High-bandwidth current transformer

Abstract

The invention relates to a high-bandwidth current transformer. The transformer comprises a transformer body, the transformer body comprises a transformer shell and a winding assembly arranged in the transformer shell, the winding assembly at least comprises a winding unit, the winding unit at least comprises a plurality of turns of windings, and a corresponding winding inductor is formed based on one or more turns of windings; the assembling state of winding units in the winding assembly in the mutual inductor shell is configured, so that parasitic balance capacitance used for balancing the winding inductance corresponding to each turn of winding is generated; and the distributed assembly is assembled on the winding assembly and comprises a plurality of distributed elements, and one distributed element is adaptively connected with the winding of the corresponding turn in the winding unit so as to realize impedance matching between the winding inductor and the parasitic capacitor. According to the invention, the frequency band width and the measurement precision of the current transformer can be effectively improved, and the assembly difficulty is reduced.

Description

Technical Field

[0001] The present invention relates to a current transformer for current measurement, in particular to a high-bandwidth current transformer. Background Art

[0002] Current transformers have the advantage of isolated measurement, but generally speaking, their bandwidth is limited and their high-frequency measurement capabilities are limited. Specifically, the frequency band of a current transformer refers to its ability to accurately measure the current frequency range, that is, the frequency range within which it can maintain high precision and stability. The bandwidth determines the measurement accuracy and response speed of the current transformer at different frequencies and is one of its key performance parameters.

[0003] The structure of the current transformer is that the winding wire is wound around the magnetic core. Therefore, it can be seen that leakage inductance is inevitable when the current transformer is working. In addition, there is also parasitic capacitance between the winding wire and the casing, and there is also parasitic capacitance between the turns within the winding wire. These parasitic inductances and capacitances will affect the frequency characteristics, resulting in the bandwidth of the current transformer being limited, and the upper frequency limit is difficult to expand. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a high-bandwidth current transformer. By means of a segmented impedance matching design, the parasitic inductance and parasitic capacitance are balanced and the output impedance is matched, which can effectively improve the frequency bandwidth and measurement accuracy of the current transformer.

[0005] According to the technical solution provided by the present invention, a high-bandwidth current transformer comprises:

[0006] The transformer body includes a transformer housing and a winding assembly arranged in the transformer housing, wherein:

[0007] The winding assembly comprises at least a winding unit, wherein the winding unit comprises at least a plurality of winding turns 10, and a corresponding winding inductance is formed based on one or more winding turns;

[0008] Configuring an assembly state of winding units in a winding assembly within a transformer housing to generate a parasitic balancing capacitor group, wherein the parasitic balancing capacitor group includes a plurality of parasitic balancing capacitors, wherein the parasitic balancing capacitors in the parasitic balancing capacitor group correspond one-to-one to the winding inductance formed by the winding units, so that a corresponding winding inductance is balanced by a parasitic balancing capacitor;

[0009] The distributed component is mounted on the winding component and includes a plurality of distributed elements, wherein a distributed element is adaptively connected to the winding of the corresponding turn in the winding unit to achieve impedance matching with the winding inductance and parasitic capacitance.

[0010] The distributed elements in the distributed component include at least distributed resistors, wherein:

[0011] When the distributed element adopts a distributed resistor, the distributed resistor is assembled on the component carrier, and the distributed resistor is assembled on the winding component through the component carrier, so that the distributed resistor on the component carrier is in a surrounding state on the winding component, and each distributed resistor is configured to be electrically connected to the corresponding turn of the winding.

[0012] The component carrier at least includes a flexible PCB board, wherein:

[0013] When the component carrier is a flexible PCB, the distributed resistors are distributed on the first surface of the flexible PCB, and a resistance pad unit corresponding to each distributed resistor is provided on the second surface of the flexible PCB, wherein the resistance pad unit includes at least two resistance pads, and the two resistance pads are respectively electrically connected to the ends of the corresponding distributed resistors;

[0014] When the distributed resistor is electrically connected to the winding of the corresponding turn, at least the winding of the corresponding turn is welded to the resistance pad of the corresponding distributed resistor.

[0015] After each distributed resistor is electrically connected to the corresponding turn of the winding, the multiple distributed resistors adapted to be connected to the corresponding turn of the winding are connected in series;

[0016] The component carrier is also provided with a measurement accuracy adjustment unit for adjusting the output accuracy, wherein:

[0017] The measurement accuracy adjustment unit is connected to one end of the distributed resistance string, and during current mutual induction, the measurement accuracy adjustment unit and the current mutual induction load are in parallel.

[0018] The measurement accuracy adjustment unit includes at least one accuracy adjustment resistor, wherein:

[0019] When the measurement accuracy adjustment unit adopts an accuracy adjustment resistor, one end of the accuracy adjustment resistor is connected to one end of the distributed resistor string, and the other end of the accuracy adjustment resistor is grounded.

[0020] The winding assembly further includes a winding frame and a winding core assembled in the winding frame, wherein:

[0021] The component carrier is assembled on the winding frame, the winding unit is wound on the winding frame and the component carrier, and the winding unit is in contact with the component carrier.

[0022] The winding frame includes a frame lower shell and a frame upper shell adapted to the frame lower shell, wherein:

[0023] The upper frame shell and the lower frame shell are aligned and connected, and the component carrier surrounds the aligned upper frame shell and the lower frame shell, and the component carrier surrounds and covers at least the joint between the upper frame shell and the lower frame shell;

[0024] The distributed resistor is located in a groove on one side surface of the component carrier adjacent to the joint of the upper shell of the skeleton and the lower shell of the skeleton.

[0025] At least one skeleton support positioning member is also provided on the winding skeleton, and the winding skeleton is aligned and assembled in the transformer housing through the skeleton support positioning member to configure the assembly state of the winding unit in the transformer housing and generate corresponding parasitic balancing capacitance.

