Positive temperature coefficient combined ceramic capacitor

Abstract

The invention relates to the technical field of ceramic capacitors, in particular to a positive temperature coefficient combined ceramic capacitor which comprises a high-voltage conducting rod, the high-voltage conducting rod is of a cylindrical structure, a supporting flange is coaxially installed on the outer side of the high-voltage conducting rod, and ceramic capacitor elements are installed on the supporting flange in parallel. The ceramic capacitor elements are installed on the supporting flange on the outer side of the high-voltage conducting rod in parallel, the strength of the combined ceramic capacitor is improved, and meanwhile the overall temperature coefficient of the combined ceramic capacitor is remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic capacitors, and in particular to a combined 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 conductive plates and an insulating medium sandwiched between the conductive plates. When the two conductive plates of the capacitor are connected to a power source, positive charges and negative charges accumulate on the two conductive plates respectively, and electrical energy is stored by forming an electric field; when the two conductive plates of the capacitor are disconnected from the power source, the charges on the two conductive plates are released through an external circuit, converting electrical energy 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 negative temperature coefficients have the characteristics of small size, low cost, and high energy density, but poor temperature stability, 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 dividers for high-voltage capacitive voltage transformers. However, the absolute value of the temperature coefficient of film capacitors is large, the capacitance value decreases significantly when the temperature rises, the voltage divider ratio is greatly affected by temperature, and there is a large amount of residual inductance, which hinders the transmission of high-frequency overvoltage and easily causes local overvoltage breakdown. When film capacitors are used in gas capacitor transformer products, the film capacitors are matched with high-voltage coaxial electrode capacitors, which results in temperature coefficient mismatch, poor error accuracy, and failure to meet accuracy specifications under extreme temperatures and specified loads. In addition, the coaxial winding structure has low mechanical strength and poses a risk of slippage. Summary of the invention

[0003] In view of the problem of temperature coefficient mismatch when film capacitors are used in conjunction with high-voltage coaxial electrode capacitors, the present invention provides a combined ceramic capacitor with a positive temperature coefficient. By installing ceramic capacitor elements in parallel on a supporting flange on the outside of a high-voltage conductive rod, the strength of the combined ceramic capacitor is improved while the overall temperature coefficient of the combined ceramic capacitor is significantly reduced.

[0004] The technical solution of the present invention is as follows: A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod, which is a cylindrical structure, a support flange is coaxially mounted on the outer side of the high-voltage conductive rod, and multiple groups of ceramic capacitor elements are assembled on the support flange. The multiple groups of ceramic capacitor elements are connected in parallel, and the overall temperature coefficient of the multiple groups of ceramic capacitor elements is positive. The voltage of the high-voltage conductive rod is 0-120kV.

[0005] Furthermore, four groups of support flange mounting positions are coaxially arranged along the length direction on the outer side of the high-voltage conductive rod, 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.

[0006] Furthermore, screw holes are provided on the mounting seats, and the screw holes on each mounting seat are all facing the same end of the high-voltage conductive rod.

[0007] Furthermore, the supporting flange includes an annular mounting disk, which is a ring-shaped structure. Four fixing parts are arranged on the inner side of the annular mounting disk. The four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting disk. 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 disk. Ceramic capacitor elements are installed on each group of capacitor mounting positions. The ceramic capacitor elements are single-layer ceramic capacitors.

[0008] 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 epoxy resin encapsulation technology to control the capacitance deviation of the combined ceramic capacitor within the range of ±2%. The upper end face of the ceramic capacitor core 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.

[0009] Furthermore, the preparation method of the ceramic capacitor element comprises 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., and the vacuum degassing time does not exceed 20 minutes; Step (3): After vacuum degassing, the casting material 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.

