An integrated insulated cascaded power module and a control method thereof

Abstract

The application relates to an integrated insulation cascade power module and a control method thereof. The integrated insulation cascade power module comprises a low-voltage cavity and a high-voltage cavity, a plurality of high-voltage modules are arranged in the high-voltage cavity in a stacked mode, each high-voltage module is divided into a plurality of heat-emitting areas according to a device arrangement mode, an integrated insulation mechanism is arranged between the low-voltage cavity and the high-voltage cavity and is used for integrally isolating the low-voltage cavity and the high-voltage cavity, a heat dissipation air duct is arranged in the high-voltage cavity, corresponding air deflectors are arranged in the heat dissipation air duct according to corresponding heat-emitting areas, and the air deflectors are used for guiding air to the corresponding heat-emitting areas; and a heat dissipation fan is arranged on one side of the high-voltage module and is communicated with the heat dissipation air duct. The application breaks the limitation of a traditional single insulation barrel, integrally and uniformly isolates high and low voltages, saves insulation cost, reduces assembly difficulty, saves occupied space, and further solves the technical problem of low heat dissipation efficiency caused by an excessively thick insulation wall in the prior art.

Description

Technical Field

[0001] This application relates to the field of electronic equipment technology, and in particular to an integrated insulated cascaded power module and its control method. Background Technology

[0002] Solid-state transformers (SSTs) will be widely used in data center power supply and supercharging station power supply systems in the future. Current SST architectures typically employ a cascaded architecture, as shown in the reference... Figure 1 As shown. Each phase of an SST is typically divided into N units. Since the SST draws power directly from the medium-voltage grid, such as 10kV, the input and output sides of the SST require medium-voltage insulation design. Currently, the common practice is to make a separate insulation tank for each unit, such as... Figure 2 The dashed box shown has the following problems: high insulation cost, difficult assembly, large space occupied by insulation components, and difficulty in increasing power density. Moreover, each insulation barrel needs to support the circuit and has sufficient structural strength. In actual design, the choice of insulation material is also limited. Epoxy resin casting is usually used, which is complicated and costly.

[0003] Furthermore, existing single-unit insulating shell designs require each individual insulating shell to have a very thick wall to meet insulation and creepage distance requirements under high-voltage environments. (Refer to...) Figure 3 As shown. This thick, single-unit insulating wall significantly increases the physical distance between the high-pressure and low-pressure chambers, severely hindering the dissipation of internal heat. To ensure basic heat dissipation, existing equipment must rely on larger, more powerful cooling fans for forced air cooling. This not only results in a large overall size and increased noise, but also, because each insulating barrel independently blocks the airflow, the overall heat dissipation efficiency of the system remains very low.

[0004] Based on the above, how to solve the technical problems of high cost, high difficulty, large space, and large fan size and low heat dissipation efficiency caused by the large wall thickness of the existing single-unit insulating shell solution is a problem to be solved in this technical field. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, this application provides an integrated insulated cascaded power module and its control method. By combining high and low voltage partitioning and an integrated insulated shell with an internal air duct design, the heat dissipation is effectively solved by the large wall thickness of the existing single insulated shell, which hinders the heat dissipation and improves the overall heat dissipation efficiency. Moreover, by replacing the original single insulated shell with an integrated insulated shell, insulation costs are saved, assembly difficulty is reduced, and space is saved.

[0006] The embodiments of this application adopt the following technical solutions: In a first aspect, this application provides an integrated insulated cascaded power module, comprising: The system includes a low-pressure chamber and a high-pressure chamber. Multiple high-pressure modules are stacked in the high-pressure chamber, and each high-pressure module is divided into multiple heating areas according to the device arrangement. An integrated insulation mechanism is disposed between the low-pressure chamber and the high-pressure chamber to isolate the low-pressure chamber and the high-pressure chamber as a whole; A heat dissipation duct is provided inside the high-pressure chamber. A corresponding air guide plate is provided inside the heat dissipation duct according to the corresponding heat-generating area. The air guide plate is used to direct the air to the corresponding heat-generating area. A cooling fan is located on one side of the high-voltage module and is connected to the cooling air duct.

