforcement and heat capacity peak shaving effect of the molybdenum copper thermal expansion block are combined, and the transient thermal shock is quickly inhibited. The method takes into account the long-term steady-state operation and transient overcurrent heat dissipation demand, and has an important role in prolonging the service life of the chip, improving the thermal reliability and operation energy efficiency of the solid-state circuit breaker in the multi-working condition.

Description

A dual-mode cooled solid-state circuit breaker and its thermal management method Technical Field

[0001] This invention relates to the field of thermal management technology for power semiconductor devices, and specifically to a dual-mode cooled solid-state circuit breaker and its thermal management method. Background Technology

[0002] Solid-state circuit breakers (SSDs) have gained widespread attention and application in DC power distribution systems due to their advantages such as short response time, no moving parts, and no electric arc. Si or SiC-based IGBTs / MOSFETs / JFETs, with their low conduction losses and high junction temperature tolerance, have become the preferred power chips for medium- and low-voltage DC SSDs. In terms of thermal management, SSDs need to continuously dissipate the steady-state conduction losses of the power semiconductor chip during normal closing. When a short-circuit fault occurs, the circuit breaker typically breaks the circuit within microseconds, resulting in a relatively limited chip temperature rise. However, when overcurrent conditions occur (typically 2-3 times the rated current), the SSD needs to remain closed for several seconds to tens of seconds. During this time, the transient conduction losses of the power semiconductor chip increase sharply, posing a severe challenge to the heat dissipation system.

[0003] Currently, various advanced heat dissipation technologies have been proposed for the thermal management of power semiconductor chips, such as heat pipe cooling, microchannel liquid cooling, and jet impingement cooling. These methods can, to some extent, address the high heat flux density heat dissipation problem caused by the miniaturization of chip size. However, a single cooling method often fails to meet the differentiated thermal management needs of solid-state circuit breakers under steady-state and transient conditions: if the heat dissipation system is designed only based on rated steady-state losses, the chip junction temperature will rise rapidly under overcurrent conditions, posing a risk of overheating and damage; if the heat dissipation capacity is designed according to overcurrent conditions, the heat dissipation capacity will be excessive during most steady-state operation, resulting in wasted resources. Furthermore, even if the cooling power is increased in real time through overcurrent monitoring, conventional liquid cooling systems, limited by response speeds in the hundreds of milliseconds to seconds, still cannot effectively suppress the thermal shock experienced by the chip during transient overcurrent.

[0004] To improve the short-term overload capacity of power modules, existing technologies often use solid-solid or solid-liquid phase change materials to encapsulate the modules, absorbing the heat generated by overcurrent through the phase change process. However, this method suffers from problems such as slow response speed, difficulty in continuously dissipating heat, and insufficient thermal recovery capability when faced with repeated overcurrent.

[0005] In summary, effectively managing the continuous conduction loss of the chip under steady-state conditions and rapidly suppressing junction temperature rise during transient overcurrent has become a key technical challenge to ensure the reliable operation of solid-state circuit breakers under multiple operating conditions. Summary of the Invention

[0006] This invention addresses the problem that a single cooling method cannot simultaneously meet the thermal management requirements of solid-state circuit breakers under both steady-state operation and transient overcurrent conditions. It proposes a dual-mode cooling solid-state circuit breaker and its thermal management method. This invention enables reliable cooling of the solid-state circuit breaker under high heat flux density conditions during steady-state operation and rapid suppression of transient thermal shocks under overcurrent conditions.

[0007] Therefore, the present invention provides the following technical solution:

[0008] The present invention first provides a dual-mode cooled solid-state circuit breaker. The main structure of the solid-state circuit breaker includes a power semiconductor die, a copper-clad ceramic plate, a molybdenum-copper heat expansion block, a copper conductive strip, a power terminal, a manifold microchannel heat sink, a boiling phase change cooling chamber, a condenser, a speed regulating pump, and a drive and control system.