[0010] Furthermore, 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 present invention realizes temperature compensation by assembling a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element into a positive temperature coefficient combined ceramic capacitor; by adjusting the ratio of the number of positive temperature coefficient ceramic capacitor elements and negative temperature coefficient ceramic capacitor elements, the capacitance ratio range of the combined ceramic capacitor is controlled within: positive temperature coefficient capacitance: negative temperature coefficient capacitance = 4: 0.1-1, and the number of single capacitors required is calculated based on the capacitance 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 of high voltage products.

[0011] Furthermore, the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in percentage by mass: BaCO 3 15%-26%, Sm 2 O 3 10%-25%, Nd 2 O 3 11%-20%,Bi 2 O 3 12%-18%, TiO 2 30%-36%, La 2 O 3 0.2%-1.0%.

[0012] Furthermore, the ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in percentage by mass: BaCO 3 15%-22%, Sm 2 O 3 13%-31%, Nd 2 O 3 0%-2%,Bi 2 O 3 21%-29%, TiO 2 30%-36%, La 2 O 3 0.5%-0.7%.

[0013] Furthermore, the preparation method of the ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2O 3 After weighing, mix 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: drying the primary mixture and pre-burning it to obtain a pre-burned mixture, the pre-burning temperature is 1150°C-1250°C, and the pre-burning time is 2-5 hours; Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.5-0.8, add PVA, and then grind for the second time to obtain a secondary mixture. The second grinding time is 3-12 hours, and the mass ratio of PVA to the mass of the secondary mixture is 0.5%-3%; Step 5: spray granulate the secondary mixture to obtain a granular material 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 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.1%-0.5%, to obtain ceramic capacitor core materials.

[0014] The beneficial effects of the present invention are: The present invention provides a combined ceramic capacitor with a positive temperature coefficient. A supporting flange is coaxially installed on the outer side of a high-voltage conductive rod, and ceramic capacitor elements are installed in parallel on the supporting flange. A parallel combination of multiple groups of ceramic capacitor elements is achieved by mechanical structure connection, thereby improving the strength and seismic resistance of the combined ceramic capacitor and meeting the acceleration requirement 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 , close to the capacitance temperature coefficient of the high-pressure gas coaxial electrode capacitor, thereby matching the high-pressure gas coaxial electrode capacitor and can be used in tank-type capacitor mutual inductors; 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 achieve the secondary winding meeting the specification requirement of 0.2 level error. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 Schematic diagram of the structure of the combined ceramic capacitor in Example 1.

[0017] Figure 2 is a cross-sectional view of the combined ceramic capacitor in Example 1.

[0018] Figure 3 3 is a side view of the combined ceramic capacitor in Example 1.

[0019] Figure 4 is a cross-sectional view of the ceramic capacitor element in Example 1.

[0020] Figure 5 1 is a top view of the ceramic capacitor element in Example 1.

[0021] Figure 6 Schematic diagram of the ceramic capacitor element in Example 1.

[0022] Figure 7 2 is a cross-sectional view of the annular mounting plate in Example 1.

[0023] Figure 8 3. It is a top view of the annular mounting plate in Example 1.