[0026] The mutual inductor housing includes a mutual inductor lower shell and a mutual inductor upper shell adapted to the mutual inductor lower shell, wherein:

[0027] A skeleton sleeve is provided in the mutual inductance lower shell, and a skeleton assembly positioning piece adapted to the skeleton support positioning piece is provided in the mutual inductance lower shell;

[0028] When assembling the winding skeleton in the transformer housing, the winding skeleton is placed on the skeleton sleeve, and the skeleton support positioning piece and the skeleton assembly positioning piece are aligned and connected to each other, so that the winding skeleton is aligned and assembled in the mutual inductance lower shell, and the winding unit is assembled in the transformer housing.

[0029] A mutual inductance housing hole penetrating the mutual inductance housing is provided in the mutual inductance housing, an insulating sleeve is provided in the mutual inductance housing hole, and the winding assembly is formed in the mutual inductance housing in a state of being sleeved on the insulating sleeve.

[0030] The advantages of the present invention are as follows: the winding units in the winding assembly are configured to be assembled in the transformer housing to generate a parasitic balancing capacitor group, and the corresponding winding inductance is balanced by the parasitic balancing capacitors in the parasitic balancing capacitor group. When the parasitic capacitance is insufficient to achieve balance, the balance can be increased by the distributed capacitance and / or distributed resistance in the distributed assembly, and connected to the winding units to achieve an impedance matching state, thereby expanding the frequency bandwidth of the current transformer and improving the current measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a three-dimensional diagram of an embodiment of a high-bandwidth current transformer of the present invention.

[0032] Figure 2 This is a schematic structural diagram of an embodiment of the present invention after removing the upper shell of the mutual inductance.

[0033] Figure 3 This is a structural diagram of an embodiment of the mutual inductance lower shell of the present invention.

[0034] Figure 4This is a structural diagram of an embodiment of the corresponding position state of the winding assembly and the insulating sleeve of the present invention.

[0035] Figure 5 This is a structural diagram of an embodiment of the coordination between the distributed components and the winding frame of the present invention.

[0036] Figure 6 This is a structural diagram of an embodiment of the present invention in which the distributed components cooperate with the lower shell of the skeleton.

[0037] Figure 7 This is a schematic structural diagram of an embodiment of the skeleton upper shell of the present invention.

[0038] Figure 8 This is a schematic structural diagram of an embodiment of the lower shell of the skeleton of the present invention.

[0039] Figure 9 This is a partially enlarged view of an embodiment of the present invention in which the winding, distributed components, and skeleton housing are matched.

[0040] Figure 10 This is a schematic diagram of the structure of an embodiment of the distributed component of the present invention.

[0041] Figure 11 Schematic diagram of the equivalent circuit of the current transformer of the present invention.

[0042] Figure 12 This is a schematic diagram of an embodiment of the present invention that achieves impedance matching in conjunction with winding inductance.

[0043] Explanation of the accompanying drawings: 1-mutual inductance lower shell, 2-mutual inductance upper shell, 3-mutual inductance joint, 4-mutual inductance shell hole, 5-winding assembly, 6-insulating sleeve, 7-skeleton sleeve, 8-skeleton support positioning piece, 9-flexible PCB board, 10-winding, 11-skeleton hole, 12-skeleton upper shell, 13-skeleton lower shell, 14-upper support positioning body, 15-lower support positioning body, 16-skeleton lower shell outer cylinder, 17-skeleton lower shell inner cylinder, 18-skeleton support positioning groove, 19-resistance pad, 20-distributed resistor, 21-mutual inductance lower shell outer cylinder, 22-mutual inductance lower shell hole, 23-resistance via, 24-skeleton assembly positioning groove, 25-carrier support table. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to specific drawings and embodiments.

[0045] In order to effectively improve the frequency bandwidth and measurement accuracy of a current transformer, the present invention provides a high-bandwidth current transformer. Specifically, the high-bandwidth current transformer includes:

[0046] The transformer body includes a transformer housing and a winding assembly 5 arranged in the transformer housing, wherein:

[0047] The winding assembly 5 at least includes a winding unit, and the winding unit at least includes a plurality of winding turns 10, and a corresponding winding inductance is formed based on one or more winding turns 10;

[0048] Configuring the assembly state of the winding units in the winding assembly 5 within the transformer housing to generate a parasitic balancing capacitor group, wherein the parasitic balancing capacitors in the parasitic balancing capacitor group correspond one-to-one to the winding inductance formed by the winding units, so that one parasitic balancing capacitor is used to balance the corresponding winding inductance;

[0049] The distributed component is mounted on the winding component 5 and includes a plurality of distributed elements, wherein one distributed element is adaptively connected to the winding 10 of the corresponding turn in the winding unit to achieve impedance matching with the winding inductance and parasitic capacitance.

[0050] Specifically, the transformer body is the main body of the current transformer. The transformer body can adopt an existing commonly used form, specifically based on whether it can meet the demand for current measurement through current mutual induction. Generally, the transformer body should at least include a transformer housing and a winding assembly 5 located in the transformer housing, that is, the transformer housing 1 can accommodate the winding assembly 5, and the winding assembly 5 is a component with current mutual induction capability. Figure 1 An embodiment of the current transformer of the present invention is shown in FIG. Figure 2 FIG. 5 shows an embodiment in which the winding assembly 5 is located in a transformer housing. Generally, the transformer housing can be a metal housing.

[0051] Generally, the winding assembly 5 should include at least a winding unit, which can include a plurality of turns of a winding 10. For example, the winding unit can be formed by winding a single winding wire. When the winding unit is formed, each turn of the winding wire can form a winding 10. The method of forming the winding unit using the winding wire can be consistent with the existing technology and will not be described in detail here. In specific implementations, the number of windings 10 included in the winding unit can be selected according to actual needs to meet the actual current measurement requirements.

[0052] It should be noted that the higher the signal frequency, the shorter the wavelength. For current transformers, the signal frequency refers to the frequency of the measured bus current. Specifically, the total length of the winding wire is relatively long. As the bus current frequency increases, the wavelength of the corresponding induced electromagnetic wave can be equivalent to or less than the length of the winding wire. Therefore, at high frequencies, the winding unit formed by the winding wire cannot be regarded as a lumped element and should be regarded as a distributed device. Generally, when the winding wire length is greater than one-quarter of the wavelength of the electromagnetic wave, the winding unit must be regarded as a distributed device.