[0009] The bottom of the boiling phase change cooling chamber is fixedly connected and sealed to the upper surface of the manifold microchannel heat sink, and the top is fixedly connected and sealed to the lower surface of the condenser. The boiling phase change cooling chamber is filled with an electronic fluorinated liquid with a boiling point matching the transient heating characteristics of the power semiconductor die. The power semiconductor die, copper-clad ceramic plate, molybdenum-copper heat expansion block, and copper conductive strip are all placed in the electronic fluorinated liquid inside the boiling phase change cooling chamber. The bottom of the power semiconductor die is connected to the copper-clad ceramic plate to realize the circuit breaker closing / opening function. The bottom of the copper-clad ceramic plate is fixedly connected to the upper surface of the manifold microchannel heat sink. The top of the power semiconductor die is connected to the copper conductive strip through the molybdenum-copper heat expansion block.

[0010] A speed-regulating pump is installed on the main cooling water channel to control the pumping speed of the fluid in the main channel. The main channel connects two parallel cooling water branches. The manifold microchannel radiator and condenser are respectively installed on the two cooling water branches.

[0011] The drive and control system acquires the on-state voltage drop of the power semiconductor die in real time, identifies the working status of the power semiconductor die, and determines the closing / opening logic control and cooling mode switching of the solid-state circuit breaker.

[0012] According to a preferred embodiment of the present invention, the copper-clad ceramic plate is composed of three layers: a top copper clad layer, an AlN insulating ceramic sheet, and a bottom copper clad layer. The power semiconductor die is sintered on the top copper clad layer to realize the circuit breaker's closing / breaking function. The molybdenum-copper heat expansion block is engraved with heat-enhancing microstructures around its perimeter to expand the heat dissipation area and provide heat capacity for the power semiconductor die. Its bottom is sintered with the source electrode of the power semiconductor die, and its top is welded or sintered with the copper conductive strip to form an electrical circuit. Power terminals are led out from the top copper clad layer of the copper-clad ceramic plate for connection to the wiring outside the boiling phase change cooling cavity.

[0013] According to a preferred embodiment of the present invention, the manifold microchannel radiator includes two components: a manifold and a microchannel. It is used to dissipate conduction losses under steady-state conditions of the solid-state circuit breaker and to suppress boiling within the microchannel by increasing the cooling water flow rate under overcurrent conditions. The top of the microchannel is sintered with the bottom of the copper-clad ceramic plate, and the bottom of the microchannel is sintered with the manifold. The manifold is installed on one of the cooling water branches and is equipped with a manifold cooling water inlet pipe and a manifold cooling water outlet pipe for connecting to the cooling water branch. Temperature sensors and differential pressure sensors are installed at both the inlet and outlet of the manifold, and check valves are also provided.

[0014] According to a preferred embodiment of the present invention, the drive and control system acquires the on-state voltage drop of the power semiconductor die in real time, identifies steady-state, transient, and short-circuit conditions based on a set threshold, and determines the closing / opening logic control of the solid-state circuit breaker and the switching of the cooling mode based on the working state; at the same time, it acquires the inlet and outlet temperatures and pressure difference of the manifold microchannel radiator cooling water and the pressure of the boiling phase change cooling chamber for safety limiting.

[0015] The present invention also provides a thermal management method for a solid-state circuit breaker based on the aforementioned dual-mode cooling, comprising:

[0016] During normal operation, the on-state voltage drop of the power semiconductor die of the solid-state circuit breaker is low. At this time, the drive and control system judges that the solid-state circuit breaker is in steady-state condition and is in normal cooling mode. That is, the manifold microchannel heat sink is working normally, the speed pump is running at the rated preset pump speed, the solenoid valve is kept closed, and the boiling phase change cooling chamber and condenser are not working. The temperature of the power semiconductor die under steady-state condition is designed to be 80~90℃.

[0017] When the on-state voltage drop of the power semiconductor die exceeds the steady-state operating threshold but is below the short-circuit fault threshold, the drive and control system determines that the solid-state circuit breaker is in an overcurrent condition and switches to transient cooling mode. Under the overcurrent condition, the power consumption of the power semiconductor die increases sharply, and the chip temperature gradually rises. When the local temperature exceeds the boiling point of the electronic fluorinated liquid by a certain superheat, the electronic fluorinated liquid is automatically triggered to boil. In transient cooling mode, the solenoid valve is opened to start the condenser to cool the boiling phase-change gaseous electronic fluorinated liquid, and the gaseous working fluid is condensed and returned by the condenser. At the same time, the preset pump speed of the cooling water speed regulating pump is increased to increase the cooling water flow in the manifold, enhance the heat dissipation capacity of the manifold microchannel radiator, and prevent the cooling water in the microchannel from boiling and blocking the channel, thus ensuring the cooling effect. When the overcurrent condition ends and the on-state voltage drop drops below the steady-state operating threshold, the solenoid valve is closed, and the pump speed of the speed regulating pump is reduced to the rated value, and the solid-state circuit breaker returns to the normal cooling mode.