[0024] Among them, 1: low voltage electrode, 2: ceramic capacitor element, 2-1: insert, 2-2: epoxy resin shell, 2-3: ceramic capacitor core, 3: fourth support flange, 4: high voltage conductive rod, 4-1: installation fixed end, 4-2: contact end, 5: first group of support flange installation position. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] Example 1 A positive temperature coefficient combination ceramic capacitor, such as Figure 1-Figure 8As shown, it includes a high-voltage conductive rod 4, the voltage of the high-voltage conductive rod 4 is 10-120kV, the high-voltage conductive rod 4 is a cylindrical structure, one end of the high-voltage conductive rod 4 is a mounting and fixing end 4-1, and the mounting and fixing 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, and the contact end 4-2 is in the shape of an elongated round rod, and the shape of the elongated round rod is convenient for supporting wheels and subsequent overall fixation. The outer side of the high-voltage conductive rod 4 is coaxially arranged with a first group of supporting flange mounting positions 5, a second group of supporting flange mounting positions, a third group of supporting flange mounting positions, and a fourth group of supporting flange mounting positions in sequence along the length direction, each group of supporting flange mounting positions includes four mounting seats, and the four mounting seats on each group of supporting flange mounting positions are circumferentially distributed on the outer side of the high-voltage conductive rod 4 at equal intervals along the axis of the high-voltage conductive rod 4, and screw holes are provided on the mounting seats, and the screw holes on the mounting seats of each group of supporting flange mounting positions are all facing the same end of the high-voltage conductive rod 4. The mounting seats on the first group of support flange mounting positions 5, the mounting seats on the second group of support flange mounting positions, the mounting seats on the third group of support flange mounting positions and the mounting seats on the fourth group of support flange mounting positions are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the 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 disk, the annular mounting disk is an annular belt structure, four fixing parts are arranged on the inner side of the annular mounting disk, and the four fixing parts are circumferentially distributed at equal intervals along the axis of the annular mounting disk, the fixing part of the first support flange, the fixing part of the second support flange, the third support flange The fixing part of the flange and the fixing part of the fourth support flange 3 respectively correspond to the mounting seat on the first group of support flange mounting positions 5, the mounting seat on the second group of support flange mounting positions, the mounting seat on the third group of support flange mounting positions and the mounting seat on the fourth group of support flange mounting positions, a threaded hole is provided on the fixing part, the threaded hole passes through the fixing part, the threaded hole on the fixing part is connected with the screw hole on the mounting seat by bolt threads, and 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 mounting positions 5, the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions. Seventeen groups of capacitor mounting positions are arranged on the outer side of the annular mounting plate, and multiple groups of ceramic capacitor elements 2 are assembled on each group of capacitor mounting positions, and multiple groups of ceramic capacitor elements 2 are connected in parallel with each other, and the ceramic capacitor elements 2 are single-layer ceramic capacitors.The ceramic capacitor element 2 includes an epoxy resin shell 2-2, and two ceramic capacitor cores 2-3 are encapsulated inside the epoxy resin shell 2-2. The upper end faces and lower end faces of the two ceramic capacitor cores 2-3 are respectively welded with inserts 2-1. The upper end face inserts of the two ceramic capacitor cores 2-3 are connected to the low-voltage electrode 1 through a conductive sheet, and the lower end face inserts 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; the corresponding insulation distance is maintained between the lower end face inserts 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.

[0027] The assembly process of the combined ceramic capacitor: first, assemble 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 on the high-voltage conductive rod in sequence. The outer side of the ceramic capacitor element is connected to the low-voltage electrode through the conductive sheet. The overall outer side of the combined ceramic capacitor is low voltage, the coaxial inner side is high voltage, and the electric field is evenly distributed. 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 first support flange through the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions to enter the first group of support flange mounting positions. According to the above method, the second support flange, the third support flange and the fourth support flange equipped with the ceramic capacitor element are installed on the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions in sequence. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be performed when a ceramic capacitor element fails. When disassembling, proceed in the reverse order of assembly.

[0028] The method for preparing a ceramic capacitor element comprises the following steps: Step (1): firstly, the electrical performance of the cured ceramic capacitor core is tested, 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.

[0029] 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.

[0030] Step (3): After vacuum degassing, the casting material is injected into the mold and cured at 90°C, 110°C, and 125°C for 1 hour, 1 hour, and 5 hours, respectively.

[0031] The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, and the 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: BaCO 3 15.8%, Sm 2 O 3 24.8%, Nd 2 O 3 11%,Bi 2 O 3 17.5%, TiO 2 30.6%, La 2 O 3 0.3%. The preparation method of the positive temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0032] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0033] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0034] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0035] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0036] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the positive temperature coefficient ceramic capacitor core material.

[0037] The positive temperature coefficient ceramic capacitor core material is pressed into a positive temperature coefficient ceramic capacitor core, and then fired at a temperature of 1300°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the positive temperature coefficient ceramic capacitor core are tested: dielectric constant 100, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ +30ppm / °C.