[0007] The above technical solution breaks through the limitations of traditional single-unit insulation barrels, and isolates high and low voltage as a whole, saving insulation costs, reducing assembly difficulty, and saving space. In addition, after isolation, only a cooling fan needs to be set for the high-voltage module to cool it down, while the low-voltage side can rely on the overall cooling effect of the system without the need for a separate cooling fan. Compared with the traditional method of mixing high and low voltage, which requires overall cooling and thus large fan size requirements, this application can use a smaller cooling fan. At the same time, with the combination of air guide plates, the cold air can flow precisely through the heat-generating areas of each high-voltage module, solving the technical problem of low heat dissipation efficiency caused by excessively thick insulation walls in the prior art.

[0008] In some embodiments, the integrated insulation mechanism includes an insulating shell that partially surrounds the high-voltage chamber and a transformer tank located between the low-voltage chamber and the high-voltage chamber; the side of the transformer tank facing the high-voltage chamber forms an isolation space with the insulating shell, surrounding the high-voltage chamber inside and isolating the low-voltage chamber outside.

[0009] The above technical solution constructs a complete high-voltage insulation isolation space by combining the insulating shell and the transformer tank. This not only meets the electrical clearance requirements for high-voltage module stacking, but also utilizes the tank wall as an insulating medium, thus improving space utilization.

[0010] In some embodiments, the transformer tank has a high-voltage side transformer winding interface on the side facing the high-voltage chamber and a low-voltage side transformer winding interface on the side facing the low-voltage chamber. Both the high-voltage side transformer winding interface and the low-voltage side transformer winding interface are provided with sealing plates. The transformer tank has skirts around its perimeter on the side facing the high-voltage chamber to extend the creepage distance.

[0011] Through the above technical solution, while achieving safe interconnection between the high and low voltage windings across the inside and outside of the oil tank, the umbrella skirt design effectively extends the surface creepage distance on the high voltage side, preventing high voltage discharge along the surface of the transformer oil tank.

[0012] In some embodiments, the air guide plate includes two types: the first type of air guide plate is symmetrically arranged at the end of the heat-generating area near the cooling fan, and is used to concentrate and guide the air to the heat-generating area; the second type of air guide plate is a single piece arranged in the middle of the heat-generating area, and is used to guide the air to the side of the heat-generating area where the device is located.

[0013] Through the above technical solution, the two types of air guide plates work together. The first type is responsible for concentrating the air, and the second type is responsible for accurately guiding the airflow to the heat-generating surface of the device, which avoids short-circuiting or dissipating the airflow in the stacked space and maximizes the local heat dissipation efficiency.

[0014] Secondly, this application provides a control method for an integrated insulated cascaded power module, applied to the integrated insulated cascaded power module described in the first aspect, comprising: Obtain real-time temperature data of the multiple heating areas contained in each high-pressure module inside the high-pressure chamber; The overall module temperature of each high-voltage module is calculated based on the real-time temperature data of multiple heating areas belonging to the same high-voltage module. Calculate the overall temperature difference between the high-voltage modules stacked in the high-voltage chamber and at different physical heights; When the overall temperature difference of the module exceeds the preset temperature difference threshold, the spatial thermal equilibrium modulation strategy is triggered. By adjusting the speed of the cooling fan and / or dynamically adjusting the output power of the corresponding high-voltage module, the heat generation of the high-voltage module with a high overall module temperature is reduced.

[0015] By combining the control algorithm with the stacked physical structure, the physical drawbacks of overheating of the upper module and cooling of the lower module caused by rising hot air are overcome. This achieves hardware and software thermal coordination control based on physical spatial location and solves the problem of heat accumulation in the integrated space.

[0016] In some embodiments, the dynamic adjustment of the output power of the corresponding high-voltage module specifically includes: Reduce the PWM duty cycle, carrier switching frequency, or output fundamental voltage amplitude of the high-voltage module with a high overall module temperature; simultaneously... Increase the PWM duty cycle, carrier switching frequency, or output fundamental voltage amplitude of the high-voltage module with a lower overall module temperature to maintain the total output voltage or total output power of the cascaded high-voltage modules.

[0017] Through the above technical solution, while ensuring the overall system output energy stability, dynamic transfer of heat load is achieved between the stacked high-voltage modules, effectively preventing local modules from triggering protection shutdown due to overheating.

[0018] In some implementations, when the spatial thermal equalization modulation strategy is triggered, the control method further includes: Extract the current global maximum temperature and the rate of change of the maximum temperature from the real-time temperature data of all heat-generating areas; Combining the wind resistance model when airflow passes through the first type of air guide plate and the second type of air guide plate, and based on the global maximum temperature and the rate of change of the maximum temperature, the input voltage signal of the cooling fan corresponding to the current global maximum temperature is dynamically adjusted in advance to increase the airflow through the corresponding heat-generating area in advance.