[0018] When the on-state voltage drop of the power semiconductor die exceeds the short-circuit fault threshold, the solid-state circuit breaker operates in short-circuit condition. The drive and control system determines that a short-circuit fault has occurred in the line where the solid-state circuit breaker is located and controls the solid-state circuit breaker to operate to disconnect the faulty line. At the same time, the solid-state circuit breaker switches to transient cooling mode. After the solid-state circuit breaker disconnects the fault, the drive and control system attempts to reclose after a set time. If the reclosing is successful, the solid-state circuit breaker returns to normal cooling mode after the on-state voltage drop of the power semiconductor die drops below the steady-state operating threshold. If the reclosing fails, the drive and control system stops attempting to reclose, and closes the solenoid valve after the pressure of the boiling phase change cooling chamber drops to normal pressure. After the water temperature of the manifold cooling water outlet drops to room temperature, the speed regulating pump is turned off, and the solid-state circuit breaker enters standby mode to wait for line maintenance.

[0019] The present invention has the following beneficial effects:

[0020] (1) The present invention uses the bottom manifold microchannel heat sink to handle the heat dissipation of the steady-state conduction loss of the solid circuit breaker, and the top boiling phase change cavity to trigger two-phase boiling at a superheat of 10~20℃ under the overcurrent condition of the solid circuit breaker. Combined with the boiling enhancement and heat capacity peak reduction effect of the molybdenum-copper thermal expansion block, it takes into account both long-term operation and transient safety margin. In addition, the two-phase boiling is directly triggered by local overheating, and the response speed under the overcurrent condition is fast.

[0021] (2) This invention identifies the operating conditions of the solid-state circuit breaker by collecting parameters such as the on-state voltage drop of the power semiconductor chip, the inlet and outlet water temperature and pressure difference, and the cavity pressure, and realizes the efficient coordination of the dual cooling modes of the solid-state circuit breaker. Under the overcurrent condition, the control system simultaneously opens the condenser cooling water branch and increases the pump speed. The vapor phase heat is quickly dissipated and condensed back. After the overcurrent is relieved, it can quickly recover to the steady state temperature and support multiple overcurrent thermal shocks, avoiding the heat accumulation and difficulty in quick reset of the PCM heat storage type scheme.

[0022] (3) In the overcurrent mode, the present invention reduces the cavity pressure by increasing the flow rate of the manifold microchannel and linking it with the condenser, thereby suppressing the evolution of local nucleation boiling into film boiling in the microchannel; the branch check valve and differential pressure / temperature monitoring avoid backflow and steam blockage risks, maintain single-phase flow and controllable pressure drop and unobstructed channels under high heat flux density in the overcurrent condition, and improve the reliability of the solid circuit breaker.

[0023] (4) Under normal operating conditions, only the manifold microchannel radiator works, the condenser branch is closed, and the pump runs at the rated speed. This avoids long-term "overcooling" for the overcurrent limit. Only during transient overcurrent conditions is the pump speed increased and the condenser branch solenoid valve opened. The average energy consumption is significantly lower than that of a single cooling mode scheme designed with redundancy for overcurrent conditions. Attached Figure Description

[0024] Figure 1 is a structural diagram of an embodiment of the dual-mode cooling solid-state circuit breaker of the present invention;

[0025] Figure 2 is a schematic diagram of the structure of the molybdenum-copper heat expansion block and its enhanced heat exchange microstructure according to an embodiment of the present invention.