[0038] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO 3 17.4%, Sm 2 O 3 30.5%,Nd 2 O 3 0%,Bi 2 O 3 21%, TiO 2 30.6%, La 2 O 3 0.5%. The preparation method of the negative temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0039] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0040] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0041] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0042] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0043] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the negative temperature coefficient ceramic capacitor core material.

[0044] The negative temperature coefficient ceramic capacitor core material is pressed into a negative temperature coefficient ceramic capacitor core, and then fired at a temperature of 1290°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the negative temperature coefficient ceramic capacitor core are tested: dielectric constant 123-125, dielectric loss ≤0.0005, withstand voltage ≥10kV / mm, capacitance temperature coefficient ≤-30ppm / °C.

[0045] Example 2 A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod, the voltage of the high-voltage conductive rod is 10-120kV, the high-voltage conductive rod is a cylindrical structure, one end of the high-voltage conductive rod is a mounting and fixing end, and the mounting 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 elongated round rod, and the shape of the elongated round rod is convenient for supporting wheels and subsequent overall fixation. The outer side of the high-voltage conductive rod is coaxially arranged with a first group of supporting flange mounting positions, a second group of supporting flange mounting positions, a third group of supporting flange mounting positions, and a fourth group of supporting flange mounting positions in sequence along the length direction. Each group of supporting flange mounting positions includes four mounting seats, and the four mounting seats on each group of supporting flange mounting positions 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, and screw holes are provided on the mounting seats, and the screw holes on the mounting seats of each group of supporting flange mounting positions are all facing the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange mounting positions, the mounting seats on the second group of support flange mounting positions, the mounting seats on the third group of support flange mounting positions and the mounting seats on the fourth group of support flange mounting positions are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the 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 is 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 second support flange, the third support flange and the fourth support flange are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the fourth support flange The fixing part of the flange and the fixing part of the fourth supporting flange respectively correspond to the mounting seat on the first group of supporting flange mounting positions, the mounting seat on the second group of supporting flange mounting positions, the mounting seat on the third group of supporting flange mounting positions and the mounting seat on the fourth group of supporting flange mounting positions, a threaded hole is provided on the fixing part, the threaded hole passes through the fixing part, the threaded hole on the fixing part is connected with the screw hole on the mounting seat by bolt threads, and the first supporting flange, the second supporting flange, the third supporting flange and the fourth supporting flange are respectively installed on the first group of supporting flange mounting positions, the second group of supporting flange mounting positions, the third group of supporting flange mounting positions and the fourth group of supporting flange mounting positions. Twenty groups of capacitor mounting positions are arranged on the outer side of the annular mounting plate, and multiple groups of ceramic capacitor elements are assembled on each group of capacitor mounting positions, and the multiple groups of ceramic capacitor elements are connected in parallel with each other, and the ceramic capacitor elements are single-layer ceramic capacitors. The ceramic capacitor element includes an epoxy resin shell, in which two ceramic capacitor cores are encapsulated, and the upper end faces and lower end faces of the two ceramic capacitor cores are respectively welded with inserts, the upper end face inserts of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet, and the lower end face inserts 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; the lower end face inserts of the two ceramic capacitor cores in the same ceramic capacitor element maintain a corresponding insulation distance between them; 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.

[0046] The assembly process of the combined ceramic capacitor: first, assemble 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 on the high-voltage conductive rod in sequence. The outer side of the ceramic capacitor element is connected to the low-voltage electrode through the conductive sheet. The overall outer side of the combined ceramic capacitor is low voltage, the coaxial inner side is high voltage, and the electric field is evenly distributed. 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 first support flange through the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions to enter the first group of support flange mounting positions. According to the above method, the second support flange, the third support flange and the fourth support flange equipped with the ceramic capacitor element are installed on the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions in sequence. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be performed when a ceramic capacitor element fails. When disassembling, proceed in the reverse order of assembly.

