High bandwidth current transformer
By using a segmented impedance matching design and utilizing parasitic balancing capacitors and distributed resistance components, the problem of limited bandwidth of current transformers was solved, achieving high accuracy and stability in high-frequency measurements and expanding the bandwidth of current transformers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2026-07-24
AI Technical Summary
Existing current transformers have limited bandwidth and insufficient high-frequency measurement capabilities, making it difficult to achieve high-precision and stable current frequency measurement.
By using a segmented impedance matching design, parasitic balancing capacitor banks and distributed resistor components are employed to balance parasitic inductance and parasitic capacitance, thereby achieving impedance matching of the winding inductance and expanding the bandwidth of the current transformer.
This improved the bandwidth and measurement accuracy of the current transformer, resulting in a wider frequency response range and faster signal transmission.
Smart Images
Figure CN224554149U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a current transformer for current measurement, and more particularly to a high-bandwidth current transformer. Background Technology
[0002] Current transformers have the advantage of isolated measurement, but in general, their bandwidth is limited and their high-frequency measurement capability is limited. Specifically, the bandwidth of a current transformer refers to its ability to accurately measure the frequency range of current, that is, the frequency range in which it can maintain high accuracy 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 a current transformer is that the winding wire is wound onto the magnetic core. Therefore, leakage inductance is inevitable when the current transformer is working. In addition, there is 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, which will limit the bandwidth of the current transformer and make it difficult to extend the upper frequency limit. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a high-bandwidth current transformer. Through segmented impedance matching design, parasitic inductance and parasitic capacitance are balanced and the output impedance is matched, which can effectively improve the bandwidth and measurement accuracy of the current transformer.
[0005] According to the technical solution provided by this utility model, a high-bandwidth current transformer is provided, the high-bandwidth current transformer comprising:
[0006] The current transformer body includes a current transformer housing and a winding assembly disposed within the current transformer housing, wherein...
[0007] The winding assembly includes at least a winding unit, and the winding unit includes at least a plurality of turns of winding 10, forming a corresponding winding inductance based on one or more turns of winding.
[0008] The assembly state of the winding unit in the winding assembly within the transformer housing is configured to generate a parasitic balancing capacitor bank. The parasitic balancing capacitor bank includes several parasitic balancing capacitors. The parasitic balancing capacitors in the parasitic balancing capacitor bank correspond one-to-one with the winding inductance formed by the winding unit, so as to use one parasitic balancing capacitor to balance the corresponding winding inductance.
[0009] A distributed component, assembled on a winding assembly, includes several distributed elements, wherein one distributed element is adapted to the winding of a corresponding turn within the winding unit to achieve impedance matching with the winding inductance and parasitic capacitance.
[0010] The distributed elements within the distributed component include at least distributed resistors, wherein...
[0011] When distributed elements use distributed resistors, the distributed resistors are mounted on the component carrier, and the distributed resistors are mounted on the winding assembly through the component carrier, so that the distributed resistors on the component carrier are in a wrapped state on the winding assembly, and each distributed resistor is configured to be electrically connected to the corresponding turn of the winding.
[0012] The component carrier includes at least a flexible PCB board, wherein...
[0013] When the component carrier uses a flexible PCB board, the distributed resistors are distributed on the first surface of the flexible PCB board, and a resistor pad unit corresponding to each distributed resistor is set on the second surface of the flexible PCB board. The resistor pad unit includes at least two resistor pads, and the two resistor pads are electrically connected to the end of the corresponding distributed resistor.
[0014] When a distributed resistor is electrically connected to the corresponding turn of a winding, at least the corresponding turn of the winding should be soldered 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 that are adapted to the corresponding turn of the winding are connected in series.
[0016] The component carrier plate 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 resistor string, and in the case of current inductance, the measurement accuracy adjustment unit and the current inductance load are connected in parallel.
[0018] The measurement accuracy adjustment unit includes at least one accuracy adjustment resistor, wherein...
[0019] When the measurement accuracy adjustment unit uses 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 within the winding frame, wherein...
[0021] The component carrier is assembled on the winding frame, and the winding unit is wound on the winding frame and the component carrier, with the winding unit in contact with the component carrier.
[0022] The winding frame includes a lower frame shell and an upper frame shell adapted to the lower frame shell, wherein,
[0023] The upper shell and the lower shell of the skeleton are aligned and connected, and the component carrier surrounds the aligned and connected upper shell and lower shell of the skeleton, and the component carrier at least surrounds and covers the joint between the upper shell and the lower shell of the skeleton.
[0024] The distributed resistor is located in a groove on one side surface of the component carrier near the junction of the upper shell and the lower shell of the frame.
[0025] At least one frame support positioning member is also provided on the winding frame. The winding frame is aligned and assembled in the transformer housing through the frame support positioning member to configure the assembly state of the winding unit in the transformer housing and generate the corresponding parasitic balance capacitance.
[0026] The current transformer housing includes a lower current transformer housing and an upper current transformer housing adapted to the lower current transformer housing, wherein,
[0027] A skeleton sleeve is provided inside the lower shell of the mutual inductor, and a skeleton assembly positioning component adapted to the skeleton support positioning component is provided inside the lower shell of the mutual inductor.
