A positive temperature coefficient composite ceramic capacitor

Abstract

The present invention relates to the technical field of ceramic capacitors, and particularly relates to a composite ceramic capacitor with a positive temperature coefficient, which includes a high-voltage conductive rod. The high-voltage conductive rod has a cylindrical structure, and a support flange is coaxially installed on the outer side of the high-voltage conductive rod. Ceramic capacitor elements are installed in parallel on the support flange. By installing ceramic capacitor elements in parallel on the support flange outside the high-voltage conductive rod, the present invention significantly reduces the overall temperature coefficient of the composite ceramic capacitor while improving the strength of the composite ceramic capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic capacitors, and particularly to a composite ceramic capacitor with a positive temperature coefficient. Background Art

[0002] A capacitor is an electronic component that stores electrical energy in an electric field. The basic structure of a capacitor consists of two conductor plates and an insulating medium sandwiched between the conductor plates. When the two conductor plates of the capacitor are connected to a power supply, positive and negative charges accumulate on the two conductor plates respectively, and electrical energy is stored in the form of an electric field formed; when the two conductor plates of the capacitor are disconnected from the power supply, the charges on the two conductor plates are released through an external circuit, and the electrical energy is converted into other forms of energy such as light energy, heat energy, and kinetic energy. Capacitors can be classified into paper capacitors, film capacitors, ceramic capacitors, electrolytic capacitors, and other dielectric capacitors according to the insulating medium. Among them, ceramic capacitors with a negative temperature coefficient have the characteristics of small volume, low cost, and high energy density, but their temperature stability is poor, and the capacitance value may be too small in a low-temperature environment; film capacitors have the characteristics of light weight and stable performance, and are often used as voltage-dividing elements of capacitive voltage transformers with high voltage levels. However, the absolute value of the temperature coefficient of film capacitors is relatively large, the capacitance value decreases significantly when the temperature rises, the voltage division ratio is greatly affected by temperature, there is a large amount of residual inductance, which hinders the transmission of high-frequency overvoltage and is prone to local overvoltage breakdown. When a film capacitor is applied to a gas capacitive current transformer product, when the film capacitor is combined with a high-voltage coaxial electrode capacitor, there are problems of mismatched temperature coefficients, poor error accuracy, and inability to meet the accuracy specification requirements under extreme temperatures and specified loads. Moreover, with a coaxial winding structure, the mechanical strength is low and there is a risk of slippage. Summary of the Invention

[0003] Aiming at the problem of mismatched temperature coefficients when a film capacitor is used in combination with a high-voltage coaxial electrode capacitor, the present invention provides a composite ceramic capacitor with a positive temperature coefficient. By installing ceramic capacitor elements in parallel on the support flange outside the high-voltage conductive rod, while improving the strength of the composite ceramic capacitor, the overall temperature coefficient of the composite ceramic capacitor is significantly reduced.

[0004] The technical solution of the present invention is as follows:

[0005] A composite ceramic capacitor with a positive temperature coefficient includes a high-voltage conductive rod. The high-voltage conductive rod has a cylindrical structure. A support flange is coaxially installed outside the high-voltage conductive rod. Multiple sets of ceramic capacitor elements are assembled on the support flange. The multiple sets of ceramic capacitor elements are connected in parallel with each other, and the overall temperature coefficient of the multiple sets of ceramic capacitor elements is positive. The voltage of the high-voltage conductive rod is 0 - 120 kV.

[0006] Furthermore, four groups of support flange mounting positions are coaxially arranged on the outer side of the high-voltage conductive rod along the length direction, and each group of support flange mounting positions includes four mounting seats, and the four mounting seats are circumferentially distributed on the outer side of the high-voltage conductive rod at equal intervals along the axis of the high-voltage conductive rod.

[0007] Furthermore, screw holes are provided on the mounting base, and the screw holes on each mounting base are all oriented toward the same end of the high-voltage conductive rod.

[0008] Furthermore, the support flange includes an annular mounting plate, which is a ring-shaped structure. Four fixing parts are arranged on the inner side of the annular mounting plate. The four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting plate. The fixing parts are threadedly connected to the mounting seat. Multiple groups of capacitor mounting positions are arranged on the outer side of the annular mounting plate. Ceramic capacitor elements are installed on each group of capacitor mounting positions. The ceramic capacitor elements are single-layer ceramic capacitors.

[0009] Furthermore, the ceramic capacitor element includes an epoxy resin shell, and two ceramic capacitor cores are encapsulated inside the epoxy resin shell. The present invention adopts an epoxy resin encapsulation process to control the capacitance deviation of the combined ceramic capacitor within the range of ±2%. The upper end face and the lower end face of the ceramic capacitor core are respectively welded with inserts. The upper end face inserts of the two ceramic capacitor cores after combination are connected to the low-voltage electrode, and the lower end face inserts of the two ceramic capacitor cores after combination are connected to the high-voltage conductive rod. The two ceramic capacitor cores in the same ceramic capacitor element are connected in parallel to achieve the required capacitance; the corresponding insulation distance is maintained between the lower end face inserts of the two ceramic capacitor cores in the same ceramic capacitor element; the outer surface of the ceramic capacitor core is coated with a black glass glaze layer, and the thickness of the black glass glaze layer is 0.2-0.5mm.

[0010] Furthermore, the preparation method of the ceramic capacitor element includes the following steps:

[0011] Step (1): Place the ceramic capacitor core into a mold and dry it at 120-140°C for more than 2 hours;

[0012] Step (2): After the epoxy resin and the curing agent are fully mixed in a mass ratio of 1:1, vacuum degassing is performed at 50-60°C for no more than 20 minutes;

[0013] Step (3): After vacuum degassing, the castable is injected into the mold and cured at 90°C, 110°C, 120-130°C for 1-3 hours, 1-3 hours, and 4-6 hours, respectively.