[0047] The method for preparing a ceramic capacitor element comprises the following steps: Step (1): firstly, the electrical performance of the cured ceramic capacitor core is tested, 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.

[0048] 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.

[0049] Step (3): After vacuum degassing, the casting material 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.

[0050] The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, and the 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: BaCO 3 21%, Sm 2 O 3 13.8%,Nd 2 O 3 16.2%,Bi 2 O 3 12.2%, TiO 2 35.8%, La 2 O3 1%. The preparation method of the positive temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0051] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0052] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0053] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0054] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0055] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the positive temperature coefficient ceramic capacitor core material.

[0056] The positive temperature coefficient ceramic capacitor core material is pressed into a positive temperature coefficient ceramic capacitor core, and then fired at a temperature of 1300°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the positive temperature coefficient ceramic capacitor core are tested: dielectric constant 105, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ +60ppm / °C.

[0057] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO 3 15.9%, Sm 2 O 3 22.6%, Nd 2 O 3 2%,Bi 2 O 3 25.2%, TiO 2 33.6%, La 2 O 3 0.7%. The preparation method of the negative temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0058] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0059] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0060] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0061] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0062] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the negative temperature coefficient ceramic capacitor core material.

[0063] The negative temperature coefficient ceramic capacitor core material is pressed into a negative temperature coefficient ceramic capacitor core, and then fired at a temperature of 1290°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the negative temperature coefficient ceramic capacitor core are tested: dielectric constant 115, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ -75ppm / °C.

[0064] Example 3 A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod, the voltage of the high-voltage conductive rod is 10-120kV, the high-voltage conductive rod is a cylindrical structure, one end of the high-voltage conductive rod is a mounting and fixing end, and the mounting 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 elongated round rod, and the shape of the elongated round rod is convenient for supporting wheels and subsequent overall fixation. The outer side of the high-voltage conductive rod is coaxially arranged with a first group of supporting flange mounting positions, a second group of supporting flange mounting positions, a third group of supporting flange mounting positions, and a fourth group of supporting flange mounting positions in sequence along the length direction. Each group of supporting flange mounting positions includes four mounting seats, and the four mounting seats on each group of supporting flange mounting positions 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, and screw holes are provided on the mounting seats, and the screw holes on the mounting seats of each group of supporting flange mounting positions are all facing the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange mounting positions, the mounting seats on the second group of support flange mounting positions, the mounting seats on the third group of support flange mounting positions and the mounting seats on the fourth group of support flange mounting positions are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the 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 is 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 second support flange, the third support flange and the fourth support flange are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the fourth support flange The fixing part of the flange and the fixing part of the fourth supporting flange respectively correspond to the mounting seat on the first group of supporting flange mounting positions, the mounting seat on the second group of supporting flange mounting positions, the mounting seat on the third group of supporting flange mounting positions and the mounting seat on the fourth group of supporting flange mounting positions, a threaded hole is provided on the fixing part, the threaded hole passes through the fixing part, the threaded hole on the fixing part is connected with the screw hole on the mounting seat by bolt threads, and the first supporting flange, the second supporting flange, the third supporting flange and the fourth supporting flange are respectively installed on the first group of supporting flange mounting positions, the second group of supporting flange mounting positions, the third group of supporting flange mounting positions and the fourth group of supporting flange mounting positions. Twenty groups of capacitor mounting positions are arranged on the outer side of the annular mounting plate, and multiple groups of ceramic capacitor elements are assembled on each group of capacitor mounting positions, and the multiple groups of ceramic capacitor elements are connected in parallel with each other, and the ceramic capacitor elements are single-layer ceramic capacitors. The ceramic capacitor element includes an epoxy resin shell, in which two ceramic capacitor cores are encapsulated, and the upper end faces and lower end faces of the two ceramic capacitor cores are respectively welded with inserts, the upper end face inserts of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet, and the lower end face inserts 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; the lower end face inserts of the two ceramic capacitor cores in the same ceramic capacitor element maintain a corresponding insulation distance between them; 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.

