Efficient ripple current aluminum electrolytic capacitor module for photovoltaic inverter

Abstract

The invention relates to the technical field of photovoltaic inverters, in particular to an efficient ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, which comprises a plurality of capacitor modules arranged on a circuit board in parallel, and each capacitor module comprises an aluminum electrolytic capacitor unit and a distributed heat dissipation structure; the aluminum electrolytic capacitor unit is composed of a high-purity aluminum foil, a mixed electrolyte and a high-temperature-resistant sealing shell; the distributed heat dissipation structure is formed by compounding an aluminum fin and a nano ceramic coating substrate, and is attached to the surface of the aluminum electrolytic capacitor unit shell in a spiral shape. According to the invention, the ethylene glycol-based electrolyte and the ionic liquid are compounded, and the nano aluminum oxide particles are added to form an ion rapid channel, so that electrolyte polarization suppression and ion mobility improvement are completed, namely, the ripple current endurance capability is improved; through the composite design of the aluminum fins and the V-shaped diversion trenches, the turbulence intensity of airflow is improved, the interface thermal resistance is reduced, and the effect of reducing temperature rise under the same heat dissipation area is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic inverters, and particularly to a high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter. Background Art

[0002] An inverter, also known as a power conditioner, is a power conditioning device composed of semiconductor devices. It is mainly used to convert DC power into AC power. Generally, the ripple current flowing through the electrolytic capacitor in a photovoltaic inverter is relatively high. In this case, if the rated ripple current of a single electrolytic capacitor cannot meet the requirements, multiple electrolytic capacitors need to be connected in parallel to obtain the required current value. Therefore, it is required that the single electrolytic capacitor has a high ripple tolerance to reduce the number of parallel-connected electrolytic capacitors and improve the overall reliability.

[0003] Traditional aluminum electrolytic capacitors may have serious heat generation and short lifespan under high ripple current, or be too large in size, which is not suitable for the compact design of photovoltaic inverters. In addition, a photovoltaic system may be outdoors with large temperature variations, requiring better temperature stability. Summary of the Invention

[0004] In order to overcome the defects in the prior art, the purpose of the present invention is to provide a high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides a high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, including an inverter housing and a circuit board installed therein. A plurality of capacitor modules are arranged in parallel on the circuit board. Each capacitor module includes an aluminum electrolytic capacitor unit and a distributed heat dissipation structure attached to the outer wall of the aluminum electrolytic capacitor unit.

[0006] The aluminum electrolytic capacitor unit is composed of high-purity aluminum foil, a hybrid electrolyte, and a high-temperature resistant sealing housing. An adaptive voltage equalization circuit is integrated inside the aluminum electrolytic capacitor unit, which includes a dynamic impedance matching module and a voltage feedback controller.

[0007] The distributed heat dissipation structure is composed of an aluminum fin and a nano-ceramic coating substrate, and is spirally attached to the surface of the aluminum electrolytic capacitor unit housing.

[0008] A temperature monitoring system is arranged inside the inverter housing, which includes an embedded temperature sensor and an active cooling controller, and is communicatively connected to the inverter main control system.

[0009] As a further improvement of this technical solution, the hybrid electrolyte is a mixture of ethylene glycol-based electrolyte and ionic liquid in a volume ratio of 7:3, and 0.5 - 1.2 wt% of nano-aluminum oxide particles are added.

[0010] As a further improvement of the technical solution, the high-temperature resistant sealed housing is co-injection molded from polyphenylene sulfide and carbon fiber reinforced composite material, and the wall thickness of the housing is 1.2 - 1.8 mm.

[0011] As a further improvement of the technical solution, the nano-ceramic coated substrate is formed by plasma spraying from Al 2 O 3 -ZrO 2 composite ceramic material, with a thickness of 50 - 80 μm and a thermal conductivity ≥ 25 W / m·K.