[0019] By incorporating the physical wind resistance characteristics of the air guide plate into the fan control algorithm through the above technical solution, adaptive dynamic air cooling adjustment is achieved, which reduces noise and saves energy under low load and enhances the airflow and heat dissipation capacity in advance when high heat load changes suddenly.

[0020] In some embodiments, the control method further includes an asymmetric insulation capacitor leakage current suppression strategy: When performing PWM modulation on multiple high-voltage modules, the number of switching transistors operating simultaneously is limited by constraining the state combination of the power switching transistors of the multiple high-voltage modules, thereby suppressing the high-frequency common-mode voltage variation rate applied to the transformer tank interface and reducing the high-frequency leakage current caused by the parasitic capacitance of the asymmetrically arranged integrated insulation mechanism.

[0021] Through the above technical solution, a targeted leakage current suppression strategy was specifically designed to address the spatial parasitic capacitance imbalance problem caused by the unique asymmetric integrated insulation structure of the oil tank and shell in this application. This reduces leakage current on the insulation surface and improves the electromagnetic compatibility and insulation life of the system.

[0022] In some implementations, the control method further includes a dynamic voltage equalization control strategy based on a stacked structure: Real-time monitoring of sudden voltage changes in the external power grid; When transient voltage fluctuations occur, the transient voltage difference between two adjacent high-voltage modules in the physical stacking space is limited to not exceed the internal creepage tolerance threshold of the integrated insulation mechanism; if it is determined that the transient voltage difference exceeds the creepage tolerance threshold, the DC bus voltage reference value of the corresponding adjacent high-voltage module is actively adjusted.

[0023] The above technical solution strongly binds the electrical voltage equalization control with the physical creepage distance of the integrated insulation mechanism, preventing surface creepage breakdown of adjacent high-voltage modules along the inner wall of the integrated insulation mechanism due to excessive potential difference under transient conditions.

[0024] In some embodiments, the control method further includes a spatial stress redistribution strategy under fault-tolerant conditions: When a fault is detected in any of the high-voltage modules and it is electrically bypassed, the specific physical location of the bypassed high-voltage module in the high-voltage cavity stack structure is recorded. Based on the specific physical location, the spatial electric field distribution inside the integrated insulation mechanism is reassessed, and the steady-state voltage distribution reference value of the remaining normally operating high-voltage modules is recalculated and updated.

[0025] The above technical solutions ensure that when a module fails and bypasses, the remaining modules will not share the increased voltage, preventing the insulation shell or transformer tank near the fault point from experiencing an excessively high concentrated electric field, thus improving the long-term safe operation capability of the equipment under redundant fault-tolerant conditions.

[0026] In summary, this application includes at least the following beneficial technical effects: 1. This invention breaks the limitations of traditional single-unit insulation barrels, achieving unified isolation of high and low voltage, saving insulation costs, reducing assembly difficulty, and saving space. In addition, after isolation, only a cooling fan needs to be installed for the high-voltage module to cool it down, while the low-voltage side can rely on the overall cooling effect of the system without the need for a separate cooling fan. Compared with the traditional method of mixing high and low voltage, which requires overall cooling and thus large fan size requirements, this application can use a smaller cooling fan. At the same time, with the combination of air guide plates, the cool air can flow precisely through the heat-generating areas of each high-voltage module, solving the technical problem of low heat dissipation efficiency caused by excessively thick insulation walls in the prior art. 2. By combining the control algorithm with the stacked physical structure, the physical drawbacks of overheating of the upper module and cooling of the lower module caused by rising hot air are overcome. This achieves hardware and software thermal coordination control based on physical spatial location, solving the problem of heat accumulation in the integrated space. Furthermore, while ensuring the overall stable output energy of the system, dynamic transfer of heat load is achieved between the stacked high-voltage modules, effectively preventing local modules from triggering protection shutdown due to overheating. 3. It ensures that when a module fails and bypasses, the remaining modules will not share the increased voltage, preventing the insulation shell or transformer tank near the fault point from experiencing an excessively high concentrated electric field, thus improving the long-term safe operation capability of the equipment under redundant fault-tolerant conditions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a cascaded architecture of a conventional solid-state transformer provided in an embodiment of this application; Figure 2 This is a schematic diagram of the overall structure of a conventional SST provided in the embodiments of this application; Figure 3 This is a schematic diagram of fan operation under a conventional single-module design provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of an integrated insulated cascaded power module provided in an embodiment of this application; Figure 5 A schematic diagram of the heat dissipation air duct and air guide plate design for a single high-voltage module provided in an embodiment of this application; Figure 6 A schematic diagram of a cooling fan provided in an embodiment of this application specifically designed to deliver air to a high-voltage module; Figure 7 This is a schematic diagram of the structural design of a single transformer tank provided in an embodiment of this application; Figure 8 A schematic diagram of the transformer tank facing the high-voltage side provided in an embodiment of this application; Figure 9 This is a schematic diagram of a first simplified scheme provided in the embodiments of this application; Figure 10 This is a schematic diagram of a second simplified scheme provided in the embodiments of this application; Figure 11 A flowchart illustrating the control method for an integrated insulated cascaded power module provided in an embodiment of this application.