[0014] Further, the ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, or the ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element. By assembling the positive temperature coefficient ceramic capacitor element and the negative temperature coefficient ceramic capacitor element into a positive temperature coefficient combined ceramic capacitor, the present invention realizes temperature compensation; by adjusting the quantity ratio of the positive temperature coefficient ceramic capacitor element and the negative temperature coefficient ceramic capacitor element, the capacitance ratio range of the combined ceramic capacitor is controlled to be: positive temperature coefficient capacitance: negative temperature coefficient capacitance = 4: 0.1 - 1, and the number of single capacitors required is calculated based on the capacitances of the positive and negative temperature coefficient capacitors. This combination method significantly reduces the capacitance temperature coefficient of the positive temperature coefficient combined ceramic capacitor, and the combined ceramic capacitor can be used for voltage division in high-voltage products.

[0015] Further, the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentages: BaCO3 15% - 26%, Sm2O3 10% - 25%, Nd2O3 11% - 20%, Bi2O3 12% - 18%, TiO2 30% - 36%, La2O3 0.2% - 1.0%.

[0016] Further, the ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentages: BaCO3 15% - 22%, Sm2O3 13% - 31%, Nd2O3 0% - 2%, Bi2O3 21% - 29%, TiO2 30% - 36%, La2O3 0.5% - 0.7%.

[0017] Further, the preparation method of the ceramic capacitor core material includes the following steps:

[0018] Step 1: Weigh and mix BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2, and La2O3 to obtain a premixed material;

[0019] Step 2: Mix the premixed material and water according to a mass ratio of 1: 0.7 - 1.0 and conduct the first grinding to obtain a first-stage mixed material. The duration of the first grinding is 3 - 8 hours;

[0020] Step 3: Dry the first-stage mixed material and then conduct pre-sintering to obtain a pre-sintered mixed material. The pre-sintering temperature is 1150°C - 1250°C, and the pre-sintering duration is 2 - 5 hours;

[0021] Step 4: Mix the pre-sintered mixed material and water according to a mass ratio of 1: 0.5 - 0.8, add PVA, and then conduct the second grinding to obtain a second-stage mixed material. The duration of the second grinding is 3 - 12 hours, and the mass ratio of PVA to the second-stage mixed material is 0.5% - 3%;

[0022] Step 5: Spray granulate the secondary mixture to obtain granular materials with a particle size of 100 - 300 mesh. During the spray granulation process, the inlet temperature is 280°C ± 20°C, and the outlet temperature is 100°C ± 20°C;

[0023] Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time of every 100 kg of granular materials within 30 min ± 10 min, and control the water content of the granular materials within 0.1% - 0.5% to obtain the ceramic capacitor core material.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention provides a positive temperature coefficient combined ceramic capacitor. By coaxially installing a support flange outside the high - voltage conductive rod and parallely installing ceramic capacitor elements on the support flange, the parallel combination of multiple groups of ceramic capacitor elements is realized in a mechanical structure connection manner, improving the strength and seismic performance of the combined ceramic capacitor to meet the requirement of an acceleration of 0.4g; by adjusting the quantity ratio of the positive temperature coefficient ceramic capacitor elements and the negative temperature coefficient ceramic capacitor elements in the combined ceramic capacitor, the capacitance temperature coefficient of the combined ceramic capacitor is reduced to +0.3×10 -4 / K -1 , approaching the capacitance temperature coefficient of the high - voltage gas coaxial electrode capacitor, thus matching the high - voltage gas coaxial electrode capacitor and being applicable to the tank - type capacitive voltage transformer; the combined ceramic capacitor provided by the present invention has a stable temperature coefficient within the extreme temperature range of - 35°C to +40°C, and can meet the specification requirements of a secondary winding with an error of 0.2 level. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of the combined ceramic capacitor in Embodiment 1.

[0028] Figure 2 It is a cross - sectional view of the combined ceramic capacitor in Embodiment 1.

[0029] Figure 3 It is a side view of the combined ceramic capacitor in Embodiment 1.

[0030] Figure 4 It is a cross - sectional view of the ceramic capacitor element in Embodiment 1.

[0031] Figure 5It is a top view of the ceramic capacitor element in Embodiment 1.

[0032] Figure 6 It is an overall schematic diagram of the ceramic capacitor element in Embodiment 1.

[0033] Figure 7 It is a cross-sectional view of the annular mounting plate in Embodiment 1.

[0034] Figure 8 It is a top view of the annular mounting plate in Embodiment 1.

[0035] Wherein, 1: low-voltage electrode, 2: ceramic capacitor element, 2-1: insert, 2-2: epoxy resin housing, 2-3: ceramic capacitor core, 3: fourth support flange, 4: high-voltage conductive rod, 4-1: installation and fixing end, 4-2: contact end, 5: first group of support flange installation positions. Detailed implementation manners

