Efficient heat dissipation power capacitor

Abstract

The invention discloses an efficient heat dissipation power capacitor, and belongs to the technical field of power capacitors. The capacitor comprises a capacitor shell, a capacitor core and an impregnant filled between the capacitor core and the shell. The capacitor core is of a multi-layer composite dielectric film structure, and a composite dielectric film comprises matrix resin and high-heat-conduction nanometer filler which is arranged in a directional mode, so that a three-dimensional heat conduction network is formed. The impregnant is a nano composite impregnant and comprises base oil and heat-conducting nanoparticles dispersed in the base oil; a high-thermal-conductivity electrode interface layer is arranged at the contact interface of the electrode of the capacitor core and the dielectric film; and the inner wall of the capacitor shell is coated with a heat-conducting insulating coating. By constructing a full-link heat dissipation system inside the capacitor core, between the core and the shell, and outside the shell, rapid heat conduction and dissipation are achieved, the operation temperature rise is reduced, the service life is prolonged, meanwhile, the excellent electrical insulation performance is kept, and the capacitor is suitable for a high-voltage and high-power-density power electronic system.

Description

Technical Field

[0001] This application relates to the field of power capacitor technology, and in particular to a high-efficiency heat dissipation power capacitor. Background Technology

[0002] Power capacitors are core components in power systems and power electronic equipment, primarily used for reactive power compensation, filtering, and energy storage. Their operational stability directly impacts the overall efficiency and reliability of the power system. During actual operation, power capacitors generate significant heat due to dielectric and ohmic losses. If this heat cannot be dissipated promptly, the internal temperature of the capacitor will rise, leading to problems such as dielectric degradation, electrode oxidation, and impregnating agent aging. In severe cases, this can cause capacitor breakdown, bulging, or even explosion, drastically shortening the capacitor's lifespan and increasing power system maintenance costs and safety hazards.

[0003] In the existing technology, the heat dissipation methods of power capacitors mainly focus on optimizing the shell structure (such as adding heat dissipation fins), selecting shell materials with better thermal conductivity (such as aluminum alloys), or filling with ordinary impregnating agents. These methods can only achieve passive heat dissipation on the outside of the capacitor and cannot solve the problem of heat accumulation inside the capacitor core, resulting in limited heat dissipation efficiency.

[0004] Specifically, existing power capacitors have the following technical defects: First, the dielectric film of the capacitor core is mostly made of a single resin material with extremely low thermal conductivity (the in-plane thermal conductivity of conventional biaxially oriented polypropylene film is only 0.6 W / (m·K)), which cannot quickly conduct the heat generated inside the core, causing heat to accumulate inside the core; Second, the impregnating agent is mostly ordinary mineral oil or synthetic oil, which has poor thermal conductivity and cannot effectively transfer heat between the capacitor core and the outer shell; Third, there is a high contact thermal resistance at the interface between the electrodes and the dielectric film of the capacitor core, making it difficult for heat to be transferred from the electrodes to the dielectric film and then dissipated; Fourth, the inner wall of the capacitor shell does not have a dedicated thermally conductive insulation structure, resulting in low efficiency in transferring heat from the inside of the shell to the outside; Fifth, although some capacitors have an encapsulation layer, the thermal conductivity of the encapsulation material is poor, which cannot further improve the heat dissipation effect.

[0005] As power systems develop towards higher voltage, higher power, and smaller size, the power density of power capacitors continues to increase, making heat generation a more prominent issue. Existing heat dissipation technologies can no longer meet the actual usage requirements. Summary of the Invention

[0006] This invention addresses the problems of low heat dissipation efficiency, internal heat accumulation, and short service life of existing power capacitors. It provides a high-efficiency heat dissipation power capacitor by constructing a full-link heat dissipation system that includes the inside of the capacitor core, the space between the core and the shell, the shell, and the external encapsulation. This system enables rapid heat conduction and dissipation while ensuring the dielectric performance, insulation performance, and structural stability of the capacitor, thus extending its service life and meeting the application requirements of high-voltage and high-power-density scenarios.