[0029] In the diagram: 1. Low-pressure chamber; 2. High-pressure chamber; 3. High-pressure module; 4. Integrated insulation mechanism; 41. Insulating shell; 42. Transformer oil tank; 421. High-voltage side transformer winding interface; 422. Sealing plate; 423. Umbrella skirt; 5. Heat dissipation duct; 6. Air guide plate; 7. Cooling fan; 100. High-voltage chamber; 200. Low-voltage area; 300. Insulating outer shell; 400. Fan; 500, Insulating shell; 600, Transformer primary side; 700, Transformer secondary side; 800, Part One; 900, Part Two. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0031] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Example 1 It should be noted that existing cascaded power modules typically have a separate, heavy insulating casing for each high-voltage module, significantly increasing the physical distance between high and low voltage levels, making it extremely difficult for internal heat to dissipate. Forcing heat dissipation would require extremely large and noisy high-power fans, resulting in overall low cooling efficiency. (Reference) Figure 3 As shown, the existing single module includes a high-voltage cavity 100 and a low-voltage region 200. The high-voltage cavity 100 is surrounded by an insulating shell 300 to separate it from the low-voltage region 200. In this case, the fan 400 needs to simultaneously dissipate heat from both the high-voltage cavity 100 and the low-voltage region 200, resulting in a larger size requirement.

[0033] Based on the above issues, refer to Figure 4 and Figure 5 As shown, this embodiment 1 provides an integrated insulated cascaded power module, including a low-voltage chamber 1 and a high-voltage chamber 2. High-voltage modules 3 are uniformly arranged within the high-voltage chamber 2, and low-voltage modules are uniformly arranged within the low-voltage chamber 1, separated by an integrated insulation mechanism 4. This embodiment breaks with the traditional design of single-unit insulation, employing an integrated insulation mechanism 4 positioned between the low-voltage chamber 1 and the high-voltage chamber 2. This mechanism uniformly encloses the multiple high-voltage modules 3 stacked within the high-voltage chamber 2 and isolates them from the low-voltage chamber 1. Furthermore, this embodiment deploys a heat dissipation duct 5 within the high-voltage chamber 2 and, based on the heat-generating areas of each high-voltage module 3, specifically sets corresponding air guide plates 6, working in conjunction with a cooling fan 7 on one side for heat dissipation.

[0034] With this architecture, the thick walls of the individual insulating casing are removed, allowing the cooling fan 7 to be smaller, such as 1 / 2 or 2 / 3 of its original size. (See reference...) Figure 6 As shown, the cooling fan 7 is specifically designed to deliver airflow to the high-pressure module 3. Its size is smaller than that of traditional models, allowing the low-pressure chamber 1 to rely solely on natural cooling or system airflow cooling. (Reference) Figure 5 The intervention of the air guide plate 6 prevents the cold air from spreading blindly, but instead allows it to precisely penetrate the heat-generating areas of each high-voltage module 3. The combination of the two greatly saves equipment size and fan energy consumption, and solves the problem of low heat dissipation efficiency caused by excessively thick insulation walls.

[0035] It should be noted that if a large insulating shell is simply used to cover the high-voltage cavity, the manufacturing cost of the insulating shell is relatively high; at the same time, high-voltage creepage or surface breakdown can easily occur at the electrical connection between the high-voltage winding and the low-voltage side through the wall.