[0036] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment 1

[0038] A positive temperature coefficient combined ceramic capacitor, as Figures 1-8As shown in the figure, it includes a high-voltage conductive rod 4. The voltage of the high-voltage conductive rod 4 is 10 - 120 kV. The high-voltage conductive rod 4 has a cylindrical structure. One end of the high-voltage conductive rod 4 is an installation fixed end 4-1, and the installation fixed end 4-1 is physically connected to the high voltage. The other end of the high-voltage conductive rod 4 is a contact end 4-2. The contact end 4-2 is in the shape of an oblong rod, and the oblong rod shape is convenient for the support wheel and subsequent overall fixation. Along the length direction of the outer side of the high-voltage conductive rod 4, a first group of support flange installation positions 5, a second group of support flange installation positions, a third group of support flange installation positions, and a fourth group of support flange installation positions are coaxially arranged in sequence. Each group of support flange installation positions includes four mounting seats. The four mounting seats on each group of support flange installation positions are circumferentially distributed at equal intervals along the axis of the high-voltage conductive rod 4 on the outer side of the high-voltage conductive rod 4. Screw holes are opened on the mounting seats, and the screw holes on the mounting seats of each group of support flange installation positions all face the same end of the high-voltage conductive rod 4. The mounting seats on the first group of support flange installation positions 5, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions respectively coaxially install a first support flange, a second support flange, a third support flange, and a fourth support flange 3. The first support flange, the second support flange, the third support flange, and the fourth support flange 3 all include an annular mounting plate. The annular mounting plate has an annular belt structure. Four fixing parts are arranged on the inner side of the annular mounting plate. The four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting plate. The fixing parts of the first support flange, the fixing parts of the second support flange, the fixing parts of the third support flange, and the fixing parts of the fourth support flange 3 respectively correspond to the mounting seats on the first group of support flange installation positions 5, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions. Threaded holes are opened on the fixing parts, and the threaded holes penetrate through the fixing parts. The threaded holes on the fixing parts are threadedly connected to the screw holes on the mounting seats through bolts. The first support flange, the second support flange, the third support flange, and the fourth support flange 3 are respectively installed on the first group of support flange installation positions 5, the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions. Seventeen groups of capacitor installation positions are arranged on the outer side of the annular mounting plate. Multiple sets of ceramic capacitor elements 2 are assembled on each group of capacitor installation positions. The multiple sets of ceramic capacitor elements 2 are connected in parallel with each other. The ceramic capacitor element 2 is a single-layer ceramic capacitor.The ceramic capacitor element 2 includes an epoxy resin housing 2-2. Inside the epoxy resin housing 2-2, two ceramic capacitor cores 2-3 are encapsulated. Inserts 2-1 are welded to the upper and lower end faces of the two ceramic capacitor cores 2-3 respectively. The inserts on the upper end faces of the two ceramic capacitor cores 2-3 are connected to the low-voltage electrode 1 through conductive sheets. The inserts on the lower end faces of the two ceramic capacitor cores 2-3 are connected to the high-voltage conductive rod 4. The two ceramic capacitor cores 2-3 in the same ceramic capacitor element 2 are connected in parallel to achieve the required capacitance. An appropriate insulation distance is maintained between the inserts on the lower end faces of the two ceramic capacitor cores 2-3 in the same ceramic capacitor element 2. The outer surface of the ceramic capacitor core 2-3 is coated with a black glass glaze layer, and the thickness of the black glass glaze layer is 0.5 mm.

[0039] Assembly process of the combined ceramic capacitor: First, assemble and combine the first support flange, the second support flange, the third support flange, and the fourth support flange with the ceramic capacitor element, and then install them onto the high-voltage conductive rod in sequence. The outside of the ceramic capacitor element is connected to the low-voltage electrode through a conductive sheet. The overall exterior of the combined ceramic capacitor is at low voltage, and the coaxial interior is at high voltage, with a uniform electric field distribution. When installing the first support flange, the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element onto the high-voltage conductive rod, first rotate the angle, and the first support flange enters the first group of support flange installation positions through the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions in sequence. Install the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element onto the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions respectively according to the above method. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be carried out when a certain ceramic capacitor element fails. During disassembly, follow the reverse order of assembly.

[0040] The preparation method of the ceramic capacitor element includes the following steps:

[0041] Step (1): First, conduct electrical performance tests on the cured ceramic capacitor cores, and then put the ceramic capacitor cores that pass the electrical performance tests into a mold and dry them at 130°C for 4 hours; every two ceramic capacitor cores are placed in the same set of molds.

[0042] Step (2): After fully mixing epoxy resin and curing agent according to a mass ratio of 1:1, keep the temperature of the mixed epoxy resin material at 60°C and extract air bubbles in a vacuum device to obtain a casting material. The time for extracting air bubbles is 10 min.

[0043] Step (3): After vacuum degassing is completed, inject the casting material into the mold and cure it at 90°C, 110°C, and 125°C for 1 hour, 1 hour, and 5 hours respectively.

[0044] The ceramic capacitor components include positive temperature coefficient ceramic capacitor components and negative temperature coefficient ceramic capacitor components, and the quantity ratio of the positive temperature coefficient ceramic capacitor components to the negative temperature coefficient ceramic capacitor components is 64:16. Among them, the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor components includes the following components in mass percentage: 15.8% of BaCO3, 24.8% of Sm2O3, 11% of Nd2O3, 17.5% of Bi2O3, 30.6% of TiO2, and 0.3% of La2O3. The preparation method of the positive temperature coefficient ceramic capacitor core material includes the following steps:

[0045] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2 and La2O3 according to the above ratio by using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0046] Step 2: Use a ball mill to mix the premix and water according to a mass ratio of 1:1.0 and conduct the first ball milling to obtain a first-stage mixture. The duration of the first grinding is 8 hours.

[0047] Step 3: Dry the first-stage mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C, and the pre-burning duration is 3 hours.

[0048] Step 4: Mix the pre-burned mixture and water according to a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sanding to mix and grind finely. The duration of the sanding is 3 hours. After the sanding is completed, a second-stage mixture is obtained. The mass ratio of PVA to the second-stage mixture is 2.0%.

[0049] Step 5: Spray granulate the second-stage mixture to obtain fine particle materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment at 286 °C and the outlet temperature at 105 °C.