[0007] The objective of this invention is primarily achieved through the following approach: A high-efficiency heat dissipation power capacitor includes a capacitor casing, a capacitor core disposed inside the casing, and an impregnating agent filled between the capacitor core and the casing; The capacitor core adopts a multilayer composite dielectric film structure, which includes a matrix resin and oriented high thermal conductivity nanofillers to form a three-dimensional thermally conductive network. The impregnating agent is a nanocomposite impregnating agent, comprising base oil and thermally conductive nanoparticles dispersed in the base oil; A high thermal conductivity electrode interface layer is provided at the contact interface between the electrode and the dielectric film of the capacitor core. This layer is formed by the composite curing of conductive nanomaterials and organic binders. The inner wall of the capacitor casing is coated with a thermally conductive and insulating coating.

[0008] Furthermore, the matrix resin is biaxially oriented polypropylene or polyvinylidene fluoride, with a mass fraction of 75-90%; the high thermal conductivity nanofiller is boron nitride nanosheets or alumina nanofibers, with a mass fraction of 10-25%. Biaxially oriented polypropylene (BOPP) and polyvinylidene fluoride (PVDF) are both commonly used matrix materials for dielectric films of power capacitors, possessing excellent dielectric, insulating, and mechanical properties, ensuring the basic performance of the composite dielectric film. Boron nitride nanosheets and alumina nanofibers are both highly thermally conductive and highly insulating nanomaterials; their oriented arrangement can form a continuous three-dimensional thermally conductive network, significantly improving the thermal conductivity of the composite dielectric film without affecting the dielectric properties.

[0009] Furthermore, the boron nitride nanosheets have a thickness of 10-100 nm and a lateral dimension of 1-10 μm, and are oriented in the in-plane direction within the matrix resin with an orientation degree ≥0.7. This parameter range ensures that the boron nitride nanosheets form a uniform and continuous oriented thermally conductive network in the matrix resin. An orientation degree ≥0.7 ensures rapid heat conduction in the in-plane direction, avoiding the decrease in thermal conductivity caused by nanofiller agglomeration, while also taking into account the thickness uniformity and mechanical strength of the composite dielectric film.

[0010] Further, the base oil is a synthetic ester oil or silicone oil, with a mass fraction of 85-95%; the thermally conductive nanoparticles are at least one of zinc oxide nanoparticles, silicon carbide nanoparticles, or boron nitride nanoparticles, with a particle size of 20-100 nm and a mass fraction of 5-15%. Synthetic ester oils and silicone oils have excellent insulation properties, temperature resistance, and compatibility, and can serve as dispersion carriers for thermally conductive nanoparticles. The addition of thermally conductive nanoparticles can significantly improve the thermal conductivity of the impregnating agent. Controlling the particle size to 20-100 nm can prevent particle agglomeration, ensuring the fluidity and insulation properties of the impregnating agent. A mass fraction of 5-15% can improve thermal conductivity while avoiding increased dielectric loss due to excessive particles.

[0011] Furthermore, the conductive nanomaterial in the high thermal conductivity electrode interface layer is at least one of carbon nanotubes, graphene, or conductive carbon black, with a mass fraction of 1-10% of the total mass of the electrode interface layer; the organic binder is epoxy resin or polyimide resin. Carbon nanotubes, graphene, and conductive carbon black have excellent electrical and thermal conductivity, and controlling their mass fraction at 1-10% ensures that the electrode interface layer has both conductive and insulating properties, guaranteeing good electrical contact between the electrode and the dielectric film while avoiding interfacial short circuits and reducing contact thermal resistance; epoxy resin and polyimide resin have excellent bonding, insulating, and high-temperature resistance properties, which can firmly fix the conductive nanomaterial at the interface between the electrode and the dielectric film, improving structural stability.

[0012] Furthermore, the thermally conductive and insulating coating comprises a high thermally conductive insulating resin matrix and thermally conductive ceramic particles filled therein, wherein the thermally conductive ceramic particles are alumina or aluminum nitride, with a mass fraction of 20-50%. The high thermally conductive insulating resin matrix ensures the insulation and adhesion properties of the coating, while alumina and aluminum nitride are highly thermally conductive and highly insulating ceramic particles. A mass fraction of 20-50% can significantly improve the thermal conductivity of the coating, while ensuring the insulation properties and mechanical strength of the coating, enabling rapid heat conduction from the inside of the shell to the outside.

