WO2018099153A1 - 电流互感器 - Google Patents
电流互感器 Download PDFInfo
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- WO2018099153A1 WO2018099153A1 PCT/CN2017/100140 CN2017100140W WO2018099153A1 WO 2018099153 A1 WO2018099153 A1 WO 2018099153A1 CN 2017100140 W CN2017100140 W CN 2017100140W WO 2018099153 A1 WO2018099153 A1 WO 2018099153A1
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- shaped yoke
- current transformer
- sensing head
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/38—Instruments transformers for polyphase ac
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/2823—Wires
- H01F27/2828—Construction of conductive connections, of leads
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/30—Fastening or clamping coils, windings, or parts thereof together; Fastening or mounting coils or windings on core, casing, or other support
- H01F27/306—Fastening or mounting coils or windings on core, casing or other support
Definitions
- the invention relates to a current transformer, which is mainly used for current measurement in the smart meter industry.
- the current measurement circuit of the smart energy meter industry usually uses a manganese copper shunt and an electromagnetic current transformer.
- the manganese-copper shunt current sensor is low in cost, and its working principle is resistance partial pressure. Since the resistance of manganese-copper has little change with temperature, the dispersion is relatively large, so it is widely used in the single-phase electric energy meter of 2.0 class. .
- the resistance of the sampling resistor is between 250 and 500 ⁇ , and the calorific value is about 1 to 2 W.
- the advantages of the manganese-copper shunt are: simple processing, low cost, and measurement of both DC component and higher harmonics.
- the frequency characteristics can be stably transmitted from the DC-1MHz signal (limited by the sampling rate of the metering loop, and the actual use range is usually below 25kHz).
- the disadvantages of the manganese-copper shunt are: 1.
- the heat generated by the resistor is large at high current. If the screw is not firmly crimped when the terminal is assembled, or the heat treatment is improper, it is easy to burn the meter. 2.
- the resistance value is discrete, and although the resistance value changes little with temperature, it is subject to irregular temperature changes. Therefore, it is not suitable for high-precision measurement.
- the electric energy meter using the manganese-copper shunt the fire line L is used as the reference “ground” of the metering circuit (the gauge chip withstand voltage is generally below 5V, if the voltage divider is input using the fire line L, and With the zero line N as the ground line, the differential pressure of the two analog inputs of the metering chip will reach 220VAC, the chip can not withstand), the manganese copper shunt is "hard-connected" with the fire line.
- the current transformer is composed of a closed core and a winding, and its primary winding has few turns, and the string is in the line of the current to be measured. Therefore, it often has all the current flowing through the line, and the number of turns in the secondary winding is relatively large, and is connected in series in the measuring instrument and the protection circuit.
- the current transformer When the current transformer is working, its secondary circuit is always closed, so the measuring instrument and The impedance of the series circuit of the protection circuit is small, and the working state of the current transformer is close to a short circuit.
- the advantages of the transformer are good linearity, high stability, and almost no accuracy with temperature, especially suitable for higher accuracy (0.5S class) measurement.
- the reference end of the current sampling of the energy meter using the current transformer is connected to the neutral line on the secondary side, so the primary side current input is isolated from the voltage loop (see Figure 3), so the reference end of the metering chip can be zero.
- Line N such that the voltage difference between the multiple analog inputs of the metering chip will be controlled below 2V, within the allowable range of the operating voltage of the chip typically below 5V.
- the voltage and current isolation access method is especially suitable for applications requiring more than two current loop measurements, such as two-phase meters, three-phase three-wire meters, and three-phase four-wire meters.
- the disadvantages of the transformer are: large volume, high cost, and weak anti-overload capability.
- the frequency range of the measurable signal generally does not exceed 2.5 kHz, especially the secondary side current measurement loop cannot open, otherwise it will generate extremely high voltage and damage measurement. Circuit!
- the object of the present invention is to overcome the above problems and to provide a current transformer which has the low-cost characteristics of a manganese-copper shunt and the separation of a current loop and a voltage loop similar to a transformer, which is advantageous for greatly reducing the three-phase.
- the size and weight of smart meters reduce costs.