[0036] Based on the above problems, this embodiment employs an ingenious asymmetrical design for the integrated insulation mechanism 4: it is composed of a semi-enclosed insulating shell 41 and a transformer tank 42 joined together. One side of the transformer tank 42 directly serves as the insulating wall for the high-voltage chamber 2. To solve the insulation problem of wiring through walls, reference is made to... Figure 7 As shown, the transformer tank 42 has a high-voltage side transformer winding interface 421 on the side facing the high-voltage chamber 2, and is sealed with a sealing plate 422 to prevent oil leakage. Additionally, a wavy or serrated skirt 423 is designed around the perimeter of this side to increase the creepage distance. Correspondingly, the transformer tank 42 also has a low-voltage side transformer winding interface on the side facing the low-voltage chamber 1, and is sealed with a sealing plate 422 to prevent oil leakage. It should be noted that... Figure 7 The diagram shows the oil tank used for a single transformer. To match the multi-module stacking design adopted in this embodiment, simply increase the length of the oil tank, and the internal transformers can also be stacked and arranged corresponding to the high-voltage and low-voltage sides. (Refer to...) Figure 8 As shown, when multiple transformers are stacked inside the transformer tank 42, each transformer has a corresponding winding interface on the side of the tank. The sealing plate 422 can be designed separately to seal these winding interfaces to prevent oil leakage, or it can be designed as an integrated whole to seal these winding interfaces uniformly to prevent oil leakage.

[0037] By reusing the transformer tank wall as the insulating medium, the amount of material used in the insulating shell is significantly reduced, improving the space utilization of the high-voltage chamber 2. The design of the surrounding umbrella skirts 423, based on the principle of high-voltage surface discharge, multiplies the physical creepage distance between high and low voltage interfaces and between adjacent high-voltage modules, preventing high-voltage arcing breakdown.

[0038] It should be noted that inside the stacked high-pressure chamber, even with a fan blowing air, the airflow can easily escape from the gaps, causing a short circuit in the airflow. This results in the IGBT devices or heat sinks located deep inside or at the core of the heat generation not receiving enough cool air.

[0039] To address the aforementioned issues, this embodiment incorporates two types of air guide plates 6 within the heat dissipation duct 5. (See reference...) Figure 5 The first type of air guide plate 6 is symmetrically arranged in the shape of a horn or funnel at the end of the heat-generating area near the cooling fan 7, which serves to concentrate the airflow; the second type of air guide plate 6 is a single piece arranged at an angle in the middle of the heat-generating area, which serves to guide and block the airflow, forcibly guiding the horizontal airflow in the required direction so that it directly hits the heat-generating device (such as the heat sink substrate).

[0040] By combining two types of air guides, the high-speed airflow is first concentrated and then precisely redirected to hit the heating surface of the device, completely eliminating the ineffective dissipation of cooling air in the stacking space and maximizing the local heat exchange efficiency.

[0041] As a simplified alternative, refer to Figure 9 As shown, the integrated insulation mechanism 4 can be designed as an insulating shell 500 that completely surrounds the high-voltage chamber 2 and all high-voltage modules 3. The primary side 600 of the transformer is located inside the shell and communicates with the high-voltage chamber 2, while the secondary side 700 of the transformer is located outside the shell and communicates with the low-voltage chamber 1. (Reference) Figure 10 As shown, the integrated insulation mechanism 4 can also be designed as a split insulation shell structure, divided into two parts. The first part 800 semi-encloses the high-voltage chamber 2, and the second part 900 exposes the transformer to the air. The high-voltage side is connected to the high-voltage chamber 2, and the low-voltage side is connected to the low-voltage chamber 1. The two parts can be fixed by screws or other connecting parts.

[0042] In the above scheme, the insulating shell only serves an insulating function and does not need to serve a fixing function. The choice of material is not limited by strength and can be an insulating material such as epoxy resin or FR4.

[0043] Example 2 Based on the integrated insulated cascaded power module provided in Embodiment 1, Embodiment 2 provides its control method to specifically address some problems after structural changes.

[0044] It should be noted that the high-voltage modules 3 are physically stacked vertically, and each module contains multiple heat-generating areas formed by the arrangement of components. The rising hot air causes the overall temperature of the high-voltage modules stacked on top to be significantly higher than that of the modules below. Furthermore, the minimum power regulation unit for electrical control is the high-voltage module 3 itself; it is not possible to individually dredge a specific localized heat-generating area within the module.

[0045] Based on the above, the control method in this embodiment adopts the following means: Establish an aggregation mapping algorithm between heating areas and high-voltage modules. Assume that high-voltage cavity 2 contains eight high-voltage modules 3, labeled M1 to M8 from bottom to top. Taking one high-voltage module as an example, it is arranged in two layers, with two heating areas per layer, for a total of four heating areas. (Reference) Figure 11 The control methods include: Step S1: Real-time acquisition of the temperatures Ti1, Ti2, Ti3, Ti4 of the four heating regions inside the i-th high-voltage module Mi.