[0053] When the winding unit is regarded as a distributed device, a section of winding target line is formed based on one or more turns of winding 10, and the formed section of winding target line can correspond to a winding inductance, and based on the way of winding the winding wire to form a single winding line, it can be known that the winding inductance formed by all the sections of winding target line forms a series connection state. Figure 11 , an embodiment in which a winding unit includes N segments of winding target lines is shown. In this case, N winding inductors can be formed accordingly. In the figure, the N winding inductors are winding inductance L1, winding inductance L2, ..., winding inductance LN, and winding inductances L1 to winding inductance LN are connected in series.

[0054] It can be seen from the above background technology that after the winding assembly 5 is assembled in the transformer housing, parasitic capacitance will be formed between the winding unit and the transformer housing, as well as between each turn of the winding 10 in the winding unit. It should be understood that the parasitic capacitance formed is related to the assembly state of the winding assembly 5 in the transformer housing, wherein the assembly state of the winding assembly 5 in the transformer housing at least includes the assembly position of the winding assembly 5 in the transformer housing; therefore, after determining the winding inductance formed by the above-mentioned section of the winding target line, a parasitic balanced capacitance group can be generated by configuring the assembly state of the winding unit in the winding assembly 5 in the transformer housing. In specific implementation, the generated parasitic balanced capacitance group should be connected correspondingly to the winding inductance formed by the above-mentioned section of the winding target line in the winding unit. The corresponding connection state will be referred to below. Figure 11 Give an example.

[0055] Specifically, the parasitic balancing capacitor group may include a plurality of parasitic balancing capacitors, thereby balancing the winding inductance using the parasitic balancing capacitors. Figure 11 In the figure, capacitors Cx0, Cx1, ..., and CxN are N+1 parasitic balancing capacitors in the parasitic balancing capacitor group. As shown in the figure, when balancing the winding inductance, they need to be connected correspondingly to the winding inductance, such as Figure 11 In the circuit, one end of capacitor Cx0 is connected to one end of winding inductor L1, the other end of capacitor Cx0 is grounded, the other end of capacitor Cx1 is connected to the other end of winding inductor L1 and one end of winding inductor L2, the other end of capacitor Cx1 is grounded, and the rest of the cases can be referred to Figure 11 and instructions here.

[0056] In one embodiment of the present invention, a distributed component is further provided on the winding component 5, and the distributed component includes a plurality of distributed elements. The number of distributed elements in the distributed component can be selected according to needs. For example, the number of distributed elements can be consistent with the number of turns in the winding unit. In this case, the number of distributed elements is consistent with the number of winding inductors. Of course, the number of distributed elements can also be less or more than the number of winding inductors. The number of distributed elements can be selected according to actual needs.

[0057] In specific implementations, the distributed component is positioned on the winding assembly 5 and adaptively connected to the corresponding winding 10 within the winding unit, thereby achieving adaptive connection with the corresponding winding inductance and parasitic capacitance, thereby achieving impedance matching. It should be noted that in the impedance matching state, the reflected wave is minimized, the waveform quality of the incident wave is optimized, and the fastest signal rising or falling edge can be achieved, thereby achieving a wider bandwidth and expanding the frequency bandwidth of the current transformer. For details on the incident and reflected waves, please refer to the following corresponding descriptions.

[0058] As can be seen from the above description, the present invention balances the corresponding winding inductance by means of parasitic balancing capacitors in the parasitic balancing capacitor group, and achieves impedance matching by connecting the distributed components with the winding units, thereby expanding the frequency bandwidth of the current transformer.

[0059] In one embodiment of the present invention, the distributed elements in the distributed assembly include at least a distributed resistor 20, wherein:

[0060] When the distributed element adopts a distributed resistor 20, the distributed resistor 20 is assembled on the component carrier, and the distributed resistor 20 is assembled on the winding component 5 through the component carrier, so that the distributed resistor 20 on the component carrier is in a surrounding state on the winding component 5, and each distributed resistor 20 is configured to be electrically connected to the corresponding turn of the winding 10.

[0061] In a specific implementation, the distributed element can be a distributed resistor 20, wherein the distributed resistor 20 specifically refers to a resistor distributed on the component carrier. The distributed resistor 20 can adopt an existing commonly used resistor form, such as a high-precision, low temperature coefficient resistor to improve the stability of the distributed resistor 20. In order to facilitate corresponding electrical connection with the corresponding turn winding 10, thereby achieving adaptive connection with the corresponding winding inductance, the distributed resistor 20 is preferably distributed along the length of the component carrier. Therefore, the distributed resistor 20 can be assembled on the winding assembly 5 through the component carrier, and all the distributed resistors 20 are in a surrounding state on the winding assembly 5. Specifically, assembling the distributed resistor 20 on the winding assembly 5 specifically means that all the distributed resistors 20 on the component carrier are assembled on the winding assembly 5.

[0062] It should be noted that when all distributed components 20 are assembled on the winding component 5, all distributed resistors 20 are in a surrounding state on the winding component 5, that is, different distributed resistors 20 are distributed at different positions on the winding component 5, thereby conveniently electrically connecting the corresponding turns of the winding 10 with the corresponding distributed resistor 20.

[0063] It should be understood that after determining the winding inductance corresponding to the winding 10, the inductance value corresponding to the winding inductance and the corresponding winding wire internal resistance can be determined; in addition, based on the assembly state of the winding unit in the winding assembly 5 in the transformer housing, the size of the corresponding parasitic capacitance can be determined using existing commonly used technical methods, and thereafter, the resistance value required for impedance matching can be determined.

[0064] After determining the resistance required for impedance matching, the corresponding resistance value of a distributed resistor 20 can be determined. Specifically, the impedance matching process described above can be described using the telegraph equation. The telegraph equation reflects the distribution and propagation characteristics of energy in a transmission line and is the basis for analyzing high-frequency signal transmission. It is a second-order partial differential equation whose solution is usually in the form of a wave, including an incident wave and a reflected wave. Specifically, the incident wave is an electromagnetic wave generated by the bus current, and the reflected wave is an electromagnetic wave formed by reflection during the propagation of the electromagnetic wave. By solving the telegraph equation, it can be seen that when impedance matching is satisfied, the reflected wave can be minimized to the greatest extent, and a wider bandwidth can be achieved.