[0065] The assembly process of the combined ceramic capacitor: first, assemble 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 on the high-voltage conductive rod in sequence. The outer side of the ceramic capacitor element is connected to the low-voltage electrode through the conductive sheet. The overall outer side of the combined ceramic capacitor is low voltage, the coaxial inner side is high voltage, and the electric field is evenly distributed. 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 first support flange through the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions to enter the first group of support flange mounting positions. According to the above method, the second support flange, the third support flange and the fourth support flange equipped with the ceramic capacitor element are installed on the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions in sequence. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be performed when a ceramic capacitor element fails. When disassembling, proceed in the reverse order of assembly.

[0066] The method for preparing a ceramic capacitor element comprises the following steps: Step (1): firstly, the electrical performance of the cured ceramic capacitor core is tested, 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.

[0067] 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.

[0068] Step (3): After vacuum degassing, the casting material is injected into the mold and cured at 90°C, 110°C, and 125°C for 1 hour, 1 hour, and 5 hours, respectively.

[0069] The ceramic capacitor element includes a positive temperature coefficient ceramic capacitor element and a negative temperature coefficient ceramic capacitor element, and the 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: BaCO 3 26%, Sm 2 O 3 10%, Nd 2 O 3 20%,Bi 2 O 3 12%, TiO 2 31.8%, La 2 O 30.2%. The preparation method of the positive temperature coefficient ceramic capacitor core material includes the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0070] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0071] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0072] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0073] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0074] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the positive temperature coefficient ceramic capacitor core material.

[0075] The positive temperature coefficient ceramic capacitor core material is pressed into a positive temperature coefficient ceramic capacitor core, and then fired at a temperature of 1300°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the positive temperature coefficient ceramic capacitor core are tested: dielectric constant 98, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ +50ppm / °C.

[0076] The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO 3 21.4%, Sm 2 O 3 13.6%, Nd 2 O 3 1%,Bi 2 O 3 28.2%, TiO 2 35.3%, La 2 O 3 0.5%. The preparation method of the negative temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g 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 perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0078] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

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

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

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

[0082] The negative temperature coefficient ceramic capacitor core material is pressed into a negative temperature coefficient ceramic capacitor core, and then fired at a temperature of 1290°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the negative temperature coefficient ceramic capacitor core are tested: dielectric constant 129, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ -50ppm / °C.