- a current transformer comprising a sensing head, a baffle and a C-shaped yoke, wherein
- the sensing head has an output terminal connected to the current sampling circuit
- baffle passing through the C-shaped yoke, the two ends of which are respectively connected to the incoming end of the live wire and the outgoing end of the live wire for generating an alternating magnetic field between the two ends of the C-shaped yoke after being energized;
- the sensing head is inserted through the open end of the C-shaped yoke, so that the C-shaped yoke completely covers the sensing head, and the electromotive force is induced at the output end of the sensing head by using the alternating magnetic field .
- the flow guiding strip passes through a cavity surrounded by a C-shaped yoke and a C-shaped insulating sheet.
- the sensing head is a hollow solenoid formed by uniformly winding a wire, and the hollow solenoid is connected at both ends to the current sampling circuit.
- the hollow solenoid has an inner diameter of 0.5-1.5 mm and a winding number of 1-10 ⁇ .
- the hollow solenoid is fixedly embedded on the PCB board where the current sampling circuit is located.
- the sensing head is a planar spiral or planar polygonal spiral PCB type air-core coil directly printed on a PCB board on which the current sampling circuit is located.
- the PCB type air core coil has a number of turns of 3 inches, an inner diameter of 0.5-2 mm, and an outer diameter of 4.5 mm.
- the flow guide bar comprises a U-shaped inlet end connection section, an induction section and an outlet end connection section; wherein the inlet end connection section is connected to the live line inlet end, and the outlet end connection section is connected to the live line outlet end, and the induction section is worn.
- the C-shaped yoke is disposed such that the C-shaped yoke covers at least a portion of the sensing segment to form an arrangement state in which the flow guiding strip and the C-shaped yoke are hooked to each other.
- the C-shaped yoke is made of a Pomerol, a microcrystalline alloy or a silicon steel sheet.
- the C-shaped yoke is integrally formed by using Pomo alloy, or is formed by laminating microcrystalline alloy or Pomo alloy, or laminated with silicon steel sheets.
- the present invention has the following advantages and effects:
- the invention adopts a simpler and smaller sensing head instead of the core and the winding, which reduces the consumption of the precious metal material (copper), reduces the weight and reduces the volume. 2. It is easy to realize the primary side electrical separation of the voltage and current loops in the multiphase AC measurement, which simplifies the power supply design of the sampling circuit. 3.
- the sensing head is fixed on the PCB board (hollow solenoid) in an embedded manner, or directly printed on the PCB board (planar spiral or planar polygonal spiral coil), so that the transformer can be occupied only It is built into the inside of the energy meter with a small internal space, which greatly reduces the overall volume of the energy meter. 4.
- the present invention Since there is no iron core, the present invention has no hysteresis effect and magnetic saturation phenomenon, and the bandwidth is significantly improved. 5. There is no electrical connection between the sensor head and the current to be measured, and the impact on the circuit under test is minimal. 6. The dynamic range is wider, which can solve the electric energy measurement problem of impact load such as electrified railway and large induction cooker. 7, low cost.
- Figure 1 is a schematic illustration of an electric metering circuit employing a manganese copper shunt in the background art of the present invention.
- Figure 2 is a block diagram of a current transformer in the background art of the present invention.
- FIG. 3 is a schematic diagram of an electric metering circuit using a current transformer in the background art of the present invention.
- Embodiment 4 is a schematic view of a sensor head in Embodiment 1.
- FIG. 5 is a schematic structural view of the sensing head of FIG. 4 embedded and fixed on a PCB board.
- Fig. 6 is a front elevational view showing the transformer of the first embodiment.
- Figure 7-1 is a structural view of a monolithic Pomo C-shaped yoke.
- Fig. 7-2 is a structural view of a laminated molybdenum alloy or a microcrystalline alloy C-shaped yoke.
- Fig. 7-3 is a structural view of a C-shaped yoke of a laminated silicon steel sheet.
- Figure 8 is a schematic diagram of an electric metering circuit using the transformer of the present invention.
- Figure 9 is a schematic view showing the structure of the first embodiment applied to three current loop measurements.
- Figure 10 is an exploded view of Figure 9.
- Figure 11 is a schematic illustration of the sensing head of the second embodiment.
- Figure 12 is a schematic illustration of the sensing head of Embodiment 3.
- Figure 13 is a schematic illustration of the sensing head of the fourth embodiment.
- Figure 14 is a schematic illustration of a sensing head in the fifth embodiment.