[0012] As a further improvement of the technical solution, the surface of the aluminum fin is provided with micro-meter level diversion grooves, one side wall of the inverter housing is provided with a heat dissipation port, and the aluminum electrolytic capacitor unit is close to the heat dissipation port.

[0013] As a further improvement of the technical solution, the diversion grooves are formed by arranging a number of V-shaped unit grooves in a staggered manner along the surface of the aluminum fin into several rows. The groove depth of the V-shaped unit groove is 0.2 - 0.5 mm, the opening angle of the V-shaped unit groove is 60° - 90°, and the radius of the fillet at the bottom of the groove R ≤ 50 μm.

[0014] As a further improvement of the technical solution, each adjacent V-shaped unit groove in each row of the diversion grooves is in a mirror symmetry relationship. The vertex spacing between two adjacent V-shaped unit grooves is 1.0 - 1.5 mm, and there is a lateral offset between several V-shaped unit grooves in the upper and lower layers, forming a continuous staggered wavy flow channel.

[0015] As a further improvement of the technical solution, the dynamic impedance matching module includes a fast switching circuit based on IGBT and a ripple frequency detection unit, and the response time ≤ 10 μs.

[0016] As a further improvement of the technical solution, the temperature monitoring system dynamically adjusts the cooling strategy through a predictive life algorithm, and the algorithm inputs include the effective value of the ripple current, the ambient temperature, and the historical working time.

[0017] As a further improvement of the technical solution, it further includes a modular interface for supporting the quick plugging and unplugging of the aluminum electrolytic capacitor unit; the modular interface adopts a three-contact elastic connection structure, including a power contact, a signal contact, and a ground contact, and the plugging and unplugging life ≥ 5000 times.

[0018] Compared with the prior art, the beneficial effects of the present invention:

[0019] 1. The high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter combines nano-composite electrolyte, dynamic voltage equalization control, and predictive thermal management. It forms a closed-loop optimization in cooperation with the capacitor module and the inverter control system. By compounding ethylene glycol-based electrolyte with ionic liquid and adding nano-aluminum oxide particles to form an ion rapid channel, it inhibits electrolyte polarization and improves ion mobility, achieving the effect of reducing the electron spin resonance spectroscopy test and facilitating the improvement of the ripple current tolerance.

[0020] 2. The high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, through the composite design of aluminum fins and V-shaped flow guide grooves, combined with a gradient-deepening nano-ceramic substrate, improves the air flow turbulence intensity and reduces the interface thermal resistance, achieving the effect of reducing the temperature rise under the same heat dissipation area and enhancing the ability to operate continuously in a high-temperature environment.

[0021] 3. The high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, by setting a dynamic impedance matching module to detect the ripple frequency in real time and adjusting the impedance of the parallel branches with the rapid switching of IGBT, achieves the dynamic balance of the current of each capacitor unit, and has the effects of improving the current unevenness and extending the overall service life of the module. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. Additionally, the shapes and proportional dimensions of the components in the drawings are only schematic for facilitating the understanding of the present invention and do not specifically limit the shapes and proportional dimensions of the components of the present invention. Those skilled in the art, under the teaching of the present invention, can select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention.

[0023] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 is a schematic diagram of the assembly structure of the circuit board and the capacitor module of the present invention;

[0025] Figure 3 is a schematic diagram of the flattened and enlarged structure of the aluminum fins of the present invention;

[0026] The meanings of the various reference numerals in the drawings are as follows:

[0027] 100, inverter housing; 101, heat dissipation port; 110, circuit board;

[0028] 200, capacitor module; 210, aluminum electrolytic capacitor unit; 220, aluminum fins; 221, flow guide groove. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Combined with the accompanying drawings and the description of the specific embodiments of the present invention, the details of the present invention can be more clearly understood. However, the specific embodiments of the present invention described herein are only for the purpose of explaining the present invention and cannot be construed in any way as a limitation of the present invention. Under the teaching of the present invention, the concepts of those skilled in the art are based on any possible variations of the present invention, and these should all be regarded as belonging to the scope of the present invention. The terms "installation" and "connection" should be understood in a broad sense, which can be directly connected or indirectly connected through an intermediate medium.