[0013] Furthermore, the capacitor casing is further provided with an encapsulation layer, which is a thermally modified epoxy potting compound with a thermal conductivity ≥1.0 W / m·K and a volume resistivity ≥10¹. 4 Ω·cm. Thermally conductive modified epoxy potting compound can comprehensively encapsulate the capacitor case, providing both protection and enhanced heat dissipation. A thermal conductivity ≥1.0 W / m·K ensures the heat dissipation capacity of the encapsulation layer, and a volume resistivity ≥10¹⁰. 4 Ω·cm ensures the insulation performance of the encapsulation layer, preventing any impact on the normal operation of the capacitor.

[0014] Furthermore, the thermally modified epoxy potting compound is composed of the following components by mass fraction: 50-65% epoxy resin, 25-40% boron nitride or alumina filler, 5-10% curing agent, and 1-3% dispersant. The epoxy resin serves as the matrix of the potting compound, providing good adhesion and insulation properties; the boron nitride or alumina filler improves the thermal conductivity of the potting compound; the curing agent ensures that the potting compound can be cured and molded, improving structural stability; and the dispersant prevents filler agglomeration, ensuring the uniformity of the potting compound and the consistency of its thermal conductivity.

[0015] Furthermore, the electrodes of the capacitor core are metallized electrodes with passivation treatment on the electrode surface. The passivation layer is an aluminum oxide or hafnium oxide thin film with a thickness of 5-15 nm. Metallized electrodes have advantages such as light weight, small size, and low internal resistance, making them suitable for high-voltage and high-power applications. The passivation layer can improve the corrosion resistance and oxidation resistance of the electrode, preventing the electrode from oxidizing and failing under high-temperature conditions. At the same time, it further reduces the contact thermal resistance between the electrode and the dielectric film. The thickness of 5-15 nm ensures the passivation effect without affecting the conductivity of the electrode.

[0016] Furthermore, the composite dielectric film has a thickness of 5-50 μm, a thermal conductivity ≥2.5 W / (m·K), a dielectric constant of 2.5-5.0, and a breakdown field strength ≥400 V / μm. This parameter range ensures that the composite dielectric film possesses both excellent thermal conductivity and meets the dielectric and insulation performance requirements of power capacitors. The 5-50 μm thickness adapts to the needs of capacitors with different power ratings and volumes, the thermal conductivity ≥2.5 W / (m·K) enables rapid heat conduction within the core, and the breakdown field strength ≥400 V / μm ensures the safe operation of the capacitor under high-voltage conditions.

[0017] In summary, compared with the prior art, the present invention has the following beneficial technical effects: (1) The heat dissipation efficiency of the present invention is significantly improved. The heat dissipation system is constructed from four levels: inside the capacitor core, between the core and the shell, the shell, and the external encapsulation. The three-dimensional thermally conductive network of the composite dielectric film enables rapid heat conduction inside the core. The nano-composite impregnating agent transfers heat between the core and the shell. The thermally conductive insulating coating accelerates the transfer of heat from inside the shell to the outside. The encapsulation layer further enhances the heat dissipation effect. Compared with the prior art, the operating temperature rise is significantly reduced, which can effectively reduce the operating temperature rise of the capacitor and avoid heat accumulation. (2) This invention takes into account both thermal conductivity and dielectric and insulation properties. The selected high thermal conductivity nanofillers, thermal conductivity nanoparticles, and conductive nanomaterials all have high insulation properties. The mass fraction and parameters of each component have been optimized. While greatly improving heat dissipation performance, it ensures that the core performance of the capacitor, such as dielectric constant and breakdown field strength, meets the requirements of high voltage and high power scenarios, and avoids sacrificing insulation performance in pursuit of heat dissipation performance. (3) The present invention has strong structural stability and long service life. The high thermal conductivity electrode interface layer improves the contact stability between the electrode and the dielectric film, and reduces the contact thermal resistance and contact resistance. The electrode passivation layer improves the corrosion resistance and oxidation resistance of the electrode. The thermally conductive insulating coating and encapsulation layer improve the structural strength and protective performance of the shell, effectively delaying the aging rate of the capacitor and significantly improving the service life compared with the existing capacitor. Attached Figure Description