[0050] Step 6: Use an automatic mixer to mix the particle materials evenly. Control the mixing time of every 100 kg of particle materials within 30 min ± 10 min, and control the water content of the particle materials at 0.2% to obtain the positive temperature coefficient ceramic capacitor core material.

[0051] Press the positive temperature coefficient ceramic capacitor core material into a positive temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1300 °C ± 10 °C. After the firing is completed, apply electrodes, and then test the electrical properties of the positive temperature coefficient ceramic capacitor core as follows: dielectric constant 100, dielectric loss ≤ 0.0005, breakdown voltage ≥ 10 kV / mm, and capacitance temperature coefficient ≤ +30 ppm / °C.

[0052] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element comprises components in the following mass percentages: BaCO3 17.4%, Sm2O3 30.5%, Nd2O3 0%, Bi2O3 21%, TiO2 30.6%, La2O3 0.5%. The preparation method of the negative temperature coefficient ceramic capacitor core material comprises the following steps:

[0053] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2 and La2O3 according to the above ratio by using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0054] Step 2: Use a ball mill to mix the premix and water according to a mass ratio of 1:1.0 and conduct the first ball milling to obtain a first-stage mixture. The duration of the first milling is 8 hours.

[0055] Step 3: Dry the first-stage mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C, and the pre-burning duration is 3 hours.

[0056] Step 4: Mix the pre-burned mixture and water according to a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sand milling to mix and grind finely. The duration of the sand milling is 3 hours. After the sand milling is completed, a second-stage mixture is obtained. The mass ratio of PVA to the second-stage mixture is 2.0%.

[0057] Step 5: Spray granulate the second-stage mixture to obtain fine particle materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment to be 286 °C and the outlet temperature to be 105 °C.

[0058] Step 6: Use an automatic mixer to mix the particle materials evenly. Control the mixing time of every 100 kg of particle materials within 30 min ± 10 min, and control the water content of the particle materials to be 0.2% to obtain the negative temperature coefficient ceramic capacitor core material.

[0059] Press the negative temperature coefficient ceramic capacitor core material into a negative temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1290 °C ± 10 °C. After the firing is completed, apply electrodes, and then test the electrical properties of the negative temperature coefficient ceramic capacitor core as follows: dielectric constant 123 - 125, dielectric loss ≤ 0.0005, breakdown voltage ≥ 10 kV / mm, capacitance temperature coefficient ≤ -30 ppm / °C.

[0060] Example 2

[0061] A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod. The voltage of the high-voltage conductive rod is 10 - 120 kV. The high-voltage conductive rod is in a cylindrical structure. One end of the high-voltage conductive rod is an installation and fixing end, and the installation and fixing end is physically connected to the high voltage. The other end of the high-voltage conductive rod is a contact end, and the contact end is in the shape of an oblong rod, and the oblong rod shape facilitates the support wheel and subsequent overall fixation. Along the length direction on the outer side of the high-voltage conductive rod, a first group of support flange installation positions, a second group of support flange installation positions, a third group of support flange installation positions, and a fourth group of support flange installation positions are coaxially arranged in sequence. Each group of support flange installation positions includes four mounting seats. The four mounting seats on each group of support flange installation positions are circumferentially distributed at equal intervals along the axis of the high-voltage conductive rod on the outer side of the high-voltage conductive rod. A screw hole is opened on the mounting seat, and the screw holes on the mounting seats of each group of support flange installation positions all face the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions respectively coaxially install a first support flange, a second support flange, a third support flange, and a fourth support flange. The first support flange, the second support flange, the third support flange, and the fourth support flange all include an annular mounting disc. The annular mounting disc is in a ring belt structure. Four fixing parts are arranged on the inner side of the annular mounting disc. The four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting disc. The fixing parts of the first support flange, the fixing parts of the second support flange, the fixing parts of the third support flange, and the fixing parts of the fourth support flange respectively correspond to the mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions. A threaded hole is opened on the fixing part, and the threaded hole penetrates through the fixing part. The threaded hole on the fixing part and the screw hole on the mounting seat are threadedly connected by bolts. The first support flange, the second support flange, the third support flange, and the fourth support flange are respectively installed on the first group of support flange installation positions, the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions. Twenty groups of capacitor installation positions are arranged on the outer side of the annular mounting disc. Multiple sets of assembled ceramic capacitor elements are assembled on each group of capacitor installation positions. The multiple sets of ceramic capacitor elements are connected in parallel with each other. The ceramic capacitor element is a single-layer ceramic capacitor. The ceramic capacitor element includes an epoxy resin housing. Two ceramic capacitor cores are encapsulated inside the epoxy resin housing. Inserts are welded to the upper end faces and lower end faces of the two ceramic capacitor cores respectively. The inserts on the upper end faces of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet. The inserts on the lower end faces of the two ceramic capacitor cores are connected to the high-voltage conductive rod. The two ceramic capacitor cores in the same ceramic capacitor element are connected in parallel to achieve the required capacitance value. A corresponding insulation distance is maintained between the inserts on the lower end faces of the two ceramic capacitor cores in the same ceramic capacitor element. The outer surface of the ceramic capacitor core is coated with a black glass glaze layer, and the thickness of the black glass glaze layer is 0.5 mm.

[0062] The assembly process for a modular ceramic capacitor involves assembling the first, second, third, and fourth support flanges with the ceramic capacitor elements. These are then sequentially installed on the high-voltage conductive rod. The outer surfaces of the ceramic capacitor elements are connected to the low-voltage electrodes via conductive pads. The modular ceramic capacitor maintains a low voltage exterior and a high voltage interior, resulting in a uniform electric field distribution. When installing the first, second, third, and fourth support flanges, each containing ceramic capacitor elements, onto the high-voltage conductive rod, the first support flange is rotated so that it passes through the second, third, and fourth support flange mounting positions, respectively, and then into the first support flange mounting position. Following this method, the second, third, and fourth support flanges, each containing ceramic capacitor elements, are then sequentially installed onto the second, third, and fourth support flange mounting positions. Since modular ceramic capacitors consist of multiple ceramic capacitor elements, fine-tuning is possible if a ceramic capacitor element fails. Disassembly follows the reverse assembly procedure.