[0026] Figure 3 is a schematic diagram of the common source connection method used in solid-state circuit breakers;

[0027] Figure 4 is a schematic diagram of the "Z"-shaped manifold and microchannel used in the manifold microchannel radiator;

[0028] Figure 5 is a schematic flowchart of the thermal management method for the dual-mode cooling solid-state circuit breaker of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 is a structural diagram of an embodiment of the dual-mode cooling solid-state circuit breaker of the present invention. The solid-state circuit breaker of the present invention mainly includes: a power semiconductor die 1, a copper-clad ceramic plate 2, a molybdenum-copper heat spreader 7, a copper conductive strip 8, a power terminal 6, a manifold microchannel heat sink 3, a boiling phase change cooling chamber 4, an electronic fluorinated liquid 5, a sealing plug 9, a condenser 10, a manifold cooling water inlet pipe 11, a manifold cooling water outlet pipe 12, a condenser cooling water inlet pipe 13, a condenser cooling water outlet pipe 14, a solenoid valve 15, a speed regulating pump 16, and a drive and control system 17. The power semiconductor die 1 can be a die of a Si or SiC-based IGBT / MOSFET / JFET power semiconductor device. The choice of the power semiconductor die 1 does not change the thermal management method of the present invention or the connection method of other components inside the solid-state circuit breaker. Typically, but not limitingly, in the following embodiments of the present invention, a SiC MOSFET die is used as an example to describe the present invention.

[0031] The dual-mode cooled solid-state circuit breaker of this invention is connected in series with an external circuit or the protected equipment via power terminal 6 to perform circuit breaker closing / opening functions. Since the solid-state circuit breaker is connected in series with the protected object, when the power semiconductor die is conducting, current can flow smoothly, and the line is connected, equivalent to the solid-state circuit breaker closing. When a short-circuit fault occurs in the line, a turn-off signal is sent to the power semiconductor die, causing it to switch from "conducting" to "turning off," thereby cutting off the fault current, protecting downstream equipment from damage, and preventing the fault from escalating, equivalent to the solid-state circuit breaker opening. Specifically, in an optional embodiment of this invention, when closing is required, the drive and control system 17 sends a conduction signal, applying a +18V drive voltage between the gate and source of the power semiconductor die 1; when opening is required, the drive and control system sends a turn-off signal, applying a -2V drive voltage between the gate and source of the power semiconductor die.

[0032] In one specific embodiment of the present invention, the copper-clad ceramic plate 2 is composed of three layers: a top copper-clad plate 2-1, an AlN insulating ceramic sheet 2-2, and a bottom copper-clad plate 2-3. The thickness of the top and bottom copper clad plates is 0.3 mm, and the thickness of the AlN insulating ceramic sheet is 0.38 mm. The SiC MOSFET power semiconductor die 1 is sintered on top of the top copper-clad plate 2-1 to realize the circuit breaker's closing / breaking function. The molybdenum-copper heat expansion block 7 has a size of 4×3×2 mm and is engraved with heat-enhancing microstructures around its perimeter to expand the heat dissipation area and provide heat capacity for the power semiconductor. In this embodiment, the heat-enhancing microstructures adopt an array of columnar microstructures with a side length of 30 μm, a height of 60 μm, and a spacing of 60 μm. μm, as shown in Figure 2; the bottom of the molybdenum copper heat expansion block 7 is sintered with the source electrode of the power semiconductor bare die 1, and the top is welded or sintered with the copper conductive strip 8 to form an electrical circuit. In this embodiment, the solid-state circuit breaker adopts a common source connection method, which is applicable to both AC and DC operating conditions, as shown in Figure 3; the power terminal 6 is led out from the copper-plated part 2-1 on the top of the copper-plated ceramic plate and is used to connect with external lines.

[0033] In a specific embodiment of the present invention, the manifold microchannel radiator 3 includes two components: a manifold 3-1 and a microchannel 3-2. The microchannel structure has a large specific surface area, so the contact area between the coolant and the heat source is large, which effectively enhances the heat transfer intensity. It can remove heat per unit area that is much greater than that of macroscopic channels, thereby meeting the premise of "designing heat dissipation according to steady-state operating conditions". This invention uses water as a cooling medium and leverages the large specific surface area structure of microchannels to address the high heat flux density heat dissipation requirements of power semiconductor chips. The microchannel 3-2 has a slot width of 200 μm and an adjacent slot spacing of 400 μm. The manifold 3-1 adopts a "Z"-shaped manifold with a wall thickness of 0.56 mm, as shown in Figure 4. The manifold microchannel heat sink 3 is used to dissipate conduction losses under steady-state conditions of the solid-state circuit breaker and to suppress boiling within the microchannel by increasing the cooling water flow rate under overcurrent conditions. The top of the microchannel 3-2 is sintered with the bottom of the copper-clad ceramic plate with copper 2-3, and the bottom of the microchannel 3-2 is sintered with the manifold 3-1. The manifold 3-1 is equipped with a manifold cooling water inlet pipe 11 and a manifold cooling water outlet pipe 12. Temperature sensors 18 and differential pressure sensors 19 are configured at the manifold inlet / outlet ends (on the manifold cooling water inlet pipe 11 and the manifold cooling water outlet pipe 12), and check valves are also provided.