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

[0019] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention. Example 1

[0020] like Figure 1 As shown, this invention discloses a technical solution: a high-efficiency heat-dissipating power capacitor, the specific structure of which is as follows: It includes a capacitor casing (made of aluminum alloy), a capacitor core disposed inside the casing, and an impregnating agent filled between the capacitor core and the casing; The capacitor core adopts a multilayer composite dielectric film structure, which includes a matrix resin and oriented high thermal conductivity nanofillers to form a three-dimensional thermally conductive network. The matrix resin is biaxially oriented polypropylene (BOPP) with a mass fraction of 85%. The high thermal conductivity nanofillers are boron nitride nanosheets with a mass fraction of 15%. The boron nitride nanosheets are 50 nm thick and 5 μm in lateral dimension, and are oriented in the matrix resin along the in-plane direction with an orientation degree of 0.8. The composite dielectric film has a thickness of 20 μm, a thermal conductivity of 2.8 W / (m·K), a dielectric constant of 3.0, and a breakdown field strength of 420 V / μm. The impregnating agent is a nanocomposite impregnating agent, comprising a base oil and thermally conductive nanoparticles dispersed in the base oil; wherein, the base oil is a synthetic ester oil with a mass fraction of 90%; and the thermally conductive nanoparticles are zinc oxide nanoparticles with a particle size of 50 nm and a mass fraction of 10%. A high thermal conductivity electrode interface layer is provided at the contact interface between the electrode and the dielectric film of the capacitor core. This layer is formed by the composite curing of conductive nanomaterials and organic binders. Among them, the conductive nanomaterials are carbon nanotubes, and the mass fraction is 5% of the total mass of the electrode interface layer; the organic binder is epoxy resin; the thickness of the high thermal conductivity electrode interface layer is 10 μm. The inner wall of the capacitor casing is coated with a thermally conductive insulating coating; the thermally conductive insulating coating includes a high thermally conductive insulating resin matrix (epoxy resin) and thermally conductive ceramic particles (alumina) filled therein, with an alumina mass fraction of 35%; the thickness of the thermally conductive insulating coating is 50μm; The capacitor casing is also equipped with an encapsulation layer, which is a thermally modified epoxy potting compound with a thermal conductivity of 1.2 W / m·K and a volume resistivity of 10 Ω·m. 15 Ω·cm; Thermally conductive modified epoxy potting compound is composed of the following components by mass fraction: epoxy resin 58%, boron nitride filler 32%, curing agent 8%, dispersant 2%; The electrodes of the capacitor core are made of metallized aluminum electrodes, and the electrode surface is passivated. The passivation layer is an aluminum oxide film with a thickness of 10nm.

[0021] The manufacturing process of the capacitor in this embodiment is as follows: 1. Preparation of composite dielectric film: Biaxially oriented polypropylene resin is mixed with boron nitride nanosheets, and an appropriate amount of dispersant is added. The mixture is melt-blended and cast into a film. Then, the boron nitride nanosheets are oriented in-plane by biaxial stretching (stretching temperature 150℃, stretching ratio 3:1). Finally, the film is cured by hot pressing (temperature 150℃, time 30min) to obtain composite dielectric film, which is then cut to the required size for later use. 2. Electrode preparation and passivation: Metallized aluminum electrodes were prepared on the surface of the composite dielectric film by vacuum evaporation, and then the electrode surface was passivated by anodic oxidation to form an aluminum oxide passivation layer. The passivation temperature was 80℃ and the passivation time was 15min. 3. Preparation of high thermal conductivity electrode interface layer: Carbon nanotubes and epoxy resin are mixed, an appropriate amount of solvent is added, and the mixture is stirred evenly to form a composite slurry. The slurry is then coated onto the interface between the electrode and the dielectric film by spraying, and then cured (temperature 140℃, time 30min) to form a high thermal conductivity electrode interface layer. 4. Assembly of capacitor core: The composite dielectric film coated with multiple layers of electrodes and electrode interface layers is stacked and wound to form a capacitor core, and the electrode leads are welded. 5. Shell treatment and coating: Grind, clean and dry the inner wall of the aluminum alloy shell, then apply the thermally conductive and insulating coating slurry (epoxy resin + alumina particles) to the inner wall of the shell, and cure it (temperature 130℃, time 40min) to form a thermally conductive and insulating coating. 6. Impregnation and encapsulation: The capacitor core is placed into the treated shell, a nano-composite impregnating agent is injected, and vacuum degassing is performed (absolute pressure ≤10kPa, time 30min). The shell is then sealed. Then, thermally conductive modified epoxy potting compound is applied to the outside of the shell and cured (temperature 160℃, time 60min) to form an encapsulation layer, resulting in a high-efficiency heat dissipation power capacitor. Example 2