[0065] In one embodiment of the present invention, the component carrier comprises at least a flexible PCB board 9, wherein:

[0066] When the component carrier is a flexible PCB 9, the distributed resistors 20 are distributed on the first surface of the flexible PCB 9, and a resistance pad unit corresponding to each distributed resistor 20 is provided on the second surface of the flexible PCB 9, wherein the resistance pad unit includes at least two resistance pads 19, and the two resistance pads 19 are respectively electrically connected to the ends of the corresponding distributed resistors 20;

[0067] When the distributed resistor 20 is electrically connected to the corresponding turn of the winding 10 , at least the corresponding turn of the winding 10 is welded to the resistance pad 19 of the corresponding distributed resistor 20 .

[0068] In order to facilitate assembly on the winding assembly 5, the assembly carrier can preferably adopt a flexible PCB board 9, and the flexible PCB board 9 can adopt an existing commonly used form. By utilizing the flexibility of the flexible PCB board 9, the flexible PCB board 9 can be configured in a ring shape. Figure 10 FIGURE 2 illustrates an embodiment in which the flexible PCB 9 is configured in a circular shape. In this embodiment, multiple distributed resistors 20 are located on the inner surface of the flexible PCB 9, while the resistor pad units are located on the outer surface of the flexible PCB 9. Specifically, the inner surface of the flexible PCB 9 serves as the first surface, and the outer surface of the flexible PCB 9 serves as the second surface. In practice, when the flexible PCB 9 is used as the component carrier, the flexible PCB 9 can be first configured in an arc shape. The distributed resistors 20 can then be assembled onto the winding assembly 5 in a circular configuration using the flexible PCB 9.

[0069] Figure 4FIG2 shows an embodiment in which a flexible PCB board 9 is assembled on a winding assembly 5. As can be seen from the figure, when the flexible PCB board 9 is assembled on the winding assembly 5, the second surface of the flexible PCB board 9 is exposed, that is, the resistance pad unit is exposed, so that the distributed resistor 20 is electrically connected to the corresponding turn of the winding 10 through the resistance pad unit.

[0070] In a specific implementation, each resistor pad unit should include two resistor pads 19. The two resistor pads 19 can be connected to the two ends of the corresponding distributed resistor 20, that is, the corresponding distributed resistor 20 can be led out through the two resistor pads 19. Because the resistor pad unit and the distributed resistor 20 are located on two corresponding surfaces of the flexible PCB board 9, in order to lead out the distributed resistor 20, a resistor via 23 can be provided on the flexible PCB board 9. The resistor via 23 penetrates the flexible PCB board 9 and allows the lead wires extending from the two ends of the distributed resistor 20 to pass through the resistor via 23 to electrically connect to the corresponding resistor pad 19.

[0071] In one embodiment of the present invention, when the distributed resistor 20 is electrically connected to the corresponding turn of the winding 10, specifically, the corresponding turn of the winding 10 is welded to the resistance pad 19 of the corresponding distributed resistor 20. Figure 9 FIG shows an embodiment of welding the winding 10 to the corresponding resistor pad 19. In a specific implementation, after each distributed resistor is electrically connected to the corresponding turn of the winding, the multiple distributed resistors 20 adapted to be connected to the corresponding turn of the winding are connected in series. Figure 11 FIG. 1 shows an embodiment in which a plurality of distributed resistors 20 are connected in series. Figure 11 It can be seen that the figure shows an embodiment in which a distributed component includes N distributed resistors 20, that is, the number of distributed resistors 20 is consistent with the number of winding inductors. At this time, the distributed resistors 20 and the winding inductors are in one-to-one correspondence.

[0072] Figure 11 In the embodiment, the N distributed resistors 20 are resistor Rx1, resistor Rx2, ..., resistor RxN, wherein one end of the resistor Rx1 is connected to one end of the winding inductor L1 and one end of the capacitor Cx0, and the other end of the resistor Rx1 is connected to one end of the resistor Rx2, the other end of the winding inductor L1, one end of the winding inductor L2, and one end of the capacitor Cx1. The multiple distributed resistors 20 are connected in series and are connected to the winding inductors accordingly. For details, see the following example. Figure 11 and instructions here.

[0073] As can be seen from the above description, the number of distributed resistors 20 can be different from the number of winding inductors. For example, when the number of distributed resistors 20 is less than the number of winding inductors, multiple winding inductors can be configured to correspond to one distributed resistor 20. For example, resistor Rx1 can be configured to correspond to winding inductor L1 and winding inductor L2. In this case, one end of resistor Rx1 is connected to one end of winding inductor L1, and the other end of resistor Rx1 is connected to winding inductor L2 and winding inductor L3. In specific implementation, according to the above description of forming the winding inductor, the inductor of the corresponding turn can be selected and welded to the corresponding resistance pad 19 of the distributed resistor 20. In other words, the specific embodiment of the present invention is based on whether impedance matching can be achieved, and will not be further described here.

[0074] Furthermore, the distributed components within the distributed assembly may also include distributed capacitors. When the parasitic capacitance between the winding wire and the housing is insufficient to achieve balanced compensation, the distributed capacitors within the distributed assembly can be used to increase the equivalent capacitance, achieving better balanced compensation. In specific implementations, the distributed capacitors should be connected in parallel with the corresponding parasitic capacitors.

[0075] As can be seen from the above description, the present invention allows all matching components to be assembled on the flexible PCB 9, including surface-mount distributed resistors and / or distributed capacitors. Distributed resistors can utilize low temperature coefficient resistors, which significantly reduce the temperature coefficient compared to copper materials, resulting in better temperature stability and accuracy drift. Distributed capacitors can be packaged in a miniaturized form, providing higher capacitance.