[0030] The terms "central axis", "vertical", "horizontal", "front", "rear", "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", etc. used herein indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, so they cannot be understood as a limitation of the present invention. In addition, in the description of the present invention, the meaning of "several" is two or more, unless otherwise specifically defined.

[0031] Please refer to Figures 1 - 3 As shown, the present invention provides an efficient ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, which includes an inverter housing 100 and a circuit board 110 installed therein. A plurality of capacitor modules 200 are arranged in parallel on the circuit board 110. The capacitor module 200 includes an aluminum electrolytic capacitor unit 210 and a distributed heat dissipation structure attached to the outer wall of the aluminum electrolytic capacitor unit 210;

[0032] The aluminum electrolytic capacitor unit 210 is composed of high-purity aluminum foil, a hybrid electrolyte, and a high-temperature resistant sealing housing; an adaptive voltage equalization circuit is integrated inside the aluminum electrolytic capacitor unit 210, which includes a dynamic impedance matching module and a voltage feedback controller;

[0033] The distributed heat dissipation structure is composed of an aluminum fin 220 and a nano-ceramic coating substrate, and is spirally attached to the surface of the housing of the aluminum electrolytic capacitor unit 210;

[0034] Among them, a temperature monitoring system is arranged inside the inverter housing 100, which includes an embedded temperature sensor and an active cooling controller, and is communicatively connected to the inverter main control system.

[0035] Specifically, the hybrid electrolyte is a mixture of ethylene glycol-based electrolyte and ionic liquid in a volume ratio of 7:3, and 0.5 - 1.2 wt% of nano-aluminum oxide particles are added; it is used to improve the high-frequency ripple current absorption ability, reduce the equivalent series resistance, and increase the operating temperature range.

[0036] Among them, the ripple current absorption: The parallel aluminum electrolytic capacitor unit 210 quickly responds to high-frequency ripple current through the high ionic mobility of the mixed electrolyte, and the nano-aluminum oxide particles inhibit the polarization of the electrolyte.

[0037] Dynamic voltage sharing control: The voltage feedback controller monitors the voltage of each unit in real time, and adjusts the impedance of the parallel branch through IGBT switching to ensure the even distribution of current.

[0038] Intelligent heat dissipation management: The data of the temperature sensor is input into the prediction algorithm, and when a hot spot is detected, forced air cooling is started or the inverter switching frequency is reduced.

[0039] Specifically, the high-temperature resistant sealed housing is co-injected and molded from polyphenylene sulfide and carbon fiber reinforced composite material, and the wall thickness of the housing is 1.2 - 1.8 mm; it is used to increase the bending strength and reduce the leakage situation in an environment of 85°C / 85% RH; it passes the high-pressure steam sterilization test according to the JEDEC JESD22-A102 standard; the bending strength test is based on the ISO 178 standard; data requirements: the deformation of the housing is < 0.05 mm after 500 hours of high-pressure steam sterilization; the bending modulus is 320 MPa, which is improved compared with the traditional PP material ≤ 200 MPa.

[0040] Further, the nano-ceramic coated substrate is made of Al 2 O 3 -ZrO 2 The composite ceramic material is formed by plasma spraying, with a thickness of 50 - 80 μm and a thermal conductivity ≥ 25 W / m·K; it is used for efficient heat conduction between the capacitor unit and the heat dissipation structure to reduce the interface thermal resistance; the interface thermal resistance test is carried out according to the ASTM D5470 standard; the coating adhesion test is carried out according to the ASTM C633 standard.

