In-situ feedback probe and closed-loop current sensor

Abstract

The utility model provides an in-situ feedback probe and a closed-loop current sensor, the in-situ feedback probe comprises a magnetic sensing chip and a double-helix in-situ feedback coil, the magnetic sensing chip and the double-helix in-situ feedback coil are integrated on the same chip or integrated on the same PCB as the probe of the closed-loop current sensor, and the magnetic sensing chip and the double-helix in-situ feedback coil are integrated on the same PCB as the probe of the closed-loop current sensor. The in-place signal feedback coil and the magnetic sensing chip are closely arranged in an upper-lower layer mode in space distribution, the space interval is small, the feedback current needing to be applied to the in-place feedback coil is small, and the in-place signal feedback coil is applied to the closed-loop current sensor so that the power consumption of a system can be reduced. Compared with a common enameled wire feedback coil, the size of the feedback coil is greatly reduced, and miniaturization design of the closed-loop current sensor is facilitated.

Description

Technical Field

[0001] The utility model belongs to the technical field of current sensors, and in particular relates to an in-situ feedback probe and a closed-loop current sensor. Background Art

[0002] A current sensor is a detection device that can sense and detect the current information being detected, and then convert it into the desired electrical signal output or other forms of output signals based on appropriate calculations to achieve the purpose of signal transmission, processing, control, storage, etc. Current sensors are widely used in aerospace, smart grid, industrial control, automotive electronics and other fields. With the development of new energy vehicles, the automotive electronics field is the main market for current sensors, and the demand for current sensors in this field is increasing.

[0003] At present, common types of current sensors include Rogowski coil, Hall, fluxgate and magnetoresistive current sensors. Among them, Hall current sensors and magnetoresistive current sensors usually adopt a magnetic ring structure design with an open air gap, and the Hall or magnetoresistive sensor chip is set in the open air gap. When a signal current passes through the center current conductor, a magnetic field signal will be generated in the open air gap, and the sensor chip will generate a corresponding signal output to realize the detection of the signal current.

[0004] In addition, according to whether the signal processing of the current sensor system has a signal feedback design, it can be divided into open-loop and closed-loop types. Although the closed-loop structure is more complicated, it has more advantages than the open-loop current sensor in terms of performance, because the signal feedback structure is added to provide a negative feedback signal for the sensor chip, so that the sensor chip works in the linear range near the zero field, thus improving the linearity and measurement range of the current sensor system. However, the general closed-loop current sensor structure adopts the design method of winding multiple turns of enameled wire on the magnetic ring as a signal feedback coil to generate feedback signals, but this method has many disadvantages: on the one hand, it is necessary to increase the structural size of the system to complete the winding of the enameled wire; in addition, the number of turns of the feedback coil is limited by the magnetic ring structure; furthermore, the feedback magnetic field signal generated at the sensor chip depends on the magnetic induction effect of the magnetic ring structure. Therefore, for large current detection, more coil turns and larger currents are usually required, which means that the current sensor is larger in size and has higher power consumption. For example, in the patent application number CN202120885392.X, which is named as a closed-loop current sensor with a magnetic shunt structure, the feedback coil uses enameled wire wound around the magnetic ring, which increases the volume of the magnetic ring and has a large number of turns. Therefore, a power amplifier is required to drive the coil in the circuit design, which greatly increases the power consumption of the entire system. Summary of the invention

[0005] The utility model aims to address the defects of the prior art and propose an in-situ feedback probe and a closed-loop current sensor, aiming to achieve miniaturization of the closed-loop current sensor feedback probe and reduce the power consumption of the entire current sensor system.

[0006] A in-situ feedback probe includes a magnetic sensor chip and a double-helix in-situ signal feedback coil; the magnetic sensor chip and the in-situ signal feedback coil are integrated on the same chip, or integrated on the same PCB board as a probe of a closed-loop current sensor, and the in-situ signal feedback coil and the magnetic sensor chip are closely arranged in the upper and lower layers in terms of spatial distribution, with a small spatial spacing. Under the action of the driving current, the in-situ signal feedback coil generates a feedback magnetic field at the magnetic sensor chip. The in-situ signal feedback coil adopts a double-helix coil design structure, which can provide a larger effective feedback magnetic field in the direction of the sensitive axis of the magnetic sensor chip, can reduce the coil size, increase the feedback magnetic field strength, reduce the driving current, and reduce power consumption.