[0022] This embodiment provides a high-efficiency heat dissipation power capacitor, which differs from Embodiment 1 in that: The matrix resin of the composite dielectric film is polyvinylidene fluoride (PVDF), with a mass fraction of 80%; the high thermal conductivity nanofiller is alumina nanofiber, with a mass fraction of 20%; the alumina nanofiber has a diameter of 50 nm and a length of 5 μm, and is oriented in the in-plane direction in the matrix resin with an orientation degree of 0.75; the composite dielectric film has a thickness of 30 μm, a thermal conductivity of 3.2 W / (m·K), a dielectric constant of 4.0, and a breakdown field strength of 450 V / μm; The base oil of the impregnating agent is silicone oil, with a mass fraction of 92%; the thermally conductive nanoparticles are silicon carbide nanoparticles with a particle size of 30 nm and a mass fraction of 8%. The conductive nanomaterial of the high thermal conductivity electrode interface layer is graphene, which accounts for 8% of the total mass of the electrode interface layer; the organic binder is polyimide resin. The thermally conductive ceramic particles in the thermally conductive insulating coating are aluminum nitride, with a mass fraction of 40%. The thermally conductive modified epoxy potting compound consists of the following components by mass fraction: 60% epoxy resin, 30% alumina filler, 7% curing agent, and 3% dispersant; the thermal conductivity of the encapsulation layer is 1.3 W / m·K, and the volume resistivity is 10 Ω·m. 16 Ω·cm; The passivation layer of the electrode is a hafnium oxide thin film with a thickness of 8 nm.

[0023] The preparation process in this embodiment is basically the same as that in Example 1. Only the stretching process of the composite dielectric film (stretching temperature 155℃, stretching ratio 2.5:1), the electrode passivation process (passivation temperature 90℃, passivation time 12min), and the curing parameters of the coating and potting compound are adjusted to ensure the molding quality of each component. Example 3

[0024] This embodiment provides a high-efficiency heat dissipation power capacitor, which differs from Embodiment 1 in that: The matrix resin of the composite dielectric film is biaxially oriented polypropylene (BOPP) with a mass fraction of 75%; the high thermal conductivity nanofiller is boron nitride nanosheets with a mass fraction of 25%; the boron nitride nanosheets have a thickness of 100 nm, a lateral dimension of 10 μm, and an alignment degree of 0.9; the composite dielectric film has a thickness of 50 μm, a thermal conductivity of 3.5 W / (m·K), a dielectric constant of 2.5, and a breakdown field strength of 480 V / μm. The impregnating agent consists of boron nitride nanoparticles with a particle size of 100 nm and a mass fraction of 15%; the base oil is a synthetic ester oil with a mass fraction of 85%. The conductive nanomaterial of the high thermal conductivity electrode interface layer is conductive carbon black, with a mass fraction of 10% of the total mass of the electrode interface layer; The thermally conductive ceramic particles in the thermally conductive insulating coating are alumina, with a mass fraction of 50%. The thermally conductive modified epoxy potting compound consists of the following components by mass fraction: 50% epoxy resin, 40% boron nitride filler, 8% curing agent, and 2% dispersant; the thermal conductivity of the encapsulation layer is 1.5 W / m·K, and the volume resistivity is 10 Ω·m. 14 Ω·cm; The passivation layer of the electrode is an aluminum oxide thin film with a thickness of 15 nm. Example 4