[0041] Specifically, the surface of the aluminum fin is provided with a micro-scale flow guiding groove 221, a heat dissipation port 101 is opened on one side wall of the inverter housing 100, and the aluminum electrolytic capacitor unit 210 is close to the heat dissipation port 101; the flow guiding groove 221 is formed by arranging a number of V-shaped unit grooves in a staggered manner along the surface of the aluminum fin 220 into several rows, the groove depth of the V-shaped unit groove is 0.2 - 0.5 mm, the opening angle of the V-shaped unit groove is 60° - 90°, and the radius of the fillet at the bottom of the groove R ≤ 50 μm; in this way, a turbulent flow effect is formed to strengthen heat dissipation, and the heat dissipation efficiency is improved under the same air volume.

[0042] Each row of adjacent V-shaped unit grooves in the diversion groove 221 is in a mirror symmetry relationship. The vertex spacing between two adjacent V-shaped unit grooves is 1.0 - 1.5 mm. There is a lateral offset between several V-shaped unit grooves in the upper and lower layers, forming a continuous staggered wavy flow channel, which is used to increase the heat dissipation area, improve the air flow disturbance efficiency, and thus the heat dissipation capacity is better than that of traditional flat fins under the same volume. Through the wind tunnel heat dissipation efficiency test, the wind speed is 2 m / s and the ambient temperature is 40 °C. Mechanical vibration test is carried out according to the IEC60068-2-6, 10 - 2000 Hz standard.

[0043] Specifically, the turbulence excitation mechanism: The staggered convex structures of several V-shaped unit grooves cause the air flow to generate horseshoe vortices, and the ratio of the longitudinal spacing to the groove depth is ensured to fully develop the vortices.

[0044] Experimental verification data:

[0045] 1. CFD simulation results (ANSYS Fluent) Parameter Traditional straight groove V-shaped staggered groove Lifting amplitude Heat dissipation coefficient (W / m²·K) 128 189 +47.7% Turbulence intensity (%) 18.2 29.5 +62.1% Pressure drop (Pa) 42 38 -9.5%

[0046] 2. Infrared thermal imaging measured data

[0047] Test conditions: Input power density: 2 W / cm², forced air cooling wind speed: 2.5 m / s;

[0048] Result comparison:

[0049] The highest temperature point: Traditional straight groove 82 °C → V-shaped staggered groove 67 °C, a decrease of 18.3%;

[0050] Temperature uniformity (σ value): 3.2 °C → 1.8 °C, an increase of 43.8%;

[0051] Among them, the key points of the manufacturing process of the aluminum fin 220 are precision stamping: using carbide dies (HRC≥62), stamping speed: 200 - 300 times / minute, positioning accuracy: ±5 μm;

[0052] Surface post-treatment: Electrochemical polishing to remove burrs, current density 10 A / dm², anodic oxidation to generate a 5-μm alumina insulation layer;

[0053] Quality inspection: Measuring the consistency of the groove depth with a white light interferometer, CPK≥1.33, and verifying the flow field distribution by particle image velocimetry (PIV).

[0054] Furthermore, the dynamic impedance matching module includes a fast switching circuit based on IGBT and a ripple frequency detection unit, with a response time ≤10 μs; dynamically balancing the current distribution of each aluminum electrolytic capacitor unit 210 to control the ripple current non-uniformity.

[0055] Furthermore, the temperature monitoring system dynamically adjusts the cooling strategy through a predictive life algorithm. The algorithm inputs include the effective value of the ripple current, the ambient temperature, and the historical working time, which improves the life prediction accuracy and actively prevents the risk of thermal runaway.

[0056] In addition, it also includes a modular interface for supporting the quick plugging and unplugging of the aluminum electrolytic capacitor unit 210. The modular interface adopts a three-contact elastic connection structure, including a power contact, a signal contact, and a ground contact. The plugging and unplugging life is ≥5000 times. It passes the plugging and unplugging force cycle test according to the MIL-STD-1344 standard and the salt spray corrosion test according to the IEC 60068-2-52 standard. Data requirements: the change rate of the contact resistance after the 5000th plugging and unplugging is <1.5%; the corrosion area of the contact after 96 hours of salt spray test is <3%; it ensures that the contact resistance is stable below 1mΩ in a high-vibration environment and supports hot plugging and replacement.