[0076] Figure 12 In the present invention, a winding segment can be targeted to correspond to a winding inductance, and the winding inductance, the combined capacitance, and the distributed resistance can achieve impedance matching. Specifically, based on the telegraph equation, there can be:

[0077]

[0078] Where U is the terminal voltage at AB or CD, I is the impedance current between AC terminals, γ is the transmission coefficient, and d 2 U is the second-order derivative of the terminal voltage, d 2 I is the second-order derivative of the impedance current, d 2 z is the second derivative of length.

[0079] For the transmission coefficient γ, we have:

[0080]

[0081] Where ω is the signal frequency, L AC is the inductance value of the winding inductance, Rs is the wire resistance that forms the winding inductance, C t is the inter-turn capacitance between winding turns, R R is the distributed resistance, CP is the combined capacitance. Generally, the combined capacitance C P This includes parasitic capacitance and / or distributed capacitance.

[0082] When the above winding inductance is Figure 11 When L1 is in the R Should be Figure 11 Rx1 in the combined capacitor C P At least Figure 11 In Cx1, when the winding inductance is other, you can refer to Figure 11 And here it is explained to determine the corresponding distributed resistance R R And the combined capacitor C P The case of internal parasitic capacitance will not be explained here one by one with examples.

[0083] Based on the above telegraph equation, the corresponding characteristic impedance is:

[0084]

[0085] When the wire resistance Rs is small, the distributed resistance R R Larger and When , the above characteristic impedance Z0 can be simplified to:

[0086] If the current transformer load RL is an oscilloscope, the current transformer load RL is typically 50Ω or 1MΩ. Specifically, at 1MΩ, it often includes a certain amount of capacitance. Typically, the equivalent capacitor is connected in parallel, and the capacitance is in the pF range. It should be noted that the impedance matching state, i.e., the characteristic impedance Z0, is complex conjugate with the current transformer load RL.

[0087] From the above description, it can be seen that when determining the inductance value L of the winding inductance AC Afterwards, when the impedance matching state is to be met, according to the type of the current transformer load RL, the corresponding parasitic capacitance can be further determined by technical means in this technical field, and the required capacitance of the distributed capacitor can be determined until the impedance matching state can be met.

[0088] It should be noted that the high-frequency characteristics of the current transformer require a high number of matching segments, which results in a large number of matching resistors, capacitors, etc., and also requires component precision. If multiple discrete components are used, the workload of assembly and adjustment is very large. The present invention integrates a large number of distributed resistors and / or distributed capacitors on the flexible PCB board 9, with mature technology and high-efficiency mass production. After assembling distributed resistors and distributed capacitors on the flexible PCB board 9, the number of matching components is greatly reduced, processing, assembly, and debugging are greatly simplified, and production efficiency is improved.

[0089] In one embodiment of the present invention, a measurement accuracy adjustment unit for adjusting output accuracy is further provided on the component carrier board, wherein:

[0090] The measurement accuracy adjustment unit is connected to one end of the distributed resistor string, and when current mutual induction is in effect, the measurement accuracy adjustment unit and the current mutual induction load are in parallel. In order to adjust the accuracy of current measurement, a measurement accuracy adjustment unit is also provided on the component carrier. When the component carrier adopts a flexible PCB board 9, the measurement accuracy adjustment unit and the distributed resistor 20 are provided on the flexible PCB board 9 at the same time. A distributed resistor string specifically refers to a series connection state formed by multiple distributed resistors 20, such as Figure 11 In the embodiment shown in FIG, the resistors Rx1 , Rx2 , . . . , and RxN are connected in series to form a distributed resistor string.

[0091] In a specific implementation, the measurement accuracy adjustment unit includes at least one accuracy adjustment resistor, wherein:

[0092] When the measurement accuracy adjustment unit adopts an accuracy adjustment resistor, one end of the accuracy adjustment resistor is connected to one end of the distributed resistor string, and the other end of the accuracy adjustment resistor is grounded.

[0093] Figure 11 FIG2 shows an embodiment in which the measurement accuracy adjustment unit adopts an accuracy adjustment resistor. In the figure, Rp is the accuracy adjustment resistor. One end of the accuracy adjustment resistor is connected to one end of the resistor Rx1, and the other end of the accuracy adjustment resistor is grounded. Of course, when the accuracy adjustment resistor is connected to the resistor Rx1, it is also adaptively connected to the winding inductance L1 and the capacitor Cx0. Figure 11 In the figure, RL is the current transformer load, and the output end of the current transformer is connected to the current transformer load RL.

[0094] When performing current mutual induction, since the precision adjustment resistor Rp is connected in parallel with the distributed resistor string, the shunt ratio flowing to the current mutual induction load RL can be changed by adjusting the resistance value of the precision adjustment resistor Rp, thereby improving the precision of the current mutual induction.

[0095] In one embodiment of the present invention, the winding assembly 5 further includes a winding frame and a winding core assembled in the winding frame, wherein:

[0096] The component carrier is assembled on the winding frame, the winding unit is wound on the winding frame and the component carrier, and the winding unit is in contact with the component carrier.

[0097] Figure 2 and Figure 4An embodiment of the winding assembly 5 is shown in FIG. As can be seen from the figure, the winding assembly 5 should include a winding bobbin, a winding core, and a winding unit. The winding core is located inside the winding bobbin, and the winding unit is wound on the winding bobbin using winding wire. The form of the winding core, the winding bobbin, and the winding unit forming the winding assembly 5 can be consistent with the existing technology, so as to meet the mutual inductance operation when the current is measured through the winding assembly 5. It should be noted that the situation of the winding core inside the winding bobbin is not shown in the figure. The situation of the winding core can be determined in combination with the description of the winding bobbin below, specifically based on whether it can be assembled in the winding bobbin and form the required winding assembly 5.

[0098] From the above description, it can be seen that the component carrier can be a flexible PCB board 9. When the component carrier is a flexible PCB board 9, the flexible PCB board 9 can be first wrapped around the winding frame, such as Figure 5 As shown, thereafter, the winding wire is wound on the winding frame. When the winding wire is wound on the winding frame, it is also wound on the flexible PCB board 9, and the winding unit formed by the winding wire is also in contact with the flexible PCB board 9. Of course, the winding unit is also in contact with the winding frame, as shown in FIG. Figure 4 and Figure 9 shown.