- the current transformer of the embodiment includes a sensing head 1, a baffle 2, and a C-shaped yoke 3, wherein
- the sensing head 1 is a hollow solenoid formed by uniformly winding a wire, and an output end thereof is connected to a current sampling circuit;
- the guide bar 2 includes a serially connected inlet end connection section 2-1, an induction section 2-2, and an outlet end connection section 2-3; wherein the inlet end connection section 2-1 is connected to the live line inlet end, and the outlet end is connected.
- the segment 2-3 is connected to the live wire outlet end, and the sensing segment 2-2 passes through the C-shaped yoke 3 and is correspondingly arranged on the side of the sensing head 1 for the upper and lower planes at the open end of the C-shaped yoke 3 after being energized.
- An alternating magnetic field that is linear with current intensity
- the sensing head 1 is inserted through the open end of the C-shaped yoke 3, so that the C-shaped yoke 3 completely covers the sensing head 1, and the alternating magnetic field is used in the sensing head 1
- the output induces an electromotive force (specifically, the dipole generates a varying magnetic field after energization, thereby inducing a voltage signal proportional to the current ratio in the sensing head
- the line between the two end portions (open end) of the C-shaped yoke 3 (the shortest line between the upper and lower planes of the open end of the C-shaped yoke) is parallel to the axis of the hollow solenoid,
- the surface of the sensing head 1 is magnetically diffused outwardly, on the other hand, the external magnetic field is prevented from interfering with the measuring circuit, and the measurement accuracy is improved; in order to minimize the external magnetic field interference, the C-shaped yoke 3 is covered on the sensing head 1.
- the effective structure size must be 10mmx10mm or more.
- the C-shaped insulating sheet 4 having the same opening direction is inserted into the open end of the C-shaped yoke 3, and the sensing head 1 is inserted into the C shape.
- the open end of the insulating sheet 4 is such that the C-shaped yoke 3 and the C-shaped insulating sheet 4 completely cover the sensing head 1; the flow guiding strip 2 is surrounded by the C-shaped yoke 3 and the C-shaped insulating sheet 4 Pass through (located at the bottom of the C-shaped groove).
- the solenoid is fixedly embedded on the PCB board 5 where the current sampling circuit is located; as shown in FIG. 5, specifically, a slot is formed on the PCB board 5, and the solenoid is placed on the PCB. In the slot, the two outputs are soldered to the PCB 5 and connected to a current sampling circuit on the PCB.
- rated current In 1A, maximum Measuring current 2A ⁇ 6A
- winding turns of 1-10 ⁇ depending on the thickness of the PCB 5 (the height of the solenoid is less than or equal to the thickness of the PCB) and the signal input range of the measuring end.
- the hollow solenoid should be wound with an enameled wire, and the wire on the PCB 5 needs to be covered with insulating green oil.
- the incoming end connecting section 2-1, the sensing section 2-2, and the outgoing end connecting section 2-3 are sequentially connected in a U shape, wherein the sensing section 2-2 passes through the C-shaped yoke 3, so that The C-shaped yoke 3 covers at least a part of the sensing section 2-2, and forms an arrangement state in which the flow guiding strip 2 and the C-shaped yoke 3 are hooked to each other.
- the material of the C-type yoke 3 can be selected according to the difference of measurement accuracy, and the molybdenum, the microcrystal Alloy, or silicon steel sheet.
- three types of C-shaped yokes are provided, one is made of monolithic molybdenum alloy, as shown in FIG. 7-1, and is suitable for direct measurement of a large current with a current between 5 and 200 A.
- the voltage and current synchronous A/D sampling mode is adopted, and the period converted by the measured frequency of the voltage signal is used as the integration period of the hollow solenoid, and then the digital integration is performed by the MCU or the DSP.
- the embodiment is basically the same as the first embodiment.
- the difference is that the sensor head 1 is a planar quadrilateral spiral PCB type air-core coil directly printed on the PCB board 5 on which the current sampling circuit is located.
- the number of turns is 3 inches, the inner diameter din is 2 mm, and the outer diameter dout is 4.5 mm.
- the embodiment is basically the same as the first embodiment, except that the sensing head 1 is a planar hexagonal spiral PCB type air-core coil directly printed on the PCB board 5 on which the current sampling circuit is located.
- the number of turns is 3 ⁇ , the inner diameter din is 2 mm, and the outer diameter dout is 4.5 mm.