[0063] The preparation method of the ceramic capacitor element includes the following steps:

[0064] Step (1): First, the cured ceramic capacitor core is subjected to an electrical performance test, and then the ceramic capacitor core that has passed the electrical performance test is placed in a mold and dried at 130°C for 4 hours; every two ceramic capacitor cores are placed in the same set of molds.

[0065] Step (2): After the epoxy resin and the curing agent are fully mixed in a mass ratio of 1:1, the temperature of the mixed epoxy resin material is maintained at 60°C, and bubbles are extracted in a vacuum device to obtain a casting material. The bubble extraction time is 10 minutes.

[0066] Step (3): After vacuum degassing, the castable is injected into the mold and cured at 90°C, 110°C, and 120-130°C for 1 hour, 1 hour, and 5 hours, respectively.

[0067] The ceramic capacitor elements include positive temperature coefficient ceramic capacitor elements and negative temperature coefficient ceramic capacitor elements, and the ratio of the positive temperature coefficient ceramic capacitor elements to the negative temperature coefficient ceramic capacitor elements is 64:16. Among them, the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components by mass percentage: BaCO3 21%, Sm2O3 13.8%, Nd2O3 16.2%, Bi2O3 12.2%, TiO2 35.8%, La2O3 1%. The preparation method of the positive temperature coefficient ceramic capacitor core material includes the following steps:

[0068] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2, and La2O3 according to the above ratios using a high-precision electronic scale with a range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0069] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and conduct the first ball milling to obtain a primary mixture. The duration of the first milling is 8 hours.

[0070] Step 3: Dry the primary mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C, and the pre-burning duration is 3 hours.

[0071] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sanding to mix and grind finely. The duration of sanding is 3 hours. After sanding is completed, a secondary mixture is obtained. The mass ratio of PVA to the secondary mixture is 2.0%.

[0072] Step 5: Spray granulate the secondary mixture to obtain fine particle materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment at 286 °C and the outlet temperature at 105 °C.

[0073] Step 6: Use an automatic mixer to mix the particle materials evenly. Control the mixing time for every 100 kg of particle materials within 30 min ± 10 min, and control the water content of the particle materials at 0.2% to obtain the positive temperature coefficient ceramic capacitor core material.

[0074] Press the positive temperature coefficient ceramic capacitor core material into a positive temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1300 °C ± 10 °C. After firing is completed, apply electrodes, and then test the electrical properties of the positive temperature coefficient ceramic capacitor core as follows: dielectric constant 105, dielectric loss ≤ 0.0005, withstand voltage ≥ 10 kV / mm, capacitance temperature coefficient ≤ +60 ppm / °C.

[0075] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components by mass percentage: BaCO3 15.9%, Sm2O3 22.6%, Nd2O3 2%, Bi2O3 25.2%, TiO2 33.6%, La2O3 0.7%. The preparation method of the negative temperature coefficient ceramic capacitor core material includes the following steps:

[0076] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2 and La2O3 according to the above ratio using a high-precision electronic scale with a range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0077] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and conduct the first ball milling to obtain a primary mixture. The duration of the first milling is 8 hours.

[0078] Step 3: Dry the primary mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C and the pre-burning duration is 3 hours.

[0079] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sand milling to mix and grind finely. The duration of sand milling is 3 hours. After sand milling is completed, a secondary mixture is obtained. The mass ratio of PVA to the secondary mixture is 2.0%.

[0080] Step 5: Spray granulate the secondary mixture to obtain fine granular materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment at 286 °C and the outlet temperature at 105 °C.

[0081] Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time of every 100 kg of granular materials within 30 min ± 10 min, and control the water content of the granular materials at 0.2% to prepare the negative temperature coefficient ceramic capacitor core material.

[0082] Press the negative temperature coefficient ceramic capacitor core material into a negative temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1290 °C ± 10 °C. After firing is completed, apply electrodes, and then test the electrical properties of the negative temperature coefficient ceramic capacitor core as follows: dielectric constant 115, dielectric loss ≤ 0.0005, withstand voltage ≥ 10 kV / mm, capacitance temperature coefficient ≤ -75 ppm / °C.