[0028] When assembling the winding bobbin inside the transformer housing, the winding bobbin is placed on the bobbin sleeve, and the bobbin support positioning piece and the bobbin assembly positioning piece are aligned and connected to each other, so as to align and assemble the winding bobbin inside the lower casing of the transformer, and achieve the assembly state of configuring the winding unit inside the transformer housing.
[0029] The transformer housing has a through-hole, and an insulating sleeve is provided in the through-hole. The winding assembly is fitted onto the insulating sleeve inside the transformer housing.
[0030] The advantages of this utility model are: the assembly state of the winding unit in the winding assembly within the transformer housing is configured to generate a parasitic balancing capacitor bank. The parasitic balancing capacitors in the parasitic balancing capacitor bank balance the corresponding winding inductance. When the parasitic capacitance is insufficient to achieve balance, the balance can be increased by the distributed capacitors and / or distributed resistors in the distributed assembly. The connection with the winding unit achieves impedance matching, thereby expanding the bandwidth of the current transformer and improving the current measurement accuracy. Attached Figure Description
[0031] Figure 1 This is a perspective view of one embodiment of the high-bandwidth current transformer of this utility model.
[0032] Figure 2 This is a schematic diagram of one embodiment of the present invention after removing the mutual inductance shell.
[0033] Figure 3 This is a schematic diagram of one embodiment of the mutual inductance lower shell of this utility model.
[0034] Figure 4This is a schematic diagram of one embodiment of the winding assembly and insulating sleeve of this utility model, showing their corresponding positions.
[0035] Figure 5 This is a schematic diagram of an embodiment of the distributed component and winding frame of this utility model.
[0036] Figure 6 This is a schematic diagram of an embodiment of the distributed component and the skeleton lower shell of this utility model.
[0037] Figure 7 This is a schematic diagram of one embodiment of the skeleton shell of this utility model.
[0038] Figure 8 This is a schematic diagram of one embodiment of the lower shell of the skeleton of this utility model.
[0039] Figure 9 This is a partially enlarged view of an embodiment of the present invention, showing the combination of the winding, distributed components, and frame housing.
[0040] Figure 10 This is a schematic diagram of one embodiment of the distributed component of this utility model.
[0041] Figure 11 This is the equivalent circuit diagram of the current transformer of this utility model.
[0042] Figure 12 This is a schematic diagram of an embodiment of the present invention that achieves impedance matching by cooperating with a winding inductor.
[0043] Explanation of reference numerals in the attached drawings: 1-Lower shell of mutual inductor, 2-Upper shell of mutual inductor, 3-Mutual inductor connector, 4-Hole of mutual inductor shell, 5-Winding assembly, 6-Insulating sleeve, 7-Frame sleeve, 8-Frame support positioning component, 9-Flexible PCB board, 10-Winding, 11-Frame hole, 12-Upper shell of frame, 13-Lower shell of frame, 14-Upper support positioning body, 15-Lower support positioning body, 16-Outer cylinder of lower shell of frame, 17-Inner cylinder of lower shell of frame, 18-Frame support positioning groove, 19-Resistor pad, 20-Distributed resistor, 21-Outer cylinder of lower shell of mutual inductor, 22-Hole of lower shell of mutual inductor, 23-Resistor via, 24-Frame assembly positioning groove, 25-Carrier support platform. Detailed Implementation
[0044] The present invention will be further described below with reference to the specific accompanying drawings and embodiments.
[0045] To effectively improve the bandwidth and measurement accuracy of current transformers, this invention provides a high-bandwidth current transformer, specifically, the high-bandwidth current transformer includes:
[0046] The current transformer body includes a current transformer housing and a winding assembly 5 disposed within the current transformer housing, wherein...
[0047] The winding assembly 5 includes at least a winding unit, and the winding unit includes at least a plurality of turns of winding 10, forming a corresponding winding inductance based on one or more turns of winding 10.
[0048] Configure the winding unit in the winding assembly 5 to be in the assembly state of the current transformer housing to generate a parasitic balancing capacitor group. The parasitic balancing capacitor group includes a number of parasitic balancing capacitors. The parasitic balancing capacitors in the parasitic balancing capacitor group correspond one-to-one with the winding inductance formed by the winding unit, so as to use one parasitic balancing capacitor to balance the corresponding winding inductance.
[0049] A distributed component, assembled on the winding assembly 5, includes several distributed elements, wherein one distributed element is adapted 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 a commonly used form, specifically designed to meet the requirements of current measurement through current inductance. Generally, the transformer body should at least include a transformer housing and a winding assembly 5 located within the transformer housing. That is, the winding assembly 5 can be housed within the transformer housing 1. The winding assembly 5 is a component with current inductance capability. Figure 1 An embodiment of the current transformer of this utility model is shown in the figure. Figure 2 The diagram shows an embodiment in which the winding assembly 5 is located inside the transformer housing. Generally, the transformer housing may be a metal housing.