[0034] In one specific embodiment of the present invention, the boiling phase change cooling chamber 4 is placed on top of the manifold microchannel radiator 3. The chamber is filled with electronic fluorinated liquid 5 whose boiling point matches the transient heating characteristics of the bare die, for handling the thermal shock under transient overcurrent conditions of the solid-state circuit breaker. The bottom flange of the boiling phase change cooling chamber 4 has an O-ring groove and is fitted with an O-ring on the circumferential mounting contact surface with the manifold microchannel radiator 3 to prevent leakage of electronic fluorinated liquid 5. The side wall of the boiling phase change cooling chamber 4 is provided with a liquid inlet 20 and a liquid outlet 21. The top of the chamber is equipped with a sealing plug 9 and a pressure gauge 22, wherein the sealing plug 9 is used to lead out a signal line and the pressure gauge 22 is used for pressure monitoring inside the chamber.

[0035] The electronic fluorinated liquid 5 used in this invention is an insulating liquid, and preferred materials include perfluorononene epoxide, perfluoropolyether, and fluoropropylamine. If the recommended operating temperature of the chip does not exceed 150°C, an electronic fluorinated liquid with a boiling point of 120-140°C at atmospheric pressure is preferred; if the recommended operating temperature of the chip does not exceed 175°C, an electronic fluorinated liquid with a boiling point of 145-165°C at atmospheric pressure is preferred, and a high latent heat of vaporization is desirable. In this embodiment, perfluorononene epoxide is selected as the electronic fluorinated liquid, with a boiling point of 124.4°C at atmospheric pressure.

[0036] It should be noted that at least a portion of the upper part of the boiling phase change cooling chamber 4 is reserved without being filled with electronic fluorinated liquid 5. Preferably, the filling height of electronic fluorinated liquid 5 is two-thirds of the height of the boiling phase change cooling chamber 4.

[0037] In a specific embodiment of the present invention, the condenser 10 is installed on the top of the boiling phase change cooling chamber 4 to cool the gaseous electronic fluorinated liquid after boiling phase change. The condenser 10 completely covers the top of the boiling phase change cooling chamber 4. The contact surface between the top flange of the boiling phase change cooling chamber 4 and the condenser 10 is provided with an O-ring groove and equipped with an O-ring to ensure the airtightness of the chamber. The condenser 10 is equipped with a condenser cooling water inlet pipe 13 and a condenser cooling water outlet pipe 14, as shown in Figure 1. The condenser 10 and the manifold microchannel radiator 3 share the same cooling water source but have independent branches (the two are connected in parallel by pipelines). A solenoid valve 15 and a check valve are provided at the inlet of the condenser cooling water inlet pipe 13 to control the flow of water in the condenser 10. The speed regulating pump 16 is installed at the cooling water inlet of the main water circuit (i.e., the speed regulating pump 16 can synchronously adjust the cooling water flow rate in the two branches). The speed regulating pump 16 operates at the rated preset pump speed under steady-state conditions and at the overcurrent preset pump speed under transient conditions (the overcurrent preset pump speed is greater than the rated preset pump speed).

[0038] In a specific embodiment of the present invention, the drive and control system 17 collects the on-state voltage drop of the power semiconductor die 1 in real time, identifies steady-state, transient, and short-circuit conditions according to the set threshold, and determines the closing / opening logic control of the solid-state circuit breaker and the switching of the cooling mode according to the working state; at the same time, it collects the inlet / outlet temperature and pressure difference of the cooling water of the manifold microchannel radiator 3 and the pressure of the boiling phase change cooling chamber 4 for safety limiting.