[0083] Example 3

[0084] A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod with a voltage of 10 - 120 kV. The high-voltage conductive rod has a cylindrical structure. One end of the high-voltage conductive rod is an installation and fixing end, which is physically connected to the high voltage; the other end of the high-voltage conductive rod is a contact end, which is in the shape of an oblong rod, and the oblong rod shape facilitates the support wheel and subsequent overall fixation. Along the length direction of the outer side of the high-voltage conductive rod, a first group of support flange installation positions, a second group of support flange installation positions, a third group of support flange installation positions, and a fourth group of support flange installation positions are coaxially arranged in sequence. Each group of support flange installation positions includes four mounting seats, and the four mounting seats on each group of support flange installation positions are circumferentially distributed at equal intervals along the axis of the high-voltage conductive rod on the outer side of the high-voltage conductive rod. Threaded holes are opened on the mounting seats, and the threaded holes on the mounting seats of each group of support flange installation positions all face the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions are respectively coaxially installed with a first support flange, a second support flange, a third support flange, and a fourth support flange. The first support flange, the second support flange, the third support flange, and the fourth support flange all include an annular mounting plate. The annular mounting plate has an annular belt structure. Four fixing parts are arranged on the inner side of the annular mounting plate, and the four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting plate. The fixing parts of the first support flange, the fixing parts of the second support flange, the fixing parts of the third support flange, and the fixing parts of the fourth support flange respectively correspond to the mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions. Threaded holes are opened on the fixing parts, and the threaded holes penetrate through the fixing parts. The threaded holes on the fixing parts are threadedly connected to the threaded holes on the mounting seats through bolts. The first support flange, the second support flange, the third support flange, and the fourth support flange are respectively installed on the first group of support flange installation positions, the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions. Twenty groups of capacitor installation positions are arranged on the outer side of the annular mounting plate. Multiple sets of assembled ceramic capacitor elements are assembled on each group of capacitor installation positions, and the multiple sets of ceramic capacitor elements are connected in parallel with each other. The ceramic capacitor elements are single-layer ceramic capacitors. The ceramic capacitor element includes an epoxy resin housing, and two ceramic capacitor cores are encapsulated inside the epoxy resin housing. Inserts are welded to the upper and lower end faces of the two ceramic capacitor cores respectively. The inserts on the upper end faces of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet, and the inserts on the lower end faces of the two ceramic capacitor cores are connected to the high-voltage conductive rod. The two ceramic capacitor cores in the same ceramic capacitor element are connected in parallel to achieve the required capacitance; an appropriate insulation distance is maintained between the inserts on the lower end faces of the two ceramic capacitor cores in the same ceramic capacitor element; a black glass glaze layer with a thickness of 0.5 mm is coated on the outer surface of the ceramic capacitor core.

[0085] Assembly process of the combined ceramic capacitor: First, assemble and combine the first support flange, the second support flange, the third support flange, and the fourth support flange with the ceramic capacitor element, and then successively install them on the high-voltage conductive rod. The outside of the ceramic capacitor element is connected to the low-voltage electrode through a conductive sheet. The overall exterior of the combined ceramic capacitor is at low voltage, and the coaxial interior is at high voltage, with a uniform electric field distribution. When installing the first support flange, the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element on the high-voltage conductive rod, first rotate the angle, and the first support flange successively enters the first group of support flange installation positions through the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions. Install the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element on the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions in sequence according to the above method. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be carried out when a certain ceramic capacitor element fails. During disassembly, follow the reverse order of assembly.

[0086] The preparation method of the ceramic capacitor element includes the following steps:

[0087] Step (1): First, conduct electrical performance tests on the cured ceramic capacitor cores, and then put the ceramic capacitor cores that pass the electrical performance tests into the mold and dry them at 130 °C for 4 hours; every two ceramic capacitor cores are loaded into the same set of molds.

[0088] Step (2): After fully mixing epoxy resin and curing agent in a mass ratio of 1:1, keep the temperature of the mixed epoxy resin material at 60 °C and extract air bubbles in a vacuum device to obtain a casting material, and the time for extracting air bubbles is 10 min.

[0089] Step (3): After vacuum degassing is completed, inject the casting material into the mold and cure it at 90 °C, 110 °C, and 125 °C for 1 hour, 1 hour, and 5 hours respectively.

[0090] The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, and the quantity ratio of the positive temperature coefficient ceramic capacitor element to the negative temperature coefficient ceramic capacitor element is 64:16. Among them, the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO3 26%, Sm2O3 10%, Nd2O3 20%, Bi2O3 12%, TiO2 31.8%, La2O3 0.2%. The preparation method of the positive temperature coefficient ceramic capacitor core material includes the following steps:

[0091] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2, and La2O3 according to the above ratios using a high-precision electronic scale with a range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0092] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and conduct the first ball milling to obtain a first-stage mixture. The duration of the first grinding is 8 hours.

[0093] Step 3: Dry the first-stage mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C, and the pre-burning duration is 3 hours.

[0094] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sanding to mix and grind finely. The duration of sanding is 3 hours. After sanding is completed, a second-stage mixture is obtained. The mass ratio of PVA to the second-stage mixture is 2.0%.

[0095] Step 5: Spray granulate the second-stage mixture to obtain fine granular materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment at 286 °C and the outlet temperature at 105 °C.

[0096] Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time for every 100 kg of granular materials within 30 min ± 10 min, and control the water content of the granular materials at 0.2% to prepare the positive temperature coefficient ceramic capacitor core material.

[0097] Press the positive temperature coefficient ceramic capacitor core material into a positive temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1300 °C ± 10 °C. After firing is completed, apply electrodes, and then test the electrical properties of the positive temperature coefficient ceramic capacitor core as follows: dielectric constant 98, dielectric loss ≤ 0.0005, breakdown voltage ≥ 10 kV / mm, capacitance temperature coefficient ≤ +50 ppm / °C.

[0098] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentages: BaCO3 21.4%, Sm2O3 13.6%, Nd2O3 1%, Bi2O3 28.2%, TiO2 35.3%, La2O3 0.5%. The preparation method of the negative temperature coefficient ceramic capacitor core material includes the following steps:

[0099] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2, and La2O3 according to the above ratios using a high-precision electronic scale with a range of 100 kg and an accuracy of 1 g, and mix them together to obtain a premix.

[0100] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and conduct the first ball milling for 8 hours to obtain a first-stage mixture.

[0101] Step 3: Dry the first-stage mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C, and the pre-burning duration is 3 hours.

[0102] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling for 8 hours. After the second ball milling, use a sand mill for sand milling to mix and grind finely for 3 hours. After sand milling, a second-stage mixture is obtained. The mass ratio of PVA to the second-stage mixture is 2.0%.

[0103] Step 5: Spray granulate the second-stage mixture to obtain fine granular materials with a particle size of 100 - 300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment at 286 °C and the outlet temperature at 105 °C.