[0051] Generally, the winding assembly 5 should include at least a winding unit, which may include a winding 10 of several turns. For example, the winding unit can be formed by winding a single winding wire. When winding to form the winding unit, a winding 10 can be formed by each turn of the corresponding winding wire. The method of forming the winding unit by winding a winding wire is consistent with the prior art and will not be elaborated here. In specific implementation, the number of windings 10 included in the winding unit can be selected according to actual needs, based on meeting 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, for transformers with relatively long windings, as the bus current frequency increases, the wavelength of the induced electromagnetic wave can be equal to or less than the winding length. Therefore, at high frequencies, the winding unit formed by the windings cannot be considered a lumped element but should be considered a distributed device. Generally, when the winding length is greater than one-quarter of the electromagnetic wave wavelength, the winding unit must be considered a distributed device.
[0053] When the winding unit is considered as a distributed device, a winding target line is formed based on one or more turns of winding 10. The winding target line formed can correspond to a winding inductance. Based on the winding line winding method to form a single winding, it can be seen that the winding inductances formed by all the winding target lines are in series. Figure 11 The figure shows an embodiment in which the winding unit includes N winding target lines. In this case, N winding inductors can be formed accordingly. In the figure, the N winding inductors are winding inductor L1, winding inductor L2, ..., winding inductor LN, and the winding inductors L1 to LN are connected in series.
[0054] As described in the background section above, after the winding assembly 5 is assembled into the transformer housing, parasitic capacitances are formed between the winding unit and the transformer housing, as well as between each turn of the winding 10 within the winding unit. It should be understood that the formed parasitic capacitances are related to the assembly state of the winding assembly 5 within the transformer housing. This assembly state includes at least the assembly position of the winding assembly 5 within the transformer housing. Therefore, after determining the winding inductance formed by the aforementioned target winding line, a parasitic balancing capacitance group can be generated by configuring the assembly state of the winding unit within the winding assembly 5 within the transformer housing. In specific implementation, the generated parasitic balancing capacitance group should be connected correspondingly to the winding inductance formed by the aforementioned target winding line within the winding unit. The corresponding connection state will be referred to below. Figure 11 Let's illustrate with examples.
[0055] Specifically, the parasitic balancing capacitor bank may include several parasitic balancing capacitors, which can be used to balance the winding inductance. Figure 11 In the diagram, capacitors Cx0, Cx1, ..., CxN are the N+1 parasitic balancing capacitors within the parasitic balancing capacitor bank. As shown in the diagram, when balancing the winding inductor, they need to be connected correspondingly to the winding inductor, such as... Figure 11 In the diagram, one end of capacitor Cx0 is connected to one end of winding inductor L1, and 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, and the other end of capacitor Cx1 is grounded. Other cases can be referenced. Figure 11And this explanation.
[0056] In one embodiment of this utility model, a distributed component is further provided on the winding assembly 5. The distributed component includes several distributed elements. The number of distributed elements in the distributed component can be selected as needed. 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 practical implementation, the distributed components are installed on winding assembly 5 and adapted to the corresponding winding 10 within the winding unit. This achieves adaptation to the corresponding winding inductance and parasitic capacitance, thus realizing impedance matching. It should be noted that in impedance matching mode, reflected waves are minimized, and the waveform quality of the incident wave is optimal, achieving the fastest signal rise or fall edges, resulting in a wider bandwidth and thus expanding the frequency band of the current transformer. The incident and reflected wave characteristics are described in the following sections.
[0058] As can be seen from the above description, this utility model balances the corresponding winding inductance by using parasitic balancing capacitors in the parasitic balancing capacitor bank, and achieves impedance matching by connecting the distributed components to the winding unit, thereby expanding the bandwidth of the current transformer.
[0059] In one embodiment of this utility model, the distributed elements within the distributed component include at least a distributed resistor 20, wherein...
[0060] When the distributed element uses a distributed resistor 20, the distributed resistor 20 is mounted on the component carrier, and the distributed resistor 20 is mounted on the winding component 5 through the component carrier, so that the distributed resistor 20 on the component carrier is in a wrapped 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 specific implementation, the distributed element can be a distributed resistor 20. Specifically, the distributed resistor 20 refers to resistors distributed on the component carrier. The distributed resistor 20 can adopt commonly used resistor types, such as high-precision resistors with low temperature coefficients, to improve the stability of the distributed resistor 20. To facilitate electrical connection with the corresponding turns of the winding 10, thereby achieving a compatible connection with the corresponding winding inductance, the distributed resistor 20 is preferably distributed along the length of the component carrier. Thus, the distributed resistor 20 can be mounted on the winding assembly 5 via the component carrier, and all the distributed resistors 20 are arranged in a ring around the winding assembly 5. Specifically, mounting the distributed resistors 20 on the winding assembly 5 means that all the distributed resistors 20 on the component carrier are mounted on the winding assembly 5.
[0062] It should be noted that when all the distributed components 20 are assembled on the winding assembly 5, all the distributed resistors 20 are in a ring-like state on the winding assembly 5, that is, the different distributed resistors 20 are distributed in different positions on the winding assembly 5, which makes it convenient to electrically connect the winding 10 of the corresponding turn to the corresponding distributed resistor 20.
[0063] It should be understood that after determining the winding inductance corresponding to the turn winding 10, the inductance value corresponding to the winding inductance and the corresponding winding line internal resistance can be determined. In addition, based on the assembly state of the winding unit in the winding assembly 5 within the transformer housing, the size of the corresponding parasitic capacitance can be determined using existing commonly used technical methods. After that, the resistance value required for impedance matching can be determined.