[0046] Step S2: Calculate the overall module temperature Tmod_i of the high-voltage module. The algorithm can use the average value method: Tmod_i=(Ti1+Ti2+Ti3+Ti4) / 4; or for bias protection, the maximum value method can be used: Tmod_i=max(Ti1,Ti2,Ti3,Ti4).

[0047] Step S3: Calculate the overall temperature difference ΔT between the high-voltage module M8 located at the top layer and the high-voltage module M1 located at the bottom layer.

[0048] Step S4: When ΔT > 20℃ (preset temperature difference threshold), the system activates the thermal equilibrium transfer algorithm: the system maintains the total output power Ptotal of the entire unit unchanged, and adjusts the power distribution coefficient αi of the high-voltage module as the basic unit. For example: reduce the carrier switching frequency of the overheated M8 module at the top layer (e.g., from 5kHz to 3kHz) or reduce its output fundamental voltage amplitude reference value; at the same time, proportionally increase the carrier switching frequency or output voltage amplitude of the cooler M1 module at the bottom layer.

[0049] The above solution breaks down the barrier between local temperature measurement and overall module power control. Without affecting the overall power grid's energy transmission, it transfers the heat load from modules at higher physical locations to modules at lower physical locations, thus solving the problem of vertical heat accumulation in the integrated high-voltage chamber.

[0050] It should be noted that traditional air-cooling control often uses average temperature feedback, resulting in a significant lag in response. Furthermore, in stacked modules, the most dangerous area is often a specific heat-generating region (e.g., a sudden temperature spike in the junction of an IGBT at the end of the air duct), rather than the overall module temperature. If the fan cannot accelerate in advance when a transient overheating occurs in a particular area, the device is highly susceptible to burnout.

[0051] Based on the above, this embodiment no longer uses the overall temperature of the high-voltage module, but directly scans the real-time temperature data of all heat-generating areas inside the high-voltage chamber 2, extracts the current global maximum temperature Tmax (i.e., finds the most dangerous hot spot area), and calculates the maximum temperature change rate dTmax / dt of the hot spot.

[0052] Furthermore, the system controller pre-embeds the physical wind resistance model parameters Rwind when the airflow passes through the first type of air guide plate 6 and the second type of air guide plate 6. The feedforward control algorithm formula is designed as: Ufan=Kp×Tmax+Kd×dTmax / dt+f(Rwind). Where Ufan is the control signal output to the cooling fan 7 (such as PWM duty cycle); Kp is the proportional control coefficient, and Kd is the differential feedforward coefficient. When a sudden change in the power grid load causes a local heat-generating area to have a maximum dTmax / dt, even if the overall module temperature has not yet risen, the algorithm will instantly increase the fan speed and overcome the wind resistance delay caused by the air guide plate 6, accurately delivering strong airflow to that heat-generating area.

[0053] The above solution achieves dynamic air-cooling adjustment based on the most vulnerable local area. It gives the system the ability to predict heat dissipation transiently, reducing speed and noise at low loads and increasing airflow in advance when there are sudden changes in local thermal load, thus preventing core components from being damaged by thermal shock.

[0054] It should be noted that, due to the aforementioned integrated insulated cascaded power module employing an asymmetrical assembly structure of the insulating housing 41 and the transformer tank 42, the parasitic capacitance Cp of each high-voltage module 3 to ground is no longer balanced. When multiple modules simultaneously perform PWM high-frequency switching operations, a high common-mode voltage change rate (dv / dt) may be generated, which in turn leads to severe high-frequency leakage current (i=Cp×dv / dt) through the parasitic capacitance, damaging the insulation life.

[0055] To address the aforementioned issues, this embodiment incorporates switching transistor state combination constraints into the control logic during multi-carrier phase-shifted PWM (CPS-PWM) modulation. Assuming there are eight cascaded high-voltage modules 3 within the high-voltage chamber 2, the control algorithm forcibly limits the total number of switching transistors undergoing state transitions (from 0 to 1 or from 1 to 0) within any microsecond period to no more than Nmax (e.g., setting Nmax=2). If the algorithm calculates that three modules need to transition simultaneously at the next moment, the transition pulse of one of the modules is artificially delayed by a small dead time (e.g., 2μs).