[0099] In one embodiment of the present invention, the winding frame includes a frame lower shell 13 and a frame upper shell 12 adapted to the frame lower shell 13, wherein:

[0100] The skeleton upper shell 12 and the skeleton lower shell 13 are aligned and connected, and the component carrier surrounds the aligned skeleton upper shell 12 and the skeleton lower shell 13, and the component carrier surrounds and covers at least the joint between the skeleton upper shell 12 and the skeleton lower shell 13;

[0101] The distributed resistor 20 is located on one side of the component carrier adjacent to the junction of the upper frame shell 12 and the lower frame shell 13 .

[0102] Figure 4 and Figure 5 An embodiment of a winding frame is shown in FIG. As can be seen from the figure, the winding frame can be formed by the frame lower shell 13 and the frame upper shell 12. As can be seen from the figure, the winding frame is annular, and the central area of ​​the winding frame has a frame hole 11, and the frame hole 11 passes through the winding frame. When the winding unit is wound on the winding frame, the winding wire will pass through the frame hole 11 and be wound along the circumference of the winding frame. The situation of the winding unit being wound on the winding frame can be referred to Figure 2 and Figure 4 As shown, the manner of winding the winding wire on the winding frame and forming the winding unit is consistent with the prior art and will not be described in detail here.

[0103] The winding frame is generally made of insulating material, that is, the frame lower shell 13 and the frame upper shell 12 are generally made of insulating material. Figure 2 and Figure 3 As can be seen from the above description, the winding component 5 is first aligned and connected with the skeleton upper shell 12 and the skeleton lower shell 13, and then the component carrier of the flexible PCB board 9 is wrapped around the aligned and connected skeleton upper shell 12 and the skeleton lower shell 13, and the flexible PCB board 9 at least wraps around and covers the joint between the skeleton upper shell 12 and the skeleton lower shell 13.

[0104] Depend on Figure 4 、 Figure 5 and Figure 6 It can be seen that when the flexible PCB board 9 surrounds and covers the joint between the skeleton upper shell 12 and the skeleton lower shell 13, the first surface of the flexible PCB board 9 forms the inner surface of the flexible PCB board 9, and the second surface of the flexible PCB board 9 forms the outer surface of the flexible PCB board 9, that is, the resistor pad unit on the flexible PCB board 9 is in an outer surface exposed state.

[0105] Figure 8 An embodiment of the skeleton lower shell 13 is shown in the figure. As can be seen from the figure, the skeleton lower shell 13 is also in a circular shape. The skeleton lower shell 13 includes a skeleton lower shell inner cylinder 17 located in the inner circle and a skeleton lower shell outer cylinder 16 located in the outer circle. The skeleton lower shell outer cylinder 16 surrounds the skeleton lower shell inner cylinder 17. Generally, the skeleton lower shell outer cylinder 16 and the skeleton lower shell inner cylinder 17 are concentrically distributed. The skeleton lower shell inner cylinder 17 is hollow, and one end of the skeleton lower shell outer cylinder 16 is open. Figure 8 In the embodiment, a carrier support table 25 is provided on the outer wall of the outer cylinder 16 of the lower shell of the skeleton, and the carrier support table 25 can be used to support the flexible PCB board 9, such as Figure 6 shown. Figure 6 In the embodiment, the flexible PCB board 9 is in an annular shape and is supported on the carrier support table 25. At this time, the flexible PCB board 9 surrounds the outer cylinder 16 of the lower shell of the skeleton.

[0106] Figure 7 An embodiment of the skeleton upper shell 12 is shown in FIG. As can be seen from the figure, the shape of the skeleton upper shell 12 should be adapted to the skeleton lower shell 13 so that the skeleton upper shell 12 can be aligned and pressed onto the skeleton lower shell 13. Specifically, when the skeleton upper shell 12 is aligned and pressed onto the skeleton lower shell 13, the skeleton upper shell 12 can at least be sleeved on the tube mouth of the outer sleeve 16 of the skeleton lower shell, and the flexible PCB board 9 is generally placed between the carrier support table 25 and the skeleton upper shell 12, as shown in FIG. Figure 5 As shown, the joint between the skeleton upper shell 12 and the skeleton lower shell 13 at least includes the area where the skeleton upper shell 12 is sleeved on the sleeve opening of the skeleton lower shell outer sleeve 16.

[0107] In specific implementation, when the winding core is placed in the winding frame, the winding core can be assembled in the frame lower shell 13 through the inner cylinder 17 of the frame lower shell, and when the frame upper shell 12 is aligned and pressed on the frame lower shell 13, the winding core can be sealed in the winding frame.

[0108] In one embodiment of the present invention, at least one skeleton support positioning member 8 is further provided on the winding skeleton, and the winding skeleton is aligned and assembled in the transformer housing through the skeleton support positioning member 8 to configure the assembly state of the winding unit in the transformer housing and generate corresponding parasitic balancing capacitance.

[0109] From the above description, it can be seen that in order to generate the required parasitic balancing capacitance, the assembly state of the winding unit in the transformer housing can be configured. The assembly state of the winding unit in the transformer housing can refer to the above description. In order to ensure the accuracy and stability of the assembly state of the winding unit in the transformer housing, a skeleton support positioning piece can be set on the winding skeleton, and the skeleton support positioning piece can be used to align the assembly in the transformer housing. Figure 5 、 Figure 6 、 Figure 7 and Figure 8 The skeleton supporting and positioning member of the present invention will be described as an example.

[0110] like Figures 5 to 8 It can be seen that three skeleton support positioning members 8 are arranged on the skeleton winding, and the three skeleton support positioning members 8 are evenly distributed. Specifically, each skeleton support positioning member 8 may include an upper support positioning body 14 and a lower support positioning body 15, wherein the upper support positioning body 14 is arranged on the skeleton upper shell 12, and the lower support positioning body 15 is arranged on the skeleton lower shell 13. The upper support positioning body 14 may be L-shaped, and the first part of the upper support positioning body 14 is located on the end face of the skeleton upper shell 12, and the second part of the upper support positioning body 14 is located in the skeleton upper shell hole of the skeleton upper shell 12, and the skeleton upper shell hole passes through the skeleton upper shell 12.