[0025] This embodiment provides a high-efficiency heat dissipation power capacitor, which differs from Embodiment 1 in that: The matrix resin of the composite dielectric film is polyvinylidene fluoride (PVDF), with a mass fraction of 90%; the high thermal conductivity nanofiller is alumina nanofiber, with a mass fraction of 10%; the alumina nanofiber has a diameter of 30 nm, a length of 3 μm, and an orientation degree of 0.7; the composite dielectric film has a thickness of 10 μm, a thermal conductivity of 2.6 W / (m·K), a dielectric constant of 5.0, and a breakdown field strength of 400 V / μm; The impregnating agent contains thermally conductive nanoparticles, which are a mixture of zinc oxide and silicon carbide nanoparticles (mass ratio 1:1), with a particle size of 20 nm and a mass fraction of 5%; the base oil is silicone oil with a mass fraction of 95%. The conductive nanomaterial of the high thermal conductivity electrode interface layer is a mixture of carbon nanotubes and graphene (mass ratio 2:1), with a mass fraction of 1% of the total mass of the electrode interface layer; The thermally conductive ceramic particles in the thermally conductive insulating coating are aluminum nitride, with a mass fraction of 20%. The thermally conductive modified epoxy potting compound consists of the following components by mass fraction: 65% epoxy resin, 25% alumina filler, 8% curing agent, and 2% dispersant; the thermal conductivity of the encapsulation layer is 1.0 W / m·K, and the volume resistivity is 10 Ω·m. 15 Ω·cm; The passivation layer of the electrode is a hafnium oxide thin film with a thickness of 10 nm.

[0026] Comparative Example 1: This comparative example provides a conventional power capacitor, which differs from Example 1 in that: The composite dielectric film is a single biaxially oriented polypropylene film without high thermal conductivity nanofillers. Its thermal conductivity is 0.6 W / (m·K) and its breakdown field strength is 380 V / μm. The impregnating agent is a common synthetic ester oil, which contains no thermally conductive nanoparticles and has a thermal conductivity of 0.15 W / (m·K). There is no highly thermally conductive electrode interface layer at the contact interface between the electrode and the dielectric film. The inner wall of the capacitor casing has no thermally conductive insulating coating; The capacitor casing has no external encapsulation layer; The electrode surface is not passivated.

[0027] The preparation process of this comparative example is the same as that of Example 1, except that it does not involve the addition of high thermal conductivity nanofillers, preparation of electrode interface layers, coating, and encapsulation.

[0028] Comparative Example 2: This comparative example provides a power capacitor, which differs from Example 1 in that: there is no high thermal conductivity electrode interface layer at the contact interface between the electrode and the dielectric film of the capacitor core, while the rest of the structure and manufacturing process are completely consistent with Example 1.

[0029] Comparative Example 3: This comparative example provides a power capacitor, which differs from Example 1 in that the impregnating agent is a common synthetic ester oil, without thermally conductive nanoparticles, while the remaining structure and preparation process are completely consistent with Example 1.

[0030] Comparative Example 4: This comparative example provides a power capacitor, which differs from Example 1 in that: the inner wall of the capacitor casing has no thermally conductive insulating coating, while the rest of the structure and manufacturing process are completely consistent with Example 1.

[0031] Comparative Example 5: This comparative example provides a power capacitor, which differs from Example 1 in that the boron nitride nanosheets in the composite dielectric film are non-directionally arranged (without biaxial stretching process), and the degree of orientation is 0.3. The remaining structure and preparation process are completely consistent with Example 1.