[0056] The above solution breaks down the high-frequency common-mode voltage step into small steps from the source, significantly reducing the high-frequency common-mode dv / dt instantaneously superimposed on the transformer tank 42 interface, effectively reducing the parasitic high-frequency leakage current caused by the asymmetric structure, and improving insulation life and electromagnetic compatibility.

[0057] It should be noted that when a transient overvoltage occurs in the power grid (such as a lightning strike or short-circuit drop), due to the difference in dynamic response of the cascaded system, a huge voltage difference may instantaneously occur between two adjacent high-voltage modules (such as module A and module B) in the stacking space. If this difference is greater than the physical creepage tolerance of the surface of the integrated insulation mechanism 4, arcing will occur.

[0058] Based on the above issues, this embodiment sets an absolute internal creepage tolerance threshold Vcreep_limit (e.g., 1500V) according to the actual physical dimensions of the integrated insulation mechanism 4 and the umbrella skirt 423. During operation, the controller not only controls voltage equalization but also adds a forced limiting mechanism: it calculates the bus voltage Vdc_A and bus voltage Vdc_B of physically adjacent modules A and B in real time. When |Vdc_A-Vdc_B| ≥ Vcreep_limit × 0.9 (warning coefficient), regardless of the output result of the control loop, the system forcibly lowers the DC bus reference value of the high-voltage module and raises the bus reference value of the low-voltage module, clamping the transient difference between the two within a safe distance.

[0059] The above scheme endows the control algorithm with spatial physical safety awareness, completely preventing internal insulation creepage breakdown caused by excessive potential difference under transient abnormal conditions, and improving hardware survivability.

[0060] It should be noted that the cascaded system has a redundant bypass function. When the high-voltage module located in the middle of the stack (e.g., module 3) fails and is mechanically bypassed (short-circuited to 0V), its adjacent modules 2 and 4 immediately have to share the higher grid voltage. At this time, the 0V module 3 acts like a low-potential trap, causing a sharp increase in the spatial electric field stress from modules 2 and 4 towards module 3, which can easily break down the air or insulation wall in between.

[0061] To address the aforementioned issues, this embodiment pre-defines a spatial position matrix in the system software that maps to the physical stacking positions. When a module with a position index of K is detected to be bypassed (electrical position zero), the system re-evaluates the electric field. When redistributing the steady-state operating voltage Vref of the remaining healthy modules, the average distribution strategy is no longer used. The algorithm forcibly sets: the steady-state voltage reference values ​​of the two modules immediately above and below the fault point K (K-1 and K+1) are reduced, for example, by 10%; the steady-state voltage reference values ​​of modules farther from the fault point (such as K-2 and K+2) are increased, for example, by 10% (to compensate for the total voltage).

[0062] By employing the above solution, the concentrated spatial electric field intensity around the fault point is cleverly reduced while sacrificing minor voltage equalization performance. This ensures that in fault-tolerant modes where modules are damaged, the insulation structure will not suffer secondary damage due to excessively high local electric fields, significantly extending the safe operating time under fault conditions.

[0063] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An integrated insulated cascaded power module, characterized in that, include: The high-pressure chamber (1) and the high-pressure chamber (2) are provided. Multiple high-pressure modules (3) are stacked in the high-pressure chamber (2). Each high-pressure module (3) is divided into multiple heating areas according to the device arrangement. An integrated insulation mechanism (4) is disposed between the low-pressure chamber (1) and the high-pressure chamber (2) to isolate the low-pressure chamber (1) and the high-pressure chamber (2) as a whole; A heat dissipation duct (5) is provided inside the high-pressure chamber (2). A corresponding air guide plate (6) is provided inside the heat dissipation duct (5) according to the corresponding heat-generating area. The air guide plate (6) is used to guide the air to the corresponding heat-generating area. A cooling fan (7) is located on one side of the high-voltage module (3) and is connected to the cooling duct (5).

2. The integrated insulated cascaded power module according to claim 1, characterized in that, The integrated insulation mechanism (4) includes an insulating shell (41) that partially surrounds the high-voltage chamber (2) and a transformer tank (42) located between the low-voltage chamber (1) and the high-voltage chamber (2); the side of the transformer tank (42) facing the high-voltage chamber (2) forms an isolation space with the insulating shell (41), surrounding the high-voltage chamber (2) inside and isolating the low-voltage chamber (1) outside.