[0039] The thermal management method for a solid-state circuit breaker with dual-mode cooling based on the present invention is shown in Figure 5, including:

[0040] After the solid-state circuit breaker starts, it first checks whether the pressure of the boiling phase change chamber is normal. If abnormal, it performs a shutdown for maintenance. If normal, it starts the speed-regulating pump to the rated preset pump speed and checks the differential pressure and water temperature. If abnormal, it also enters the shutdown for maintenance process. If everything is normal, the system closes and enters the operating state. During operation, the drive and control system 17 collects the on-state voltage drop V of the power semiconductor die 1 in real time and sets the overcurrent threshold V1 and the short-circuit threshold V2. Based on the collected on-state voltage drop V values, it classifies three operating conditions and corresponding cooling strategies. In this embodiment, V1 is set as the on-state voltage drop value corresponding to 1.25 times the rated current of the power semiconductor chip at the steady-state operating temperature, and V2 is set as the on-state voltage drop value corresponding to 4 times the rated current of the power semiconductor chip at the normal operating temperature.

[0041] If V < V1, the on-state voltage drop of the power semiconductor die 1 falls below the overcurrent threshold. The drive and control system 17 determines that the solid-state circuit breaker is in steady-state operation. The solid-state circuit breaker adopts conventional cooling mode, i.e., the solenoid valve 15 remains closed, the boiling phase change cooling chamber 4 and the condenser 10 do not work; the speed regulating pump 16 operates at the rated preset pump speed, and the manifold microchannel heat sink 3 operates at the rated cooling power. Under steady-state conditions, the temperature of the power semiconductor die 1 is typically designed to be around 80~90℃.

[0042] If V2 ≤ V < V1, the on-state voltage drop of the power semiconductor die 1 exceeds the overcurrent threshold but is below the short-circuit threshold. The drive and control system 17 determines that the solid-state circuit breaker is in an overcurrent condition and switches to transient cooling mode. Under overcurrent conditions, the power consumption of the power semiconductor die 1 increases sharply, and the chip temperature gradually rises. When the local temperature exceeds the boiling point of the electronic fluorinated liquid 5 by a certain superheat (the superheat is usually designed to be 10~20℃), the electronic fluorinated liquid 5 is automatically triggered to boil. In addition, in transient cooling mode, the solenoid valve 15 is opened to start the condenser 10 to cool the boiling phase-change gaseous electronic fluorinated liquid. The gaseous working fluid is condensed and returned by the condenser 10. At the same time, the preset pump speed of the cooling water speed regulating pump 16 is increased to increase the cooling water flow in the manifold 3-1, increase the cooling condition of the manifold microchannel radiator 3, and prevent the cooling water in the microchannel 3-2 from boiling and blocking the channel, thus ensuring the cooling effect. When the overcurrent condition ends and the on-state voltage drop drops below the steady-state operating threshold, the solenoid valve 15 is closed and the pump speed of the speed regulating pump 16 is reduced to the rated value, and the solid-state circuit breaker returns to the normal cooling mode. If the overcurrent condition continues to occur in extreme cases and the chip temperature gradually rises until the on-state voltage drop exceeds the short-circuit condition threshold, then it is handled as a short-circuit condition.

[0043] If V ≥ V2, the on-state voltage drop of the power semiconductor die 1 exceeds the short-circuit fault threshold, and the solid-state circuit breaker operates in short-circuit condition. The drive and control system 17 determines that the line where the solid-state circuit breaker is located has been in overcurrent condition for a long time or has experienced a short-circuit fault, and controls the solid-state circuit breaker to operate to disconnect the faulty line. At the same time, the solid-state circuit breaker switches to transient cooling mode. Since the power semiconductor chip 1 is turned off, the on-state voltage drop acquisition is blocked. The drive and control system 17 attempts to reclose the circuit breaker 300ms after the solid-state circuit breaker disconnects the fault. If the reclosing is successful, the solid-state circuit breaker returns to normal cooling mode after the on-state voltage drop of the power semiconductor die 1 drops below the steady-state operating threshold. If the reclosing fails, the drive and control system stops attempting to reclose the circuit. After the pressure of the boiling phase change cooling chamber 4 drops to normal pressure, the solenoid valve 15 is closed. After the water temperature of the manifold cooling water outlet pipe 12 drops to room temperature, the speed regulating pump 16 is closed. The solid-state circuit breaker enters standby mode, waiting for line maintenance.