[0064] After determining the resistance required for impedance matching, the resistance value corresponding to a distributed resistor 20 can be determined. Specifically, the impedance matching process described above can be described by the telegraph equation, which reflects the energy distribution and propagation characteristics in the transmission line and is the basis for analyzing high-frequency signal transmission. It is a second-order partial differential equation, and its solution usually takes the form of waves, including incident waves and reflected waves. Specifically, the incident wave is an electromagnetic wave generated based on 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, reflected waves can be minimized, and a wider bandwidth can be achieved.
[0065] In one embodiment of this utility model, the component carrier includes at least a flexible PCB board 9, wherein...
[0066] When the component carrier adopts a flexible PCB board 9, the distributed resistors 20 are distributed on the first surface of the flexible PCB board 9, and a resistor pad unit corresponding to each distributed resistor 20 is provided on the second surface of the flexible PCB board 9. The resistor pad unit includes at least two resistor pads 19, and the two resistor pads 19 are electrically connected to the end of the corresponding distributed resistor 20 respectively.
[0067] When the distributed resistor 20 is electrically connected to the winding 10 of the corresponding turn, at least the winding 10 of the corresponding turn shall be soldered to the resistance pad 19 of the corresponding distributed resistor 20.
[0068] To facilitate assembly onto the winding assembly 5, the assembly carrier can preferably be a flexible PCB board 9. The flexible PCB board 9 can adopt a commonly used form, and by utilizing its flexibility, it can be configured in a ring shape. Figure 10The figure shows an embodiment where the flexible PCB board 9 is configured in a ring shape. In this case, multiple distributed resistors 20 are located on the inner surface of the flexible PCB board 9, while the resistor pad units are located on the outer surface of the flexible PCB board 9. That is, the inner surface of the flexible PCB board 9 serves as the first surface, and the outer surface of the flexible PCB board 9 serves as the second surface. In specific implementation, when the component carrier uses the flexible PCB board 9, the flexible PCB board 9 can be configured in an arc shape first, and then the distributed resistors 20 can be assembled on the winding assembly 5 in a surrounding manner through the flexible PCB board 9.
[0069] Figure 4 The figure shows an embodiment in which a flexible PCB board 9 is mounted on a winding assembly 5. As can be seen from the figure, when the flexible PCB board 9 is mounted on the winding assembly 5, the second surface of the flexible PCB board 9 is exposed, that is, the resistor pad unit is exposed, so that the distributed resistor 20 is electrically connected to the winding 10 of the corresponding turn through the resistor pad unit.
[0070] In practical 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. Since 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 the lead wires from both ends of the distributed resistor 20 can pass through the resistor via 23 to make electrical connection with the corresponding resistor pad 19.
[0071] In one embodiment of this utility model, when the distributed resistor 20 is electrically connected to the winding 10 of the corresponding turn, it specifically means that the winding 10 of the corresponding turn is soldered to the resistance pad 19 of the corresponding distributed resistor 20. Figure 9 The diagram illustrates one embodiment of soldering winding 10 to corresponding resistor pads 19. In practice, after each distributed resistor is electrically connected to the corresponding turn of the winding, the multiple distributed resistors 20 adapted to the corresponding turn winding are connected in series. Figure 11 The diagram illustrates one embodiment in which multiple distributed resistors 20 are connected in series, by Figure 11 As can be seen from the figure, one embodiment of the distributed component includes N distributed resistors 20, that is, the number of distributed resistors 20 is consistent with the number of winding inductors. In this case, there is a one-to-one correspondence between the distributed resistors 20 and the winding inductors.
[0072] Figure 11In the diagram, N distributed resistors 20 are resistors Rx1, Rx2, ..., RxN. One end of resistor Rx1 is connected to one end of winding inductor L1 and one end of capacitor Cx0. The other end of resistor Rx1 is connected to one end of resistor Rx2, the other end of winding inductor L1, one end of winding inductor L2, and one end of capacitor Cx1. The multiple distributed resistors 20 form a series connection, and the corresponding connections with the winding inductors can be found in [reference needed]. Figure 11 And this explanation.
[0073] As explained above, the number of distributed resistors 20 can differ from the number of winding inductors. If 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 associated with winding inductors L1 and 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 inductors L2 and L3. In specific implementation, based on the above description of forming winding inductors, the corresponding turns of inductor can be soldered to the corresponding resistor pads 19 of the distributed resistor 20. That is, this invention is specifically designed to meet impedance matching requirements, which will not be elaborated further here.
[0074] Furthermore, the distributed elements within the distributed assembly may also include distributed capacitors. When the parasitic capacitance between the winding wire and the casing is insufficient to achieve balance compensation, an equivalent capacitance can be added through the distributed capacitors within the distributed assembly to achieve better balance compensation. In specific implementations, the distributed capacitors should be connected in parallel with the corresponding parasitic capacitances.
[0075] As described above, this invention allows all matching components to be mounted on the flexible PCB board 9, including surface-mount distributed resistors and / or distributed capacitors. The distributed resistors can be low-temperature coefficient resistors, which, compared to copper, significantly reduce the temperature coefficient, resulting in better temperature stability and accuracy drift. The distributed capacitors can be miniaturized and provide higher capacitance values.