- the embodiment is basically the same as the first embodiment, except that the sensor head 1 is a planar octagonal spiral PCB type air-core coil directly printed on the PCB board 5 on which the current sampling circuit is located.
- the number of turns is 3 ⁇ , the inner diameter din is 2 mm, and the outer diameter dout is 4.5 mm.
- this embodiment is basically the same as Embodiment 1, except that the sensing head 1 is The planar spiral PCB type air-core coil directly printed on the PCB board 5 on which the current sampling circuit is located has a number of turns of 3 turns, an inner diameter din of 2 mm, and an outer diameter dout of 4.5 mm.
- This embodiment is basically the same as Embodiment 2 except that the inner diameter din of the sensor head 1 is 1.5 mm and the outer diameter dout is 4.5 mm.
- This embodiment is basically the same as the third embodiment except that the inner diameter din of the sensor head 1 is 1 mm and the outer diameter dout is 4.5 mm.
- This embodiment is basically the same as Embodiment 4 except that the inner diameter din of the sensor head 1 is 0.6 mm and the outer diameter dout is 4.5 mm.
- This embodiment is basically the same as the embodiment 5 except that the inner diameter din of the sensor head 1 is 1.5 mm and the outer diameter dout is 4.5 mm.
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Abstract
一种电流互感器,既具有锰铜分流器的低成本特性,又具有互感器类似的电流回路与电压回路的分离,有利于大幅度减轻三相智能电表的体积和重量,降低成本。它包括传感头(1)、导流条(2)和C形磁轭(3),其中,传感头(1),其输出端连接电流采样电路;导流条(2),穿过C形磁轭(3),其两端分别连接火线进线端和火线出线端,用于通电后在C形磁轭(3)的两个端部之间产生交变磁场;C形磁轭(3),所述传感头(1)通过C形磁轭(3)的开口端***,使C形磁轭(3)完全覆盖所述传感头(1),利用所述交变磁场在所述传感头(1)输出端感应出电动势。上述电流互感器主要应用于智能电表行业的电流测量。
Description
本发明涉及一种电流互感器,主要应用于智能电表行业的电流测量。
目前,智能电能表行业的电流测量回路,通常采用锰铜分流器和电磁式电流互感器。
锰铜分流式电流传感器成本低廉,其工作原理是电阻分压,由于锰铜的阻值随温度的变化较小,但离散性比较大,因此,在2.0级的单相电能表中被普遍采用。对普通220V 5(60)A的电能表,其取样电阻阻值约为250~500μΩ之间,发热量约1~2W。
锰铜分流器的优点是:加工简单、成本低廉、对直流分量和高次谐波都能测量。频率特性从DC-1MHz信号都能稳定传输(受电表计量回路采样率限制,实际使用范围通常在25kHz以下)。
锰铜分流器的缺点是:1、大电流时电阻发热量大,如果端子装配时螺丝压接不牢固,或者散热处理不当,很容易烧坏电表。2、由于金属成分和加工原因,导致电阻阻值离散性较大,阻值虽然随温度变化小,但还是受温度不规则地变化,因此,不适合高精度计量。
由于电压和电流信号公共端无法分离(见图1),不能直接被单相三线、两相两线、两相三线、三相三线、三相四线等需要多路电流取样测量的应用环境中。
从图1可以看出,采用锰铜分流器的电能表,火线L是作为计量回路的参考“地”使用的(计量芯片耐压一般在5V以下,如果将电压分压输入采用火线L,而以零线N作为地线,则计量芯片两个模拟输入的压差将达到220VAC,芯片承受不了),锰铜分流器是与火线“硬联接”的。
电流互感器是依据电磁感应原理的。如图2所示,电流互感器是由闭合的铁心和绕组组成,它的一次绕组匝数很少,串在需要测量的电流的线路中,因
此它经常有线路的全部电流流过,二次绕组匝数比较多,串接在测量仪表和保护回路中,电流互感器在工作时,它的二次回路始终是闭合的,因此测量仪表和保护回路串联线圈的阻抗很小,电流互感器的工作状态接近短路。互感器的优点是线性度好,稳定性高,准确度几乎不随温度变化,特别适合较高精度(0.5S级)的测量。
采用电流互感器的电能表的电流取样的参考端在二次侧与零线相连,因此一次侧电流输入是与电压回路是隔离的(见图3),因此,计量芯片的参考端可以是零线N,这样计量芯片的多个模拟输入端的电压差将控制在2V以下,在芯片通常的5V以下工作电压的允许范围内。电压与电流隔离的接入方法,特别适合要求两个以上电流回路测量的应用场合,如两相表、三相三线表和三相四线表等。
互感器的缺点是:体积大、成本高、抗过载能力弱,可测量信号的频率范围一般不超过2.5kHz,尤其是二次侧电流测量回路不能开路,否则会产生极高的电压而损坏测量电路!