[0044] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A solid-state circuit breaker with dual-mode cooling, characterized in that, The solid-state circuit breaker's main structure includes a power semiconductor die (1), a copper-clad ceramic plate (2), a molybdenum-copper heat expansion block (7), a copper conductive strip (8), a power terminal (6), a manifold microchannel heat sink (3), a boiling phase change cooling chamber (4), a condenser (10), a speed-regulating pump (16), and a drive and control system (17). The bottom of the boiling phase change cooling chamber (4) is fixedly connected and sealed to the upper surface of the manifold microchannel heat sink, and the top is fixedly connected and sealed to the lower surface of the condenser (10). The boiling phase change cooling chamber is filled with boiling point and power semiconductor... The electronic fluorinated liquid (5) is an insulating liquid with a normal boiling point of 120~140℃ or 145~165℃, matching the transient heating characteristics of the bare die. The power semiconductor bare die, copper-clad ceramic plate, molybdenum-copper heat expansion block, and copper conductive strip are all placed in the electronic fluorinated liquid inside the boiling phase change cooling cavity (4). The bottom of the power semiconductor bare die is connected to the copper-clad ceramic plate, and the bottom of the copper-clad ceramic plate is fixedly connected to the upper surface of the manifold microchannel heat sink. The top of the power semiconductor bare die is connected to the copper conductive strip through the molybdenum-copper heat expansion block. The speed pump (16) The manifold microchannel radiator (3) and condenser (10) are installed on the main cooling water channel to control the pumping speed of the fluid in the main channel. The main channel connects two parallel cooling water branches. The manifold microchannel radiator (3) and condenser (10) are respectively installed on the two cooling water branches. The manifold microchannel radiator (3) includes two components: manifold (3-1) and microchannel (3-2). It is used to dissipate the conduction loss under the steady-state condition of the solid circuit breaker and to suppress boiling in the microchannel by increasing the cooling water flow rate under the overcurrent condition. The top of the microchannel (3-2) and the bottom of the copper-clad ceramic plate are sintered with copper (2-3). The bottom of the microchannel (3-2) is sintered with the manifold (3-1); the manifold (3-1) is set on one of the cooling water branches, and it is equipped with a manifold cooling water inlet pipe (11) and a manifold cooling water outlet pipe (12) for connecting the cooling water branches. Temperature sensors (18) and differential pressure sensors (19) are configured at the inlet and outlet of the manifold, and check valves are set; the drive and control system collects the on-state voltage drop of the power semiconductor die in real time, identifies the working state of the power semiconductor die, and determines the closing / opening logic control of the solid-state circuit breaker and the cooling mode switching.

2. The dual-mode cooled solid-state circuit breaker according to claim 1, characterized in that, The copper-clad ceramic plate (2) consists of three layers: top copper cladding (2-1), AlN insulating ceramic sheet (2-2), and bottom copper cladding (2-3). The power semiconductor die is sintered on the top copper cladding (2-1) to realize the circuit breaker closing / breaking function. The molybdenum copper heat expansion block (7) is engraved with heat exchange microstructures around its perimeter to expand the heat dissipation area and provide heat capacity for the power semiconductor die. Its bottom is sintered with the source electrode of the power semiconductor die, and its top is welded or sintered with the copper conductive strip (8) to form an electrical circuit. A power terminal (6) is led out from the top copper cladding (2-1) of the copper-clad ceramic plate for connection with the circuit outside the boiling phase change cooling cavity.

3. The dual-mode cooled solid-state circuit breaker according to claim 1, characterized in that, The electronic fluorinated liquid (5) is used to treat the thermal shock under transient overcurrent conditions of the solid circuit breaker; the bottom flange of the boiling phase change cooling chamber (4) and the circumferential mounting contact surface of the manifold microchannel heat sink (3) are provided with O-ring grooves and equipped with O-rings to prevent leakage of electronic fluorinated liquid (5); the side wall of the boiling phase change cooling chamber (4) is provided with a liquid replenishment port (20) and a liquid drain port (21), and the top of the chamber is equipped with a sealing plug (9) for leading out signal lines, and a pressure gauge (22) is provided for pressure monitoring.