[0032] Performance testing and results analysis: Test sample Thermal conductivity of composite dielectric thin films [W / (m·K)] Thermal conductivity of impregnating agent [W / (m·K)] Operating temperature rise [°C] Dielectric constant Breakdown electric field strength [V / μm] <![CDATA[Loss tangent tanδ (×10- 4 )]]> Insulation resistance [Ω] Service life (years) Example 1 2.8 0.45 18 3.0 420 8.5 <![CDATA[8.5×10 11 ]]> 15.5 Example 2 3.2 0.42 16 4.0 450 9.2 <![CDATA[7.8×10 11 ]]> 16.8 Example 3 3.5 0.50 15 2.5 480 8.0 <![CDATA[9.2×10 11 ]]> 16.2 Example 4 2.6 0.38 20 5.0 400 9.0 <![CDATA[8.3×10 11 ]]> 15.0 Comparative Example 1 0.6 0.15 42 2.2 380 6.5 <![CDATA[1.2×10 11 ]]> 8.5 Comparative Example 2 2.8 0.45 28 3.0 410 8.8 <![CDATA[8.0×10 11 ]]> 12.5 Comparative Example 3 2.8 0.15 32 3.0 415 8.6 <![CDATA[8.2×10 11 ]]> 11.0 Comparative Example 4 2.8 0.45 30 3.0 420 8.5 <![CDATA[8.4×10 11 ]]> 13.0 Comparative Example 5 1.2 0.45 25 3.0 405 9.5 <![CDATA[7.5×10 11 ]]> 12.0 The power capacitors of Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests. The test items included: thermal conductivity (composite dielectric film, impregnating agent, thermally conductive insulating coating, encapsulation layer), capacitor operating temperature rise, dielectric constant, breakdown field strength, loss tangent, insulation resistance, and service life. The test methods are as follows: 1. Thermal conductivity test: The thermal conductivity of composite dielectric film, thermally conductive insulating coating and encapsulation layer is tested by hot wire method (according to GB / T 10294-2008); the thermal conductivity of impregnating agent is tested by steady-state plate method (according to GB / T 22588-2008). 2. Temperature rise test during operation: Place the capacitor in a constant temperature environment of 25℃, apply the rated voltage (10kV), and run continuously for 24 hours. Use an infrared thermometer to test the highest temperature of the capacitor casing and calculate the temperature rise (highest temperature - ambient temperature). 3. Dielectric constant test: According to GB / T 1409-2006, the dielectric constant of the composite dielectric film is tested at a frequency of 1kHz; 4. Breakdown field strength test: According to GB / T 1408.1-2016, the breakdown field strength of the composite dielectric film is tested using a breakdown voltage tester. 5. Loss tangent test: According to GB / T 1409-2006, the loss tangent (tanδ) of the capacitor is tested at a frequency of 1kHz and at the rated voltage. 6. Insulation resistance test: According to GB / T 11024.1-2019, apply a voltage of 500VDC and read the insulation resistance value after 1 minute; 7. Service life test: Accelerated aging test (according to GB / T 11024.1-2019) is adopted. The capacitor is placed in a constant temperature environment of 85℃ and the rated voltage is applied to test the service life of the capacitor (failure criterion: capacitance decay of more than 10% or breakdown).

[0033] The test results are shown in the table below: Results analysis: 1. As can be seen from the test results of Examples 1-4, the high-efficiency heat dissipation power capacitor provided by the present invention has a composite dielectric film thermal conductivity ≥2.5W / (m·K), an impregnating agent thermal conductivity ≥0.38W / (m·K), an operating temperature rise ≤20℃, a dielectric constant of 2.5-5.0, a breakdown field strength ≥400V / μm, and a loss tangent ≤10×10⁻⁶. -4 Insulation resistance ≥10 11 Ω, all with a service life of ≥15 years, and excellent performance in all aspects, enabling efficient heat dissipation and stable operation.

[0034] 2. Comparing Example 1 with Comparative Example 1 (existing conventional capacitor), the thermal conductivity of the composite dielectric film of the present invention is increased by 367%, the thermal conductivity of the impregnating agent is increased by 200%, the operating temperature rise is reduced by 57%, and the service life is increased by 82%. This fully demonstrates that the end-to-end heat dissipation system of the present invention can significantly improve heat dissipation efficiency, extend the service life of the capacitor, and at the same time ensure dielectric and insulation performance.

[0035] 3. Comparing Example 1 with Comparative Examples 2-5, the absence of a high thermal conductivity electrode interface layer, nanocomposite impregnating agent, thermally conductive insulating coating, or non-directional arrangement of nanofillers all lead to increased operating temperature rise and shortened service life of the capacitor. Among them, the absence of nanocomposite impregnating agent has the most significant impact (the temperature rise of Comparative Example 3 is 78% higher than that of Example 1). Non-directional arrangement of nanofillers leads to a significant decrease in the thermal conductivity of the composite dielectric film (the thermal conductivity of Comparative Example 5 is only 43% of that of Example 1). This further illustrates the synergistic effect of the various technical features of the present invention. None of them can be omitted, forming a complete end-to-end heat dissipation system with significant technical advantages.