[0111] During specific implementation, the shape of the lower support positioning body 15 can be consistent with the upper support positioning body 14, that is, the lower support positioning body 15 can also be L-shaped. The first part of the lower support positioning body 15 is located on the inner wall of the inner cylinder 17 of the lower shell of the skeleton, and is distributed along the length direction of the inner cylinder 17 of the lower shell of the skeleton. The second part of the lower support positioning body 15 is located on the end face of the lower shell of the skeleton 13.

[0112] In order to facilitate the alignment and connection between the skeleton upper shell 12 and the skeleton lower shell 13, a skeleton support positioning groove 18 can be set on the upper end surface of the inner cylinder 17 of the skeleton lower shell. The skeleton support positioning groove 18 allows the alignment and embedding of the second part of the upper support positioning body 14. When the second part of the upper support positioning body 14 is embedded in the skeleton support positioning groove 18, the alignment and connection between the skeleton upper shell 12 and the skeleton lower shell 13 can be achieved. In addition, when the second part of the upper support positioning body 14 is embedded in the skeleton support positioning groove 18, the second part of the upper support positioning body 14 is in a positive corresponding state with the first part of the lower support positioning body 15, as shown in FIG. Figure 5 As shown in the figure, the first part of the upper support positioning body 14 and the second part of the lower support positioning body 15 are distributed and protrude from the corresponding surface of the winding skeleton.

[0113] In one embodiment of the present invention, the mutual inductor housing includes a mutual inductor lower housing 1 and a mutual inductor upper housing 2 adapted to the mutual inductor lower housing 1, wherein:

[0114] A skeleton sleeve 7 is provided in the mutual inductance lower shell 1, and a skeleton assembly positioning piece adapted to the skeleton support positioning piece 8 is provided in the mutual inductance lower shell 2;

[0115] When assembling the winding skeleton in the transformer housing, the winding skeleton is placed on the skeleton sleeve 7, and the skeleton support positioning piece 8 and the skeleton assembly positioning piece are aligned and connected with each other to align the winding skeleton and assemble it in the lower shell of the transformer, and achieve the assembly state of the winding unit in the transformer housing.

[0116] Figure 1 FIG2 shows an embodiment of a transformer housing. As can be seen from the figure, the transformer housing is annular or quasi-annular in shape. Of course, the shape of the transformer housing should be such that it does not affect the loading of the winding assembly 5 within the transformer housing. In a specific implementation, the transformer housing may include a transformer lower housing 1 and a mutual inductor upper housing 2. The mutual inductor upper housing 2 may be aligned and connected to the mutual inductor lower housing 1. That is, when the mutual inductor upper housing 2 and the mutual inductor lower housing 1 are aligned and connected, the transformer housing is formed.

[0117] Figure 2 and Figure 3 An embodiment of the mutual inductance lower shell 1 is shown in the figure. As can be seen from the figure, the shape of the mutual inductance lower shell 1 can be similar to the shape of the above-mentioned skeleton lower shell 13. Specifically, the mutual inductance lower shell 1 may include a skeleton sleeve 7 located in the central area and a mutual inductance lower shell outer cylinder 21 located on the outer ring of the skeleton sleeve 7. The skeleton sleeve 7 is hollow, and the mutual inductance lower shell outer cylinder 21 is connected to the outer ring of the skeleton sleeve 7, and one end of the skeleton sleeve 7 is connected to the end plate of the mutual inductance lower shell outer cylinder 21. Figure 3 shown.

[0118] In order to be able to adapt and connect with the skeleton support positioning member 8, a skeleton assembly positioning member can be set in the mutual inductance lower shell 1. When the skeleton support positioning member 8 adopts the above form, Figure 3 An embodiment of a skeleton assembly positioning member is shown in the figure. In the figure, the skeleton assembly positioning member can be a skeleton assembly positioning groove 24. The skeleton assembly positioning groove 24 is located between the skeleton sleeve 7 and the outer cylinder 21 of the mutual inductance lower shell. The skeleton assembly positioning groove 24 allows the first part of the upper support positioning body 15 to be embedded. When the first part of the upper support positioning body 15 is embedded in the skeleton assembly positioning groove 24, the skeleton support positioning member 8 and the skeleton assembly positioning member can be aligned and connected with each other, thereby realizing the alignment and assembly of the winding skeleton in the mutual inductance lower shell, and achieving the assembly state of the winding unit configured in the mutual inductance shell.

[0119] Figure 2 In the embodiment, the winding bobbin should be placed on the bobbin sleeve 7, and the second portion of the upper support and positioning body 14 and the first portion of the lower support and positioning body 15 should both be in contact with the outer wall of the bobbin sleeve 7. Generally, when assembling the winding bobbin into the transformer housing, the winding bobbin can be first assembled into the transformer lower housing 1. When assembling the winding bobbin into the transformer lower housing 1, the winding bobbin can be placed on the bobbin sleeve 7, and then the first portion of the upper support and positioning body 15 can be embedded in the bobbin assembly positioning groove 24. At this point, the winding bobbin can be assembled into the transformer lower housing 1.

[0120] In one embodiment of the present invention, a mutual inductance housing hole 4 is provided in the mutual inductance housing and passes through the mutual inductance housing, and an insulating sleeve 6 is provided in the mutual inductance housing hole 4, and the winding assembly is formed in the mutual inductance housing in a state of being sleeved on the insulating sleeve 6.

[0121] Depend on Figure 1 It can be seen that a transformer housing hole 4 is provided in the central area of ​​the transformer housing, and the transformer housing hole 4 passes through the transformer housing so that the transformer housing hole 4 can be placed on the busbar of the current to be measured. In specific implementation, the transformer housing hole 4 can correspond to the through hole passing through the skeleton sleeve 7.