4. The dual-mode cooled solid-state circuit breaker according to claim 1, characterized in that, The condenser (10) is used to cool the gaseous electronic fluorinated liquid after boiling phase change. The contact surface between the top flange of the boiling phase change cooling chamber (4) and the condenser (10) is provided with an O-ring groove and equipped with an O-ring to ensure the airtightness of the chamber. The condenser (10) is equipped with a condenser cooling water inlet pipe (13) and a condenser cooling water outlet pipe (14) for connecting the cooling water branch. The condenser (10) and the manifold microchannel radiator (3) share the cooling water source but the branch is independent. A solenoid valve (15) and a check valve are provided at the inlet of the condenser cooling water inlet pipe (13) to control the opening and closing of the water circuit of the condenser (10). The speed regulating pump (16) is installed at the cooling water inlet of the main channel. Under steady-state conditions, it operates at the rated preset pump speed, and under transient conditions, it operates at the overflow preset pump speed.

5. The dual-mode cooled solid-state circuit breaker according to claim 1, characterized in that, The drive and control system (17) collects the on-state voltage drop of the power semiconductor die in real time, identifies steady-state, transient and short-circuit conditions according to the set threshold, and judges the closing / opening logic control and cooling mode switching of the solid circuit breaker according to the working state; at the same time, it collects the inlet and outlet temperature and pressure difference of the cooling water of the manifold microchannel radiator (3) and the pressure of the boiling phase change cooling chamber (4) for safety limiting.

6. A thermal management method for a solid-state circuit breaker based on dual-mode cooling as described in any one of claims 1-5, characterized in that, include: During normal operation, the on-state voltage drop of the power semiconductor die of the solid-state circuit breaker is low. At this time, the drive and control system (17) determines that the solid-state circuit breaker is in steady-state operation and is in normal cooling mode, that is, the manifold microchannel heat sink (3) is working normally, the speed regulating pump (16) is running at the rated preset pump speed, the solenoid valve (15) is kept closed, and the boiling phase change cooling chamber (4) and condenser (10) are not working; the temperature of the power semiconductor die is designed to be 80~90℃ under steady-state operation; when the on-state voltage drop of the power semiconductor die exceeds the steady-state operation threshold and is lower than the short-circuit fault threshold, the drive... The control system (17) determines that the solid-state circuit breaker is in an overcurrent condition and switches the solid-state circuit breaker to the transient cooling mode. Under the overcurrent condition, the power consumption of the power semiconductor die increases sharply and the chip temperature gradually rises. When the local temperature exceeds the boiling point of the electronic fluorinated liquid (5) by a certain degree of superheat, the electronic fluorinated liquid (5) is automatically triggered to boil. In the transient cooling mode, the solenoid valve (15) is opened to start the condenser (10) to cool the boiling phase-change gaseous electronic fluorinated liquid. The gaseous working fluid is condensed and returned by the condenser (10). At the same time, the preset pump speed of the cooling water speed regulating pump (16) is increased to increase the flow rate of the manifold (3-1). Cooling water flow rate enhances the heat dissipation capacity of the manifold microchannel radiator (3) and prevents the cooling water in the microchannel (3-2) from boiling and blocking the channel, ensuring the cooling effect; when the overcurrent condition ends and the conduction voltage drop drops below the steady-state operating threshold, the solenoid valve (15) is closed, and the pump speed of the speed regulating pump (16) is reduced to the rated value, and the solid-state circuit breaker returns to the normal cooling mode; when the conduction voltage drop of the power semiconductor die (1) exceeds the short-circuit fault threshold, the solid-state circuit breaker operates in the short-circuit condition, and the drive and control system (17) determines that a short-circuit fault has occurred in the line where the solid-state circuit breaker is located and controls the solid-state circuit breaker to operate. The faulty circuit is disconnected, and the solid-state circuit breaker switches to transient cooling mode. The drive and control system (17) attempts to reclose the circuit after the fault is disconnected by the solid-state circuit breaker within a set time. If the reclosing is successful, the solid-state circuit breaker resumes normal cooling mode after the conduction voltage of the power semiconductor die drops below the steady-state operating threshold. If the reclosing fails, the drive and control system stops attempting to reclose the circuit. After the pressure of the boiling phase change cooling chamber (4) drops to normal pressure, the solenoid valve (15) is closed. After the water temperature of the manifold cooling water outlet pipe (12) drops to room temperature, the speed regulating pump (16) is closed. The solid-state circuit breaker enters standby mode and waits for the circuit to be repaired.

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