[0076] Figure 12 For this utility model, a section of the winding can correspond to one winding inductance. The winding inductance, combined capacitance, and distributed resistance achieve impedance matching in this embodiment. Specifically, based on the telegraph equations, we have:
[0077]
[0078] Where U is the terminal voltage at terminals AB or CD, I is the impedance current between terminals AC, γ is the transmission coefficient, and d 2 U is the second derivative of the terminal voltage, d 2 I is the second derivative of the impedance current, d 2z is the second derivative of the length.
[0079] For the transmission coefficient γ, we have:
[0080]
[0081] Where ω is the signal frequency, L AC Rs is the inductance value of the winding, C is the resistance of the wire forming the winding inductance, and C is the resistance of the wire forming the winding inductance. t R is the inter-turn capacitance between the windings. R For distributed resistance, C P For a combined capacitor, generally, the combined capacitor C P This includes parasitic capacitance and / or distributed capacitance.
[0082] When the above winding inductance is Figure 11 When L1 is in the range, the distributed resistance R R Should be Figure 11 Rx1 in the figure, combined capacitor C P At least for Figure 11 For Cx1 in the above example, when the winding inductance is otherwise specified, please refer to [the relevant documentation / reference]. Figure 11 And this section explains how to determine the corresponding distributed resistance R. R and combined capacitor C P The situation regarding internal parasitic capacitance will not be illustrated with examples here.
[0083] Based on the above telegraph equations, the corresponding characteristic impedance can be obtained as follows:
[0084]
[0085] When the wire resistance Rs is small, the distributed resistance R R Larger and When the characteristic impedance Z0 mentioned above is found to be:
[0086] If the current transformer load RL is an oscilloscope, the commonly used value for the current transformer load RL is 50Ω or 1MΩ. Specifically, in the 1MΩ range, it often also includes a certain amount of capacitance. Generally, the equivalent capacitance is in parallel, and the capacitance value is on the order of pF. It should be noted that the impedance matching state, that is, the characteristic impedance Z0 and the current transformer load RL are in a complex conjugate state.
[0087] As can be seen from the above explanation, when the inductance value L of the winding inductance is determined... AC Subsequently, when impedance matching is required, the corresponding parasitic capacitance can be determined by means of technical means in this field, based on the type of current transformer load RL. Then, the required capacitance value of the distributed capacitance can be determined until impedance matching is achieved.
[0088] It should be noted that the high-frequency characteristics of current transformers require a high number of matching segments, resulting in a large number of matching resistors and capacitors, and demanding high component precision. Using multiple discrete components would significantly increase the workload of assembly and adjustment. This invention integrates a large number of distributed resistors and / or distributed capacitors onto a flexible PCB board 9, utilizing a mature process that allows for efficient mass production. By assembling distributed resistors and capacitors on the flexible PCB board 9, the number of matching components is greatly reduced, simplifying processing, assembly, and debugging, thus improving production efficiency.
[0089] In one embodiment of this utility model, the component carrier plate is further provided with a measurement accuracy adjustment unit for adjusting the output accuracy, wherein...
[0090] The measurement accuracy adjustment unit is connected to one end of the distributed resistor string, and in the case of current inductance, the measurement accuracy adjustment unit and the current inductance load are connected in parallel. To adjust the accuracy of the current measurement, a measurement accuracy adjustment unit is also provided on the component carrier board. When the component carrier board uses a flexible PCB board 9, the measurement accuracy adjustment unit and the distributed resistors 20 are simultaneously located on the flexible PCB board 9. The distributed resistor string specifically refers to the series connection of multiple distributed resistors 20, such as... Figure 11 In the embodiment shown, resistors Rx1, Rx2, ..., RxN can be connected in series to form a distributed resistor string.
[0091] In specific implementation, the measurement accuracy adjustment unit includes at least one accuracy adjustment resistor, wherein,
[0092] When the measurement accuracy adjustment unit uses 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 The figure illustrates an embodiment where the measurement accuracy adjustment unit uses an accuracy adjustment resistor. In the figure, Rp is the accuracy adjustment resistor, one end of which is connected to one end of resistor Rx1, and the other end of the accuracy adjustment resistor is grounded. Of course, when the accuracy adjustment resistor is connected to resistor Rx1, it is also adapted to be connected to winding inductor L1 and capacitor Cx0. Figure 11 In this context, RL represents the current transformer load, and the output terminal of the current transformer is connected to the current transformer load RL.
[0094] When performing current inductance, since the precision adjustment resistor Rp is connected in series and parallel with the distributed resistor, the shunt ratio of the current flowing to the current inductance load RL can be changed by adjusting the resistance value of the precision adjustment resistor Rp, thereby improving the precision of the current inductance.
[0095] In one embodiment of this utility model, the winding assembly 5 further includes a winding frame and a winding core assembled within the winding frame, wherein...
[0096] The component carrier is assembled on the winding frame, and the winding unit is wound on the winding frame and the component carrier, with the winding unit in contact with the component carrier.