[0083] Example 4 A positive temperature coefficient combined ceramic capacitor includes a high-voltage conductive rod, the voltage of the high-voltage conductive rod is 10-120kV, the high-voltage conductive rod is a cylindrical structure, one end of the high-voltage conductive rod is a mounting and fixing end, and the mounting 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 elongated round rod, and the shape of the elongated round rod is convenient for supporting wheels and subsequent overall fixation. The outer side of the high-voltage conductive rod is coaxially arranged with a first group of supporting flange mounting positions, a second group of supporting flange mounting positions, a third group of supporting flange mounting positions, and a fourth group of supporting flange mounting positions in sequence along the length direction. Each group of supporting flange mounting positions includes four mounting seats, and the four mounting seats on each group of supporting flange mounting positions 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, and screw holes are provided on the mounting seats, and the screw holes on the mounting seats of each group of supporting flange mounting positions are all facing the same end of the high-voltage conductive rod. The mounting seats on the first group of support flange mounting positions, the mounting seats on the second group of support flange mounting positions, the mounting seats on the third group of support flange mounting positions and the mounting seats on the fourth group of support flange mounting positions are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the 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 is 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 second support flange, the third support flange and the fourth support flange are respectively coaxially mounted with the first support flange, the second support flange, the third support flange and the fourth support flange The fixing part of the flange and the fixing part of the fourth supporting flange respectively correspond to the mounting seat on the first group of supporting flange mounting positions, the mounting seat on the second group of supporting flange mounting positions, the mounting seat on the third group of supporting flange mounting positions and the mounting seat on the fourth group of supporting flange mounting positions, a threaded hole is provided on the fixing part, the threaded hole passes through the fixing part, the threaded hole on the fixing part is connected with the screw hole on the mounting seat by bolt threads, and the first supporting flange, the second supporting flange, the third supporting flange and the fourth supporting flange are respectively installed on the first group of supporting flange mounting positions, the second group of supporting flange mounting positions, the third group of supporting flange mounting positions and the fourth group of supporting flange mounting positions. Twenty groups of capacitor mounting positions are arranged on the outer side of the annular mounting plate, and multiple groups of ceramic capacitor elements are assembled on each group of capacitor mounting positions, and the multiple groups of ceramic capacitor elements are connected in parallel with each other, and the ceramic capacitor elements are single-layer ceramic capacitors. The ceramic capacitor element includes an epoxy resin shell, in which two ceramic capacitor cores are encapsulated, and the upper end faces and lower end faces of the two ceramic capacitor cores are respectively welded with inserts, the upper end face inserts of the two ceramic capacitor cores are connected to the low-voltage electrode through a conductive sheet, and the lower end face inserts 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; the lower end face inserts of the two ceramic capacitor cores in the same ceramic capacitor element maintain a corresponding insulation distance between them; 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.

[0084] The assembly process of the combined ceramic capacitor: first, assemble 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 on the high-voltage conductive rod in sequence. The outer side of the ceramic capacitor element is connected to the low-voltage electrode through the conductive sheet. The overall outer side of the combined ceramic capacitor is low voltage, the coaxial inner side is high voltage, and the electric field is evenly distributed. 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 first support flange through the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions to enter the first group of support flange mounting positions. According to the above method, the second support flange, the third support flange and the fourth support flange equipped with the ceramic capacitor element are installed on the second group of support flange mounting positions, the third group of support flange mounting positions and the fourth group of support flange mounting positions in sequence. Since the combined ceramic capacitor is composed of multiple ceramic capacitor elements, fine-tuning can be performed when a ceramic capacitor element fails. When disassembling, proceed in the reverse order of assembly.

[0085] The method for preparing a ceramic capacitor element comprises the following steps: Step (1): firstly, the electrical performance of the cured ceramic capacitor core is tested, and then the ceramic capacitor core that has passed the electrical performance test is placed in a mold and dried at 130° C. for 2 to 5 hours; every two ceramic capacitor cores are placed in the same set of molds.

[0086] 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 time for extracting bubbles is 15 minutes.

[0087] Step (3): After vacuum degassing, the casting material 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.

[0088] Ceramic capacitor elements include positive temperature coefficient ceramic capacitor elements, and the ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO 3 16.6%, Sm 2 O 3 20.2%, Nd 2 O 3 19.3%,Bi 2 O 3 12%, TiO 2 30.9%, La 2 O 3 1%. The preparation method of the positive temperature coefficient ceramic capacitor core material comprises the following steps: Step 1: BaCO 3 、Sm 2 O 3 、Nd 2 O 3 、Bi 2 O 3 、TiO 2 and La 2 O 3 According to the above ratio, the mixture is weighed and mixed using a high-precision electronic scale with a measuring range of 100 kg and an accuracy of 1 g to obtain a premix.

[0089] Step 2: Use a ball mill to mix the premix and water in a mass ratio of 1:1.0 and perform the first ball milling to obtain a primary mixture. The first grinding time is 8 hours.

[0090] Step 3: After drying the primary mixture, pre-burn it in an electric furnace to obtain a pre-burned mixture. The pre-burning temperature is 1200° C. and the pre-burning time is 3 hours.