[0104] Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time for every 100 kg of granular materials within 30 min ± 10 min, and control the water content of the granular materials at 0.2% to obtain a negative temperature coefficient ceramic capacitor core material.

[0105] Press the negative temperature coefficient ceramic capacitor core material into a negative temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1290 °C ± 10 °C. After firing, apply electrodes, and then test the electrical properties of the negative temperature coefficient ceramic capacitor core as follows: dielectric constant 129, dielectric loss ≤ 0.0005, withstand voltage ≥ 10 kV / mm, and capacitance temperature coefficient ≤ -50 ppm / °C.

[0106] Example 4

[0107] A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod. The voltage of the high-voltage conductive rod is 10 - 120 kV. The high-voltage conductive rod has a cylindrical structure. One end of the high-voltage conductive rod is an installation and fixing end, and the installation and fixing end is physically connected to the high voltage; the other end of the high-voltage conductive rod is a contact end, and the contact end is in the shape of an oval rod, and the oval rod shape facilitates the support wheel and subsequent overall fixing. Along the length direction of the outer side of the high-voltage conductive rod, a first group of support flange installation positions, a second group of support flange installation positions, a third group of support flange installation positions, and a fourth group of support flange installation positions are coaxially arranged in sequence. Each group of support flange installation positions includes four mounting seats. The four mounting seats on each group of support flange installation positions are circumferentially distributed at equal intervals along the axis of the high-voltage conductive rod on the outer side of the high-voltage conductive rod. Threaded holes are opened on the mounting seats, and the threaded holes on the mounting seats of each group of support flange installation positions all face the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions are respectively coaxially installed with a first support flange, a second support flange, a third support flange, and a fourth support flange. The first support flange, the second support flange, the third support flange, and the fourth support flange all include an annular mounting plate. The annular mounting plate has an annular belt structure. Four fixing parts are arranged on the inner side of the annular mounting plate. The four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting plate. The fixing parts of the first support flange, the fixing parts of the second support flange, the fixing parts of the third support flange, and the fixing parts of the fourth support flange respectively correspond to the mounting seats on the first group of support flange installation positions, the mounting seats on the second group of support flange installation positions, the mounting seats on the third group of support flange installation positions, and the mounting seats on the fourth group of support flange installation positions. Threaded holes are opened on the fixing parts, and the threaded holes penetrate through the fixing parts. The threaded holes on the fixing parts are threadedly connected to the threaded holes on the mounting seats through bolts. The first support flange, the second support flange, the third support flange, and the fourth support flange are respectively installed on the first group of support flange installation positions, the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions. Twenty groups of capacitor installation positions are arranged on the outer side of the annular mounting plate. Multiple sets of assembled ceramic capacitor elements are assembled on each group of capacitor installation positions. The multiple sets of ceramic capacitor elements are connected in parallel with each other. The ceramic capacitor elements are single-layer ceramic capacitors. The ceramic capacitor element includes an epoxy resin housing. Two ceramic capacitor cores are encapsulated inside the epoxy resin housing. Inserts are welded to the upper end faces and lower end faces of the two ceramic capacitor cores respectively. The inserts on the upper end faces of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet. The inserts on the lower end faces of the two ceramic capacitor cores are connected to the high-voltage conductive rod. The two ceramic capacitor cores in the same ceramic capacitor element are connected in parallel to achieve the required capacitance; a corresponding insulation distance is maintained between the inserts on the lower end faces of the two ceramic capacitor cores in the same ceramic capacitor element; the outer surfaces of the ceramic capacitor cores are coated with a black glass glaze layer, and the thickness of the black glass glaze layer is 0.5 mm.

[0108] Assembly process of the combined ceramic capacitor: First, assemble and combine the first support flange, the second support flange, the third support flange, and the fourth support flange with the ceramic capacitor element, and then install them onto the high-voltage conductive rod in sequence. The outside of the ceramic capacitor element is connected to the low-voltage electrode through a conductive sheet. The overall exterior of the combined ceramic capacitor is at low voltage, and the coaxial interior is at high voltage, with a uniform electric field distribution. When installing the first support flange, the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element onto the high-voltage conductive rod, first rotate the angle, and the first support flange enters the first group of support flange installation positions through the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions in sequence. Install the second support flange, the third support flange, and the fourth support flange equipped with the ceramic capacitor element onto the second group of support flange installation positions, the third group of support flange installation positions, and the fourth group of support flange installation positions in sequence according to the above method. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine adjustment can be performed when a certain ceramic capacitor element fails. During disassembly, perform it in the reverse order of assembly.

[0109] The preparation method of the ceramic capacitor element includes the following steps:

[0110] Step (1): First, perform electrical performance testing on the cured ceramic capacitor core, and then put the ceramic capacitor core with qualified electrical performance into a mold and dry it at 130 °C for 2 to 5 hours; every two ceramic capacitor cores are loaded into the same set of molds.

[0111] Step (2): After fully mixing epoxy resin and curing agent in a mass ratio of 1:1, keep the temperature of the mixed epoxy resin material at 60 °C, and extract air bubbles in a vacuum device to obtain a casting material. The time for extracting air bubbles is 15 min.

[0112] Step (3): After vacuum degassing is completed, inject the casting material into the mold and cure it at 90 °C, 110 °C, and 120 - 130 °C for 1 hour, 1 hour, and 5 hours respectively.

[0113] The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element. The ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO3 16.6%, Sm2O3 20.2%, Nd2O3 19.3%, Bi2O3 12%, TiO2 30.9%, La2O3 1%. The preparation method of the positive temperature coefficient ceramic capacitor core material includes the following steps:

[0114] Step 1: Weigh BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2, and La2O3 according to the above ratio using a high-precision electronic scale with a range of 100 kg and an accuracy of 1 g and mix them together to obtain a premix.