[0097] Figure 2 and Figure 4 The figure illustrates one embodiment of the winding assembly 5. As shown, the winding assembly 5 should include a winding frame, a winding core, and winding units. The winding core is located within the winding frame, and the winding units are wound with winding wire on the winding frame. The form in which the winding core, winding frame, and winding units form the winding assembly 5 can be consistent with the prior art, as long as it can meet the mutual inductance operation required for current measurement through the winding assembly 5. It should be noted that the case where the winding core is within the winding frame is not shown in the figure. The case of the winding core can be determined in conjunction with the following description of the winding frame, specifically based on its ability to be assembled within the winding frame and form the required winding assembly 5.
[0098] As explained above, the component carrier can be a flexible PCB board 9. When the component carrier uses a flexible PCB board 9, the flexible PCB board 9 can be first wrapped around the winding frame, such as... Figure 5 As shown, the winding wire is then wound onto the winding frame. While the winding wire is wound onto the winding frame, it also wraps around the flexible PCB board 9, and the winding unit formed by the winding wire also contacts the flexible PCB board 9. Of course, the winding unit also contacts the winding frame, as shown... Figure 4 and Figure 9 As shown.
[0099] In one embodiment of this utility model, the winding frame includes a lower frame shell 13 and an upper frame shell 12 adapted to the lower frame shell 13, wherein...
[0100] The upper shell 12 and the lower shell 13 of the skeleton are aligned and connected. The component carrier surrounds the aligned and connected upper shell 12 and lower shell 13 of the skeleton, and the component carrier at least surrounds and covers the joint between the upper shell 12 and the lower shell 13 of the skeleton.
[0101] The distributed resistor 20 is located on one side surface of the component carrier near the junction of the upper shell 12 and the lower shell 13 of the frame.
[0102] Figure 4 and Figure 5The diagram illustrates one embodiment of a winding frame. As shown, the winding frame is formed by the cooperation of a lower frame shell 13 and an upper frame shell 12. The winding frame is annular in shape, with a frame hole 11 in its central region, which extends through the winding frame. When the winding unit is wound on the winding frame, the winding wire passes through the frame hole 11 and winds along the circumference of the winding frame. For an example of a winding unit wound on the winding frame, please refer to [reference needed]. Figure 2 and Figure 4 As shown, the method of winding the winding wires onto the winding frame to form a winding unit is consistent with existing technology and will not be elaborated here.
[0103] The winding bobbin is generally made of insulating material; that is, both the lower shell 13 and the upper shell 12 of the bobbin are generally made of insulating material. In order to form... Figure 2 and Figure 3 As can be seen from the above description, the winding assembly 5 in the middle first aligns and connects the upper shell 12 and the lower shell 13 of the skeleton, and then the component carrier using the flexible PCB board 9 is wrapped around the aligned and connected upper shell 12 and lower shell 13 of the skeleton, and the flexible PCB board 9 at least surrounds and covers the joint between the upper shell 12 and the lower shell 13 of the skeleton.
[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 upper shell 12 and the lower shell 13 of the skeleton, 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 the state of being exposed on the outer surface.
[0105] Figure 8 The figure shows one embodiment of the lower shell 13 of the skeleton. As can be seen from the figure, the lower shell 13 of the skeleton is also annular. The lower shell 13 of the skeleton includes an inner cylinder 17 located in the inner circle and an outer cylinder 16 located in the outer circle. The outer cylinder 16 of the skeleton surrounds the inner cylinder 17 of the skeleton. Generally, the outer cylinder 16 of the skeleton and the inner cylinder 17 of the skeleton are concentrically distributed. The inner cylinder 17 of the skeleton is hollow, while one end of the outer cylinder 16 of the skeleton is open. Figure 8 In the middle, a carrier support platform 25 is provided on the outer wall of the lower shell outer cylinder 16. The carrier support platform 25 can support the flexible PCB board 9, such as... Figure 6 As shown. Figure 6 In the middle, the flexible PCB board 9 is in the shape of a ring and is supported on the carrier support platform 25. At this time, the flexible PCB board 9 surrounds the outer cylinder 16 of the lower shell of the skeleton.
[0106] Figure 7The figure shows one embodiment of the upper skeleton shell 12. As can be seen from the figure, the shape of the upper skeleton shell 12 should be adapted to the lower skeleton shell 13 so that the upper skeleton shell 12 can be aligned and pressed onto the lower skeleton shell 13. Specifically, when the upper skeleton shell 12 is aligned and pressed onto the lower skeleton shell 13, the upper skeleton shell 12 can at least fit over the opening of the outer sleeve 16 of the lower skeleton shell. The flexible PCB board 9 is generally placed between the carrier support platform 25 and the upper skeleton shell 12. Figure 5 As shown, the joint between the upper skeleton shell 12 and the lower skeleton shell 13 includes at least the area where the upper skeleton shell 12 is fitted onto the opening of the outer sleeve 16 of the lower skeleton shell.
[0107] In practice, when the winding core is placed inside the winding frame, the winding core can be assembled into the lower shell 13 of the frame through the inner cylinder 17 of the lower shell. When the upper shell 12 of the frame is aligned and pressed onto the lower shell 13 of the frame, the winding core can be sealed inside the winding frame.
[0108] In one embodiment of this utility model, at least one skeleton support positioning member 8 is further provided on the winding skeleton. 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 the corresponding parasitic balance capacitance.