[0122] Figure 1In the transformer housing hole 4, an insulating sleeve 6 is also provided. The size of the insulating sleeve 6 is adapted to the transformer housing 4. After the insulating sleeve 6 is located in the transformer housing hole 4, the insulating sleeve 6 can contact the inner wall of the skeleton sleeve 7. The insulating sleeve 6 can prevent the mutual inductance lower shell 1 and the mutual inductance upper shell 2 from forming a current path around the iron core, thereby avoiding the occurrence of short-circuited turns. The mutual inductance lower shell 1 and the mutual inductance upper shell 2 are both made of metal, and are separated only by a very thin insulating sleeve 6 to realize a Faraday cage structure. There is only a narrow gap at the insulating sleeve 6. The metal on both sides of the insulating sleeve 6 are interlaced with each other, making it difficult for external electromagnetic interference to invade, and a good shielding effect can be achieved. Specifically, the metal on both sides of the insulating sleeve 6 refers to the skeleton sleeve 7 and the portion of the mutual inductance upper shell 2 embedded in the insulating sleeve 6.

[0123] Figure 1 In the figure, a mutual inductance connector 3 is further provided on the mutual inductance lower shell 1, through which the ends of the winding wires wound to form the winding units can be led out so as to be connected to an external circuit. The specific connection with the external circuit can be consistent with the existing technology, so as to meet the requirements for current mutual inductance measurement.

Claims

1. A high-bandwidth current transformer, characterized in that: The high-bandwidth current transformer comprises: The transformer body includes a transformer housing and a winding assembly arranged in the transformer housing, wherein: The winding assembly comprises at least a winding unit, wherein the winding unit comprises at least a plurality of winding turns 10, and a corresponding winding inductance is formed based on one or more winding turns; Configuring an assembly state of winding units in a winding assembly within a transformer housing to generate a parasitic balancing capacitor group, wherein the parasitic balancing capacitor group includes a plurality of parasitic balancing capacitors, wherein the parasitic balancing capacitors in the parasitic balancing capacitor group correspond one-to-one to the winding inductance formed by the winding units, so that a corresponding winding inductance is balanced by a parasitic balancing capacitor; The distributed component is mounted on the winding component and includes a plurality of distributed elements, wherein a distributed element is adaptively connected to the winding of the corresponding turn in the winding unit to achieve impedance matching with the winding inductance and parasitic capacitance.

2. The high-bandwidth current transformer according to claim 1, characterized in that: The distributed elements in the distributed component include at least distributed resistors, wherein: When the distributed element adopts a distributed resistor, the distributed resistor is assembled on the component carrier, and the distributed resistor is assembled on the winding component through the component carrier, so that the distributed resistor on the component carrier is in a surrounding state on the winding component, and each distributed resistor is configured to be electrically connected to the corresponding turn of the winding.

3. The high-bandwidth current transformer according to claim 2, characterized in that: The component carrier at least includes a flexible PCB board, wherein: When the component carrier is a flexible PCB, the distributed resistors are distributed on the first surface of the flexible PCB, and a resistance pad unit corresponding to each distributed resistor is provided on the second surface of the flexible PCB, wherein the resistance pad unit includes at least two resistance pads, and the two resistance pads are respectively electrically connected to the ends of the corresponding distributed resistors; When the distributed resistor is electrically connected to the winding of the corresponding turn, at least the winding of the corresponding turn is welded to the resistance pad of the corresponding distributed resistor.

4. The high-bandwidth current transformer according to claim 2, wherein each After the distributed resistors are electrically connected to the corresponding turns of the winding, the multiple distributed resistors adapted to be connected to the corresponding turns of the winding are connected in series; The component carrier is also provided with a measurement accuracy adjustment unit for adjusting the output accuracy, wherein: The measurement accuracy adjustment unit is connected to one end of the distributed resistance string, and during current mutual induction, the measurement accuracy adjustment unit and the current mutual induction load are in parallel.

5. The high-bandwidth current transformer according to claim 4, characterized in that: The measurement accuracy adjustment unit includes at least one accuracy adjustment resistor, wherein: When the measurement accuracy adjustment unit adopts an accuracy adjustment resistor, one end of the accuracy adjustment resistor is connected to one end of the distributed resistor string, and the other end of the accuracy adjustment resistor is grounded.

6. The high-bandwidth current transformer according to any one of claims 2 to 5, characterized in that: The winding assembly further includes a winding frame and a winding core assembled in the winding frame, wherein: The component carrier is assembled on the winding frame, the winding unit is wound on the winding frame and the component carrier, and the winding unit is in contact with the component carrier.

7. The high-bandwidth current transformer according to claim 6, characterized in that: The winding frame includes a frame lower shell and a frame upper shell adapted to the frame lower shell, wherein: The upper frame shell and the lower frame shell are aligned and connected, and the component carrier surrounds the aligned upper frame shell and the lower frame shell, and the component carrier surrounds and covers at least the joint between the upper frame shell and the lower frame shell; The distributed resistor is located in a groove on one side surface of the component carrier adjacent to the joint of the upper shell of the skeleton and the lower shell of the skeleton.

8. The high-bandwidth current transformer according to claim 7, characterized in that: At least one skeleton support positioning member is further provided on the winding skeleton, and the winding skeleton is aligned and assembled in the transformer housing through the skeleton support positioning member to configure the assembly state of the winding unit in the transformer housing and generate corresponding parasitic balancing capacitance.

9. The high-bandwidth current transformer according to claim 8, characterized in that: The mutual inductor housing includes a mutual inductor lower shell and a mutual inductor upper shell adapted to the mutual inductor lower shell, wherein: A skeleton sleeve is provided in the mutual inductance lower shell, and a skeleton assembly positioning piece adapted to the skeleton support positioning piece is provided in the mutual inductance lower shell; When assembling the winding skeleton in the transformer housing, the winding skeleton is placed on the skeleton sleeve, and the skeleton support positioning piece and the skeleton assembly positioning piece are aligned and connected to each other, so that the winding skeleton is aligned and assembled in the mutual inductance lower shell, and the winding unit is assembled in the transformer housing.

10. The high-bandwidth current transformer according to any one of claims 1 to 5, characterized in that: A mutual inductance housing hole penetrating the mutual inductance housing is provided in the mutual inductance housing, an insulating sleeve is provided in the mutual inductance housing hole, and the winding assembly is formed in the mutual inductance housing in a state of being sleeved on the insulating sleeve.

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