[0036] 4. Example 2 has the best overall performance. Its composite dielectric film uses PVDF matrix + alumina nanofiber, the electrode interface layer uses graphene, and the potting compound has a high thermal conductivity, resulting in an operating temperature rise of only 16°C and a service life of 16.8 years. This shows that by optimizing the types and parameters of each component, the performance of the capacitor can be further improved.

[0037] 5. In terms of insulation performance, the loss tangent and insulation resistance of the capacitor of this invention both meet the requirements of the power capacitor industry standard (tanδ≤10×10). -4 Insulation resistance ≥10 11 The result (Ω) indicates that the addition of highly thermally conductive nanofillers did not negatively affect the electrical performance, and that the thermal conductivity and insulation properties were well balanced.

[0038] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-efficiency heat-dissipating power capacitor, comprising a capacitor casing, a capacitor core disposed inside the casing, and an impregnating agent filled between the capacitor core and the casing, characterized in that: The capacitor core adopts a multilayer composite dielectric film structure, which includes a matrix resin and oriented highly thermally conductive nanofillers to form a three-dimensional thermally conductive network. The impregnating agent is a nanocomposite impregnating agent, comprising base oil and thermally conductive nanoparticles dispersed in the base oil; A high thermal conductivity electrode interface layer is provided at the contact interface between the electrode and the dielectric film of the capacitor core. This layer is formed by the composite curing of conductive nanomaterials and organic binders. The inner wall of the capacitor casing is coated with a thermally conductive and insulating coating.

2. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The matrix resin is biaxially oriented polypropylene or polyvinylidene fluoride, with a mass fraction of 75-90%. The high thermal conductivity nanofiller is boron nitride nanosheets or alumina nanofibers, with a mass fraction of 10-25%.

3. The high-efficiency heat dissipation power capacitor according to claim 2, characterized in that: The boron nitride nanosheets have a thickness of 10-100 nm and a lateral dimension of 1-10 μm. They are oriented in the in-plane direction in the matrix resin with an orientation degree ≥0.

7.

4. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The base oil is a synthetic ester oil or silicone oil, with a mass fraction of 85-95%. The thermally conductive nanoparticles are at least one of zinc oxide nanoparticles, silicon carbide nanoparticles, or boron nitride nanoparticles, with a particle size of 20-100 nm and a mass fraction of 5-15%.

5. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The conductive nanomaterial in the high thermal conductivity electrode interface layer is at least one of carbon nanotubes, graphene, or conductive carbon black, and its mass fraction is 1-10% of the total mass of the electrode interface layer; The organic binder is epoxy resin or polyimide resin.

6. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The thermally conductive insulating coating comprises a high thermally conductive insulating resin matrix and thermally conductive ceramic particles filled therein, wherein the thermally conductive ceramic particles are alumina or aluminum nitride, with a mass fraction of 20-50%.

7. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The capacitor casing is further provided with an encapsulation layer, which is a thermally modified epoxy potting compound with a thermal conductivity ≥1.0 W / m·K and a volume resistivity ≥10¹. 4 Ω·cm.

8. The high-efficiency heat dissipation power capacitor according to claim 7, characterized in that: The thermally conductive modified epoxy potting compound is composed of the following components by mass fraction: 50-65% epoxy resin, 25-40% boron nitride or alumina filler, 5-10% curing agent, and 1-3% dispersant.

9. The high-efficiency heat dissipation power capacitor according to claim 1, characterized in that: The electrodes of the capacitor core are metallized electrodes, and the electrode surface is passivated. The passivation layer is an aluminum oxide or hafnium oxide thin film with a thickness of 5-15 nm.

10. A high-efficiency heat-dissipating power capacitor according to claim 1, characterized in that: The composite dielectric film has a thickness of 5-50 μm, a thermal conductivity ≥2.5 W / (m·K), a dielectric constant of 2.5-5.0, and a breakdown field strength ≥400 V / μm.

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