[0057] It should be noted that the above embodiments are only for explaining the technical concept and features of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A high-efficiency ripple current aluminum electrolytic capacitor module for a photovoltaic inverter, comprising an inverter housing (100) and a circuit board (110) installed therein, characterized in that: A plurality of capacitor modules (200) are arranged in parallel on the circuit board (110), wherein the capacitor module (200) comprises an aluminum electrolytic capacitor unit (210) and a distributed heat dissipation structure attached to the outer wall of the aluminum electrolytic capacitor unit (210); The aluminum electrolytic capacitor unit (210) is composed of high-purity aluminum foil, a mixed electrolyte and a high-temperature resistant sealed housing; an adaptive voltage balancing circuit is integrated inside the aluminum electrolytic capacitor unit (210), which includes a dynamic impedance matching module and a voltage feedback controller; The distributed heat dissipation structure is formed by combining an aluminum fin (220) and a nano-ceramic coating substrate, and is adhered to the shell surface of the aluminum electrolytic capacitor unit (210) in a spiral shape; A temperature monitoring system is provided in the inverter housing (100), comprising an embedded temperature sensor and an active cooling controller, and is communicatively connected to the inverter main control system.

2. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 1, characterized in that: The mixed electrolyte is prepared by mixing an ethylene glycol-based electrolyte and an ionic liquid in a volume ratio of 7:3, and adding 0.5-1.2 wt % of nano-alumina particles.

3. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 2, characterized in that: The high temperature resistant sealed shell is co-injected by polyphenylene sulfide and carbon fiber reinforced composite material, and the shell wall thickness is 1.2-1.8 mm.

4. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 3, characterized in that: The nano ceramic coating substrate is formed by plasma spraying of Al2O3-ZrO2 composite ceramic material, has a thickness of 50-80 μm, and a thermal conductivity of ≥25 W / m·K.

5. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 4, characterized in that: The surface of the aluminum fin is provided with a micrometer-sized flow guide groove (221), a side wall of the inverter housing (100) is provided with a heat dissipation port (101), and the aluminum electrolytic capacitor unit (210) is close to the heat dissipation port (101).

6. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 5, characterized in that: The guide grooves (221) are composed of a plurality of V-shaped unit grooves arranged in a staggered manner in a plurality of rows along the surface of the aluminum fin (220), the groove depth of the V-shaped unit groove is 0.2-0.5 mm, the opening angle of the V-shaped unit groove is 60°-90°, and the groove bottom fillet radius R is ≤50 μm.

7. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 6, characterized in that: Each row of adjacent V-shaped unit grooves of the guide groove (221) is in a mirror-symmetrical relationship, wherein the distance between the vertices of two adjacent V-shaped unit grooves is 1.0-1.5 mm, and a plurality of V-shaped unit grooves in the upper and lower layers have a lateral offset, forming a continuous staggered wavy flow channel.

8. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 7, characterized in that: The dynamic impedance matching module includes an IGBT-based fast switching circuit and a ripple frequency detection unit, and the response time is ≤10 μs.

9. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 8, characterized in that: The temperature monitoring system dynamically adjusts the cooling strategy through a predictive life algorithm, and the algorithm input includes the effective value of the ripple current, the ambient temperature and the historical working time.

10. The high-efficiency ripple current aluminum electrolytic capacitor module for photovoltaic inverter according to claim 9, characterized in that: It also includes a modular interface for supporting the rapid plugging and unplugging of the aluminum electrolytic capacitor unit (210); the modular interface adopts a three-contact elastic connection structure, including a power contact, a signal contact and a ground contact, and has a plugging and unplugging life of ≥5000 times.

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