3. The integrated insulated cascaded power module according to claim 2, characterized in that, The transformer tank (42) has a high-voltage side transformer winding interface (421) on the side facing the high-voltage chamber (2) and a low-voltage side transformer winding interface on the side facing the low-voltage chamber (1). Both the high-voltage side transformer winding interface (421) and the low-voltage side transformer winding interface are provided with sealing plates (422). The transformer tank (42) has umbrella skirts (423) around the side facing the high-voltage chamber (2) to extend the creepage distance.

4. The integrated insulated cascaded power module according to claim 1, characterized in that, The air guide plate (6) includes two types. The first type of air guide plate (6) is symmetrically arranged at the end of the heat-generating area near the heat dissipation fan (7) to concentrate the airflow to the heat-generating area. The second type of air guide plate (6) is a single piece arranged in the middle of the heat-generating area to guide the airflow to the side of the heat-generating area where the device is located.

5. A control method for an integrated insulated cascaded power module, applied to the integrated insulated cascaded power module according to any one of claims 1-4, characterized in that, include: Obtain real-time temperature data of the multiple heating areas contained in each high-pressure module (3) inside the high-pressure chamber (2); Based on the real-time temperature data of multiple heating areas belonging to the same high-voltage module (3), the overall module temperature of each high-voltage module (3) is calculated. Calculate the overall temperature difference between the high-pressure modules (3) stacked in the high-pressure chamber (2) and at different physical heights; When the overall temperature difference of the module exceeds the preset temperature difference threshold, the spatial thermal equilibrium modulation strategy is triggered. By adjusting the speed of the cooling fan (7) and / or dynamically adjusting the output power of the corresponding high voltage module (3), the heat generation of the high voltage module (3) with a high overall module temperature is reduced.

6. The control method for the integrated insulated cascaded power module according to claim 5, characterized in that, The dynamic adjustment of the output power of the corresponding high-voltage module (3) specifically includes: Reduce the PWM duty cycle, carrier switching frequency, or output fundamental voltage amplitude of the high-voltage module (3) with a high overall module temperature; simultaneously... Increase the PWM duty cycle, carrier switching frequency, or output fundamental voltage amplitude of the high-voltage module (3) with a lower overall module temperature to maintain the total output voltage or total output power of the cascaded high-voltage modules (3) unchanged.

7. The control method for the integrated insulated cascaded power module according to claim 5, characterized in that, When the spatial thermal equalization modulation strategy is triggered, the control method further includes: Extract the current global maximum temperature and the rate of change of the maximum temperature from the real-time temperature data of all heat-generating areas; Combining the wind resistance model when the airflow passes through the first type of air guide plate (6) and the second type of air guide plate (6), the input voltage signal of the cooling fan (7) corresponding to the current global maximum temperature is dynamically adjusted according to the global maximum temperature and the maximum temperature change rate, so as to increase the airflow through the corresponding heat-generating area in advance.

8. The control method for the integrated insulated cascaded power module according to claim 5, characterized in that, The control method also includes an asymmetric insulation capacitor leakage current suppression strategy: When PWM modulation is applied to multiple high-voltage modules (3), the number of switching transistors that operate simultaneously is limited by constraining the state combination of the power switching transistors of multiple high-voltage modules (3), so as to suppress the high-frequency common-mode voltage variation rate applied to the interface of the transformer tank (42), thereby reducing the high-frequency leakage current caused by the parasitic capacitance of the asymmetrically arranged integrated insulation mechanism (4).

9. The control method for the integrated insulated cascaded power module according to claim 5, characterized in that, The control method also includes a dynamic voltage equalization control strategy based on a stacked structure: Real-time monitoring of sudden voltage changes in the external power grid; When transient voltage fluctuations occur, the transient voltage difference between two adjacent high-voltage modules (3) in the physical stacking space is limited so that it does not exceed the internal creepage tolerance threshold of the integrated insulation mechanism (4); if it is determined that the transient voltage difference exceeds the creepage tolerance threshold, the DC bus voltage reference value of the corresponding adjacent high-voltage module (3) is actively adjusted.

10. The control method for the integrated insulated cascaded power module according to claim 5, characterized in that, The control method also includes a spatial stress redistribution strategy under fault-tolerant conditions: When any of the high-voltage modules (3) is detected to have failed and been electrically bypassed, the specific physical location of the bypassed high-voltage module (3) in the stacked structure of the high-voltage chamber (2) is recorded. Based on the specific physical location, the spatial electric field distribution inside the integrated insulation mechanism (4) is reassessed, and the steady-state voltage distribution reference value of the remaining normally operating high-voltage module (3) is recalculated and updated.

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