[0091] Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.6, add 17-88 PVA, and then use a ball mill for a second ball milling. The second ball milling time is 8 hours. After the second ball milling is completed, use a sand mill for sand milling, mix and grind, the sand milling time is 3 hours, and after sand milling, a secondary mixture is obtained. The ratio of the mass of PVA to the mass of the secondary mixture is 2.0%.

[0092] Step 5: spray granulate the secondary mixture to obtain fine granular material with a particle size of 100-300 mesh. During the spray granulation process, the inlet temperature of the spray granulation equipment is controlled to be 286°C and the outlet temperature is controlled to be 105°C.

[0093] Step 6: Use an automatic mixer to mix the granular materials evenly, control the mixing time of every 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.2%, so as to obtain the positive temperature coefficient ceramic capacitor core material.

[0094] The positive temperature coefficient ceramic capacitor core material is pressed into a positive temperature coefficient ceramic capacitor core, and then fired at a temperature of 1300°C ± 10°C. After firing, the electrodes are painted, and then the electrical properties of the positive temperature coefficient ceramic capacitor core are tested: dielectric constant 108, dielectric loss ≤ 0.0005, withstand voltage ≥ 10kV / mm, capacitance temperature coefficient ≤ +50ppm / °C.

[0095] Although the present invention has been described in detail with reference 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, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection 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 supporting flange is coaxially installed on the outer side of the high-voltage conductive rod. Multiple groups of ceramic capacitor elements are assembled on the supporting 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.

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

3. The composite ceramic capacitor according to claim 2, wherein: The mounting base is provided with screw holes.

4. The composite ceramic capacitor according to claim 3, wherein: The supporting flange comprises an annular mounting plate, four fixing parts are arranged on the inner side of the annular mounting plate, the fixing parts are threadedly connected with the mounting seat, a capacitor mounting position is arranged on the outer side of the annular mounting plate, and a ceramic capacitor element is installed on the capacitor mounting position.

5. The composite ceramic capacitor according to claim 1, wherein: The ceramic capacitor element includes an epoxy resin shell, in which two ceramic capacitor cores are encapsulated, the upper end surfaces of the two ceramic capacitor cores are connected to the low-voltage electrode, and the lower end surfaces of the two ceramic capacitor cores are 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.

6. The composite ceramic capacitor according to claim 5, wherein: The method for preparing a ceramic capacitor element comprises 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, and the vacuum degassing time does not exceed 20 minutes; Step (3): After vacuum degassing, the casting material 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.

7. The composite ceramic capacitor according to claim 5, characterized in that 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.

8. The combined ceramic capacitor according to claim 7, wherein: The ceramic capacitor core material of the positive temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO3 15%-26%, Sm2O3 10%-25%, Nd2O3 11%-20%, Bi2O3 12%-18%, TiO2 30%-36%, and La2O3 0.2%-1.0%.

9. The combined ceramic capacitor according to claim 7, wherein: The ceramic capacitor core material of the negative temperature coefficient ceramic capacitor element includes the following components in mass percentage: BaCO3 15%-22%, Sm2O3 13%-31%, Nd2O3 0%-2%, Bi2O3 21%-29%, TiO2 30%-36%, and La2O3 0.5%-0.7%.

10. The composite ceramic capacitor according to claim 8 or 9, characterized in that: The preparation method of the ceramic capacitor core material comprises 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: drying the primary mixture and pre-burning it to obtain a pre-burned mixture, the pre-burning temperature is 1150°C-1250°C, and the pre-burning time is 2-5 hours; Step 4: Mix the pre-burned mixture and water in a mass ratio of 1:0.5-0.8, add PVA, and then grind for the second time to obtain a secondary mixture. The second grinding time is 3-12 hours, and the mass ratio of PVA to the mass of the secondary mixture is 0.5%-3%; Step 5: spray granulate the secondary mixture to obtain a granular material 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 100kg of granular materials to 30min±10min, and control the water content of the granular materials to 0.1%-0.5%, to obtain ceramic capacitor core materials.

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