[0109] As explained above, in order to generate the required parasitic balancing capacitance, the assembly state of the winding unit within the transformer housing can be configured. The assembly state of the winding unit within the transformer housing can be referred to the above description. To ensure the accuracy and stability of the winding unit's assembly state within the transformer housing, a frame support positioning component can be provided on the winding frame. This frame support positioning component can be used to align and assemble the winding unit within the transformer housing. The following section will further explain... Figure 5 , Figure 6 , Figure 7 and Figure 8 An example is given to illustrate the use of the skeleton support and positioning component of this utility model.
[0110] like Figures 5-8 It can be seen that three skeleton support positioning parts 8 are provided on the skeleton winding. The three skeleton support positioning parts 8 are evenly distributed. Specifically, each skeleton support positioning part 8 may include an upper support positioning body 14 and a lower support positioning body 15. The upper support positioning body 14 is provided on the upper shell 12 of the skeleton, and the lower support positioning body 15 is provided on the lower shell 13 of the skeleton. The upper support positioning body 14 may be L-shaped. The first part of the upper support positioning body 14 is located on the end face of the upper shell 12 of the skeleton, and the second part of the upper support positioning body 14 is located in the skeleton upper shell hole of the upper shell 12. The skeleton upper shell hole penetrates the upper shell 12 of the skeleton.
[0111] In specific implementation, the shape of the lower support positioning body 15 can be consistent with that of 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 13 of the skeleton.
[0112] To facilitate the alignment and connection between the upper shell 12 and the lower shell 13 of the skeleton, a skeleton support positioning groove 18 can be provided on the upper end face of the inner cylinder 17 of the lower shell. The skeleton support positioning groove 18 allows for 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 upper shell 12 and the lower shell 13 of the skeleton can be achieved. Furthermore, 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 corresponds directly to the first part of the lower support positioning body 15, such as... 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 protrude from the corresponding surfaces of the winding skeleton.
[0113] In one embodiment of this utility model, the transformer housing includes a lower transformer housing 1 and an upper transformer housing 2 adapted to the lower transformer housing 1, wherein...
[0114] A skeleton sleeve 7 is provided inside the lower shell 1 of the mutual inductance, and a skeleton assembly positioning component adapted to the skeleton support positioning component 8 is provided inside the lower shell 2 of the mutual inductance.
[0115] When assembling the winding bobbin inside the transformer housing, the winding bobbin is placed on the bobbin sleeve 7, and the bobbin support positioning piece 8 and the bobbin assembly positioning piece are aligned and connected to each other, so as to align and assemble the winding bobbin inside the lower casing of the transformer, and achieve the assembly state of configuring the winding unit inside the transformer housing.
[0116] Figure 1 The figure illustrates one embodiment of a current transformer housing. As shown in the figure, the current transformer housing is annular or near-annular in shape. Of course, the shape of the current transformer housing should not affect the installation of the winding assembly 5 inside the current transformer housing. In a specific implementation, the current transformer housing may include a lower current transformer housing 1 and an upper current transformer housing 2. The upper current transformer housing 2 can be aligned and connected with the lower current transformer housing 1. That is, when the upper current transformer housing 2 and the lower current transformer housing 1 are aligned and connected, the current transformer housing is formed.
[0117] Figure 2 and Figure 3The figure shows one embodiment of the mutual inductance lower shell 1. As can be seen from the figure, the shape of the mutual inductance lower shell 1 can be similar to the shape of the skeleton lower shell 13 described above. 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. One end of the skeleton sleeve 7 is connected to the end plate of the mutual inductance lower shell outer cylinder 21. Figure 3 As shown.
[0118] In order to be compatible with the frame support positioning component 8, a frame assembly positioning component can be provided inside the mutual inductance lower shell 1. When the frame support positioning component 8 adopts the above-described form... Figure 3 The figure shows an embodiment of the skeleton assembly positioning component. In the figure, the skeleton assembly positioning component 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 lower shell of the mutual inductor. 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 component 8 and the skeleton assembly positioning component can be aligned and connected to each other. This enables the winding skeleton to be aligned and assembled in the lower shell of the mutual inductor, and achieves the assembly state of configuring the winding unit in the transformer housing.
[0119] Figure 2 In this process, the winding bobbin should be fitted onto the bobbin sleeve 7, and the second part of the upper support positioning body 14 and the first part of the lower support 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 assembled into the lower transformer housing 1 first. When assembling the winding bobbin into the lower transformer housing 1, the winding bobbin can be fitted onto the bobbin sleeve 7, and then the first part of the upper support positioning body 15 can be embedded in the bobbin assembly positioning groove 24. At this time, the assembly of the winding bobbin into the lower transformer housing 1 is completed.
[0120] In one embodiment of this utility model, a current transformer housing hole 4 is provided inside the current transformer housing, and an insulating sleeve 6 is provided inside the current transformer housing hole 4, and the winding assembly is formed inside the current transformer housing and 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. The transformer housing hole 4 penetrates the transformer housing so that it can be fitted onto the busbar of the current to be measured. In specific implementation, the transformer housing hole 4 can correspond to the through hole of the skeleton sleeve 7.