[0115] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and conduct the first ball milling to obtain a first-stage mixture. The duration of the first grinding is 8 hours.

[0116] Step 3: Dry the first-stage mixture and then pre-burn it using an electric tunnel furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200 °C and the duration of pre-burning is 3 hours.

[0117] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 type PVA, and then use a ball mill for the second ball milling. The duration of the second ball milling is 8 hours. After the second ball milling is completed, use a sand mill for sand grinding to mix and grind finely. The duration of sand grinding is 3 hours. After sand grinding is completed, a second-stage mixture is obtained. The mass ratio of PVA to the second-stage mixture is 2.0%.

[0118] Step 5: Spray granulate the second-stage mixture to obtain fine granular materials with a particle size of 100-300 mesh. During the spray granulation process, control the inlet temperature of the spray granulation equipment to be 286 °C and the outlet temperature to be 105 °C.

[0119] Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time of every 100 kg of granular materials within 30 min ± 10 min and control the water content of the granular materials to be 0.2% to obtain the positive temperature coefficient ceramic capacitor core material.

[0120] Press the positive temperature coefficient ceramic capacitor core material into a positive temperature coefficient ceramic capacitor core, and then conduct firing. The firing temperature is 1300 °C ± 10 °C. After firing is completed, apply electrodes, and then test the electrical properties of the positive temperature coefficient ceramic capacitor core as follows: dielectric constant 108, dielectric loss ≤ 0.0005, withstand voltage ≥ 10 kV / mm, capacitance temperature coefficient ≤ +50 ppm / °C.

[0121] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope covered by the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A positive temperature coefficient combined ceramic capacitor, comprising a high-voltage conductive rod, characterized in that, The high-voltage conductive rod is a cylindrical structure. A support flange is coaxially mounted on the outside of the high-voltage conductive rod. Multiple groups of ceramic capacitor elements are assembled on the support flange. The multiple groups of ceramic capacitor elements are connected in parallel with each other, and the overall temperature coefficient of the multiple groups of ceramic capacitor elements is positive. The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, or the ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element; The ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO315%-26%, Sm2O3 10%-25%, Nd2O3 11%-20%, Bi2O3 12%-18%, TiO2 30%-36%, La2O3 0.2%-1.0%; The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO315%-22%, Sm2O3 13%-31%, Nd2O3 0%-2%, Bi2O3 21%-29%, TiO2 30%-36%, La2O3 0.5%-0.7%; The ceramic capacitor element includes an epoxy resin shell, which contains two ceramic capacitor cores. The upper end surface of the two ceramic capacitor cores is connected to the low-voltage electrode, and the lower end surface of the two ceramic capacitor cores is connected to the high-voltage conductive rod. The outer side of the epoxy resin shell is coated with a black glass glaze layer, and the thickness of the black glass glaze layer is 0.2-0.5mm.

2. The combined ceramic capacitor according to claim 1, wherein Four groups of support flange mounting positions are coaxially arranged on the outside of the high-voltage conductive rod along the length direction. Each group of support flange mounting positions includes four mounting seats, and the four mounting seats are evenly spaced and circumferentially distributed on the outside of the high-voltage conductive rod.

3. The combined ceramic capacitor according to claim 2, wherein, Screw holes are provided on the mounting base.

4. The combined ceramic capacitor according to claim 3, characterized in that, The supporting flange includes an annular mounting plate, the inner side of which is provided with four fixing parts, which are threadedly connected to the mounting seat, and the outer side of the annular mounting plate is provided with a capacitor mounting position, on which a ceramic capacitor element is mounted.

5. The combined ceramic capacitor according to claim 1, characterized in that, The preparation method of the ceramic capacitor element includes the following steps: Step (1): Place the ceramic capacitor core into a mold and dry it at 120-140°C for more than 2 hours; Step (2): After the epoxy resin and the curing agent are fully mixed in a mass ratio of 1:1, vacuum degassing is performed at 50-60°C to obtain a casting material. The vacuum degassing time shall not exceed 20 minutes; Step (3): After vacuum degassing, the castable is injected into the mold and cured at 90°C, 110°C, 120-130°C for 1-3 hours, 1-3 hours, and 4-6 hours, respectively.

6. The combined ceramic capacitor according to claim 1, wherein, The preparation method of ceramic capacitor core material includes the following steps: Step 1: BaCO3, Sm2O3, Nd2O3, Bi2O3, TiO2 and La2O3 are weighed and mixed to obtain a premix; Step 2: Mix the premix and water in a mass ratio of 1:0.7-1.0 and grind for the first time to obtain a primary mixture. The first grinding time is 3-8 hours; Step 3: Dry the primary mixture and then carry out pre-sintering to obtain a pre-sintered mixture. The pre-sintering temperature is 1150°C - 1250°C, and the pre-sintering duration is 2 - 5 hours; Step 4: Mix the pre-sintered mixture and water in a mass ratio of 1:0.5 - 0.8, then add PVA and carry out secondary grinding to obtain a secondary mixture. The secondary grinding duration is 3 - 12 hours, and the mass ratio of PVA to the secondary mixture is 0.5% - 3%; Step 5: Carry out spray granulation on the secondary mixture to obtain granular materials with a particle size of 100 - 300 mesh. During the spray granulation process, the inlet temperature is 280°C ± 20°C, and the outlet temperature is 100°C ± 20°C; Step 6: Use an automatic mixer to mix the granular materials evenly. Control the mixing time of every 100 kg of granular materials within 30 min ± 10 min, and control the water content of the granular materials within 0.1% - 0.5% to obtain the ceramic capacitor core material.

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