发明内容
本发明的目的在于克服上述存在的问题,提供一种电流互感器,既具有锰铜分流器的低成本特性,又具有互感器类似的电流回路与电压回路的分离,有利于大幅度减轻三相智能电表的体积和重量,降低成本。
本发明的目的是通过如下技术方案来完成的,
电流互感器,它包括传感头、导流条和C形磁轭,其中,
传感头,其输出端连接电流采样电路;
导流条,穿过C形磁轭,其两端分别连接火线进线端和火线出线端,用于通电后在C形磁轭的两个端部之间产生交变磁场;
C形磁轭,所述传感头通过C形磁轭的开口端***,使C形磁轭完全覆盖所述传感头,利用所述交变磁场在所述传感头输出端感应出电动势。
所述C形磁轭的开口端内插有与其开口方向相同的C形绝缘片,所述传感头***C形绝缘片的开口端,使C形磁轭和C形绝缘片完全覆盖所述传感头;
所述导流条从C形磁轭和C形绝缘片所围空腔内穿过。
所述传感头为一采用导线均匀缠绕形成的空心螺线管,该空心螺线管两端连接所述电流采样电路。
所述空心螺线管的内径为0.5-1.5mm,缠绕匝数为1-10匝。
所述空心螺线管以嵌入方式固定于所述电流采样电路所在的PCB板上。
所述传感头为直接印刷于所述电流采样电路所在PCB板上的平面螺旋式或平面多边形螺旋式PCB型空心线圈。
所述PCB型空心线圈匝数为3匝,内径0.5-2mm,外径4.5mm。
所述导流条包括顺序相连形成U形的进线端连接段、感应段、出线端连接段;其中进线端连接段连接火线进线端,出线端连接段连接火线出线端,感应段穿过所述C形磁轭,使得所述C形磁轭至少覆盖部分感应段,形成导流条与C形磁轭相互勾拉的布置状态。
所述C形磁轭采用波莫合金、微晶合金或硅钢片制成。
所述C形磁轭采用波莫合金一体制成,或者采用微晶合金或波莫合金叠合而成,或者采用硅钢片叠合而成。
本发明与现有技术相比有如下优点和效果:
1、本发明采用结构更为简单小巧的传感头代替铁心和绕组,降低了贵金属材料(铜)的消耗,减轻了重量,减小了体积。2、很容易实现多相交流电测量中电压与电流回路的一次侧电气分离,简化了采样电路的电源设计。3、传感头以嵌入方式固定于所述PCB板上(空心螺线管),或者直接印刷于所述PCB板上(平面螺旋式或平面多边形螺旋式线圈),使得互感器能够在仅占用很小内部空间的情况下内置于电能表内部,从而大大减小电能表的整体体积。4、由于不含铁心,本发明无磁滞效应和磁饱和现象,带宽得到显著改善。5、传感头与被测电流之间没有电气连接,对被测回路影响极小。6、动态范围更宽,能够解决电气化铁路、大型电磁炉等冲击性负荷的电能计量难题。7、成本低。
图1是本发明背景技术中采用锰铜分流器的电表计量回路示意图。
图2是本发明背景技术中电流互感器的结构图。
图3是本发明背景技术中采用电流互感器的电表计量回路示意图。
图4是实施例1中传感头的示意图。
图5是图4传感头内嵌固定于PCB板上的结构示意图。
图6是实施例1互感器的主视图。
图7-1是整体式波莫合金C形磁轭的结构图。
图7-2是叠合式波莫合金或微晶合金C形磁轭的结构图。
图7-3是叠合式硅钢片C形磁轭的结构图。
图8是采用本发明互感器的电表计量回路示意图。
图9是实施例1应用于三个电流回路测量的结构示意图。
图10是图9的***图。
图11是实施例2中传感头的示意图。
图12是实施例3中传感头的示意图。
图13是实施例4中传感头的示意图。
图14是实施例5中传感头的示意图。
下面将结合附图对本发明做详细的介绍。
实施例1:
如图6、图8所示,本实施例电流互感器包括传感头1、导流条2和C形磁轭3,其中,
传感头1,如图4所示,为一采用导线均匀缠绕形成的空心螺线管,其输出端连接电流采样电路;