[0122] Figure 1An insulating sleeve 6 is also installed inside the hole 4 of the transformer housing. The size of the insulating sleeve 6 is adapted to the transformer housing 4. After the insulating sleeve 6 is located inside the hole 4 of the transformer housing, it can contact the inner wall of the frame sleeve 7. The insulating sleeve 6 can prevent the lower transformer housing 1 and the upper transformer housing 2 from forming a current path around the iron core, thus avoiding the occurrence of short-circuit turns. The lower transformer housing 1 and the upper transformer housing 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 slit at the insulating sleeve 6, and the metal on both sides of the insulating sleeve 6 is interlaced, making it difficult for external electromagnetic interference to penetrate, thus achieving a good shielding effect. Specifically, the metal on both sides of the insulating sleeve 6 refers to the part of the frame sleeve 7 and the upper transformer housing 2 embedded in the insulating sleeve 6.
[0123] Figure 1 In the middle, a mutual inductance connector 3 is also provided on the lower shell 1 of the mutual inductance. The wire ends of the winding wires that are wound to form the winding unit can be led out through the mutual inductance connector 3 so as to connect with the external circuit. The specific connection with the external circuit can be consistent with the existing technology, so as to meet the requirements of current mutual inductance measurement.
Claims
1. A high-bandwidth current transformer, characterized in that, The high-bandwidth current transformer includes: The current transformer body includes a current transformer housing and a winding assembly disposed within the current transformer housing, wherein... The winding assembly includes at least a winding unit, and the winding unit includes at least a number of turns of winding, forming a corresponding winding inductance based on one or more turns of winding; The assembly state of the winding unit in the winding assembly within the transformer housing is configured to generate a parasitic balancing capacitor bank. The parasitic balancing capacitor bank includes several parasitic balancing capacitors. The parasitic balancing capacitors in the parasitic balancing capacitor bank correspond one-to-one with the winding inductance formed by the winding unit, so as to use one parasitic balancing capacitor to balance the corresponding winding inductance. A distributed component, assembled on a winding assembly, includes several distributed elements, wherein one distributed element is adapted to the winding of a corresponding turn within 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 within the distributed component include at least distributed resistors, wherein... When distributed elements use distributed resistors, the distributed resistors are mounted on the component carrier, and the distributed resistors are mounted on the winding assembly through the component carrier, so that the distributed resistors on the component carrier are in a wrapped state on the winding assembly, 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 includes at least a flexible PCB board, wherein... When the component carrier uses a flexible PCB board, the distributed resistors are distributed on the first surface of the flexible PCB board, and a resistor pad unit corresponding to each distributed resistor is set on the second surface of the flexible PCB board. The resistor pad unit includes at least two resistor pads, and the two resistor pads are electrically connected to the end of the corresponding distributed resistor. When a distributed resistor is electrically connected to the corresponding turn of a winding, at least the corresponding turn of the winding should be soldered to the resistance pad of the corresponding distributed resistor.
4. The high-bandwidth current transformer according to claim 2, characterized in that: each After the distributed resistor is electrically connected to the corresponding turn of the winding, the multiple distributed resistors that are adapted to the corresponding turn of the winding are connected in series. The component carrier plate 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 resistor string, and in the case of current inductance, the measurement accuracy adjustment unit and the current inductance load are connected 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 uses 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 within the winding frame, wherein... The component carrier is assembled on the winding frame, and the winding unit is wound on the winding frame and the component carrier, with the winding unit in contact with the component carrier.
7. The high-bandwidth current transformer according to claim 6, characterized in that: The winding frame includes a lower frame shell and an upper frame shell adapted to the lower frame shell, wherein, The upper shell and the lower shell of the skeleton are aligned and connected, and the component carrier surrounds the aligned and connected upper shell and lower shell of the skeleton, and the component carrier at least surrounds and covers the joint between the upper shell and the lower shell of the skeleton. The distributed resistor is located in a groove on one side surface of the component carrier near the junction of the upper shell and the lower shell of the frame.
8. The high-bandwidth current transformer according to claim 7, characterized in that: in The winding frame is also provided with at least one frame support positioning member. The winding frame is aligned and assembled in the transformer housing through the frame support positioning member to configure the assembly state of the winding unit in the transformer housing and generate the corresponding parasitic balance capacitance.
9. The high-bandwidth current transformer according to claim 8, characterized in that: The current transformer housing includes a lower current transformer housing and an upper current transformer housing adapted to the lower current transformer housing, wherein, A skeleton sleeve is provided inside the lower shell of the mutual inductor, and a skeleton assembly positioning component adapted to the skeleton support positioning component is provided inside the lower shell of the mutual inductor. When assembling the winding bobbin inside the transformer housing, the winding bobbin is placed on the bobbin sleeve, and the bobbin support positioning piece and the bobbin assembly positioning piece are aligned and connected to each other, so as to align and assemble the winding bobbin inside the lower casing of the transformer, and achieve the assembly state of configuring the winding unit inside the transformer housing.
10. The high-bandwidth current transformer according to any one of claims 1 to 5, characterized in that: The transformer housing has a through-hole, and an insulating sleeve is provided in the through-hole. The winding assembly is fitted onto the insulating sleeve inside the transformer housing.