导流条2,包括顺序相连的进线端连接段2-1、感应段2-2、出线端连接段2-3;其中进线端连接段2-1连接火线进线端,出线端连接段2-3连接火线出线端,感应段2-2穿过所述C形磁轭3并对应布置于传感头1侧面,用于通电后在C形磁轭3开口端的上下两个平面之间,产生与电流强度呈线性关系的交变磁场;
C形磁轭3,所述传感头1通过C形磁轭3的开口端***,使C形磁轭3完全覆盖所述传感头1,利用所述交变磁场在所述传感头1输出端感应出电动势(具体为,导流条通电后产生变化的磁场,从而在传感头中感应出一个与电流变比成比例的电压信号其感应系数M与线圈系数kcoil和磁环导磁系数kMag的乘积相关,表示为M=kcoil*kMag)。本例中,C形磁轭3两个端部(开口端)之间的连线(C形磁轭开口端的上下两个平面之间的最短连线)与空心螺线管的轴线平行,一方面约束传感头1漏磁向外扩散,另一方面防止外部磁场对测量回路的干扰,提高测量精度;为了将外磁场干扰降低到最低限度,C形磁轭3覆盖在传感头1上的有效结构尺寸必须达到10mmx10mm以上。
为了确保实现电压与电路测量回路之间的分离,本实施例在所述C形磁轭3的开口端内插有与其开口方向相同的C形绝缘片4,所述传感头1***C形绝缘片4的开口端,使C形磁轭3和C形绝缘片4完全覆盖所述传感头1;所述导流条2从C形磁轭3和C形绝缘片4所围空腔(位于C形槽的底部)内穿过。
作为优选,所述螺线管以嵌入方式固定于所述电流采样电路所在的PCB板5上;如图5所示,具体为,在PCB板5上开设一槽,将螺线管放置于该槽内,将其两个输出端焊接于PCB板5上,并与PCB板上的电流采样电路相连。
所述螺线管的内径为0.5-1.5mm,分别对应直接接入式(如:Ib=5A~10A,最大电流输入60A~200A)或经互感器输入(如:额定电流In=1A,最大测量电流2A~6A)等不同应用需求;缠绕匝数为1-10匝,视PCB板5的厚度(螺线管的高度小于或等于PCB板的厚度)和测量端的信号输入范围而定。
为了解决导流条2与空心螺线管之间的绝缘问题,空心螺线管应使用漆包线绕制,且PCB板5上的导线需要盖绝缘绿油。
作为优选,所述进线端连接段2-1、感应段2-2、出线端连接段2-3顺序连接成U形,其中感应段2-2穿过所述C形磁轭3,使得所述C形磁轭3至少覆盖部分感应段2-2,形成导流条2与C形磁轭3相互勾拉的布置状态。
所述C型磁轭3的材料可以根据测量精确度的差异,选择波莫合金,微晶
合金,或者硅钢片等。本实施例中提供三种结构形式的C形磁轭,一种为整体式波莫合金制成,如图7-1所示,适用于电流在5-200A之间的大电流直接测量,优点是测量电流大,不易饱和,但线性度不足,需要进行分段补偿;一种为波莫合金或微晶合金叠合方式(10层)制成,如图7-2所示,适用于0.5S以上高准确度要求的小电流(0.3-10A)测量,波莫合金材料叠片的优点的测量范围宽,缺点是线性度需要补偿,而微晶合金叠片的优点是测量线性度极高,但量程范围略窄,适合0.2S级高精度测量应用场合;一种为硅钢片叠合式(10层),如图7-3所示,适用于1.0级的中等误差要求的小电流(1-10A)测量,成本较低。
如图9、图10所示,本实施例应用于三个电流回路测量时,需要设置三个并排布置的C形磁轭3和一个C形绝缘片4,每个C形磁轭3对应设置一个导流条2,C形绝缘片4同时***三个C形磁轭3的开口端。
本实施例采用电压和电流同步A/D采样的方式,依据电压信号的实测频率换算的周期作为空心螺线管的积分周期,然后由MCU或DSP开展数字积分。
实施例2:
如图11所示,本实施例与实施例1基本相同,区别在于:所述传感头1为直接印刷于所述电流采样电路所在PCB板5上的平面四边形螺旋式PCB型空心线圈,其匝数为3匝,内径din为2mm,外径dout为4.5mm。
实施例3:
如图12所示,本实施例与实施例1基本相同,区别在于:所述传感头1为直接印刷于所述电流采样电路所在PCB板5上的平面六边形螺旋式PCB型空心线圈,其匝数为3匝,内径din为2mm,外径dout为4.5mm。
实施例4:
如图13所示,本实施例与实施例1基本相同,区别在于:所述传感头1为直接印刷于所述电流采样电路所在PCB板5上的平面八边形螺旋式PCB型空心线圈,其匝数为3匝,内径din为2mm,外径dout为4.5mm。
实施例5:
如图14所示,本实施例与实施例1基本相同,区别在于:所述传感头1为
直接印刷于所述电流采样电路所在PCB板5上的平面螺旋式PCB型空心线圈,其匝数为3匝,内径din为2mm,外径dout为4.5mm。
实施例6:
本实施例与实施例2基本相同,区别在于:所述传感头1内径din为1.5mm,外径dout为4.5mm。
实施例7:
本实施例与实施例3基本相同,区别在于:所述传感头1内径din为1mm,外径dout为4.5mm。
实施例8:
本实施例与实施例4基本相同,区别在于:所述传感头1内径din为0.6mm,外径dout为4.5mm。
实施例9:
本实施例与实施例5基本相同,区别在于:所述传感头1内径din为1.5mm,外径dout为4.5mm。
Claims (10)
- 一种电流互感器,其特征在于:它包括传感头(1)、导流条(2)和C形磁轭(3),其中,传感头(1),其输出端连接电流采样电路;导流条(2),穿过C形磁轭(3),其两端分别连接火线进线端和火线出线端,用于通电后在C形磁轭(3)的两个端部之间产生交变磁场;C形磁轭(3),所述传感头(1)通过C形磁轭(3)的开口端***,使C形磁轭(3)完全覆盖所述传感头(1),利用所述交变磁场在所述传感头(1)输出端感应出电动势。
- 根据权利要求1所述的电流互感器,其特征在于:所述C形磁轭(3)的开口端内插有与其开口方向相同的C形绝缘片(4),所述传感头(1)***C形绝缘片(4)的开口端,使C形磁轭(3)和C形绝缘片(4)完全覆盖所述传感头(1);所述导流条(2)从C形磁轭(3)和C形绝缘片(4)所围空腔内穿过。
- 根据权利要求1或2所述的电流互感器,其特征在于:所述传感头(1)为一采用导线均匀缠绕形成的空心螺线管,该空心螺线管两端连接所述电流采样电路。
- 根据权利要求3所述的电流互感器,其特征在于:所述空心螺线管的内径为0.5-1.5mm,缠绕匝数为1-10匝。
- 根据权利要求3所述的电流互感器,其特征在于:所述空心螺线管以嵌入方式固定于所述电流采样电路所在的PCB板上。
- 根据权利要求1或2所述的电流互感器,其特征在于:所述传感头(1)为直接印刷于所述电流采样电路所在PCB板上的平面螺旋式或平面多边形螺旋式PCB型空心线圈。
- 根据权利要求6所述的电流互感器,其特征在于:所述PCB型空心线圈匝数为3匝,内径0.5-2mm,外径4.5mm。
- 根据权利要求1或2所述的电流互感器,其特征在于:所述导流条(2) 包括顺序相连形成U形的进线端连接段(2-1)、感应段(2-2)、出线端连接段(2-3);其中进线端连接段(2-1)连接火线进线端,出线端连接段(2-3)连接火线出线端,感应段(2-2)穿过所述C形磁轭(3),使得所述C形磁轭(3)至少覆盖部分感应段(2-2),形成导流条(2)与C形磁轭(3)相互勾拉的布置状态。
- 根据权利要求1或2所述的电流互感器,其特征在于:所述C形磁轭(3)采用波莫合金、微晶合金或硅钢片制成。
- 根据权利要求9所述的电流互感器,其特征在于:所述C形磁轭(3)采用波莫合金一体制成,或者采用微晶合金或波莫合金叠合而成,或者采用硅钢片叠合而成。
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