[0007] The closed-loop current sensor including the above-mentioned in-situ feedback probe has at least two sets of the above-mentioned double spiral coil in-situ feedback probes, which are not only arranged in the air gap of the open magnetic ring, but also in the area between the open magnetic ring and the center conductor. The design parameters of each set of probes can be different according to actual application needs.

[0008] The magnetic sensor chip and the double-helix on-site signal feedback coil are integrated together to form an on-site feedback probe of a closed-loop current sensor, which is used to detect and feedback the measured magnetic field signal. It is necessary to use a driving module on the current sensor signal processing circuit board to drive the double-helix on-site signal feedback coil to generate a feedback magnetic field to form a closed-loop current sensor.

[0009] When detecting low-frequency signals or DC signals, a modulation coil can be added to the probe board. The modulation coil uses modulation and demodulation technology to reduce the 1 / f noise of the magnetic sensor chip and improve the resolution of the current sensor when detecting low-frequency signals and DC signals.

[0010] The beneficial effects of the in-situ feedback probe structure proposed by the utility model include: achieving the miniaturized design requirements of the closed-loop current sensor feedback probe, improving the linearity and resolution of the closed-loop current sensor, and reducing the power consumption of the current sensor. It should be particularly pointed out that the utility model has obvious effects on the conventional current sensor in which the sensor chip is arranged in the open magnetic ring air gap, and for the sensor chip no longer in the open air gap, the effect of the double-helix in-situ signal feedback structure designed by the utility model is more prominent. Compared with the conventional wire coil wound on the magnetic ring structure, the feedback coil on the PCB board or on the chip integrated with the sensor chip can provide a larger effective feedback magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the closed-loop current sensor system in the embodiment of the utility model

[0012] Figure 2 This is a schematic diagram of the structure of the double helical coil in-situ feedback probe in Example 1 of the utility model;

[0013] Figure 3 This is a schematic diagram of the placement of the simulation observation point P and the observation line L1 in Example 1 of the utility model;

[0014] Figure 4 The simulation result of the in-situ signal feedback coil in Example 1 of the utility model;

[0015] Figure 5 This is a schematic diagram of the position structure of the modulation coil in Example 1 of the utility model;

[0016] Figure 6 This is a schematic diagram of the structure of the in-situ feedback probe in Embodiment 2 of the present utility model;

[0017] Figure 7 This is a process flow chart of the in-situ feedback probe in Example 2 of the utility model. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings and embodiments to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] Example 1

[0020] In this embodiment, the magnetic sensor chip, the in-position signal feedback coil and the modulation coil are integrated onto a PCB board as a probe of the current sensor;

[0021] The size of the coil is designed according to the process capabilities of the PCB board on the market. For example, the current process for making coils on PCB boards requires that the coil spacing must be above 0.15mm, the line width must be above 0.25mm, and the minimum thickness of the four-layer board is 0.8mm. The coil size is designed based on the corresponding relationship between the PCB board line width, copper cladding thickness and the current that can pass through the coil provided by the manufacturer.

[0022] The magnetic sensor chip of this embodiment is packaged in SOP8. The surface mount package can shorten the distance between the magnetic sensor chip and the PCB board. According to the packaging parameters of the magnetic sensor chip, the center point of the chip is about 1mm away from the plane of the PCB board. The PCB board adopts a four-layer board design. Considering that the current on the in-position signal feedback coil is larger than that on the modulation coil, the heat generated after power-on will affect the magnetic sensor chip. Therefore, the in-position signal feedback coil is arranged on the bottom layer of the PCB board.

[0023] like Figure 1 As shown, in this embodiment, the closed-loop current sensor has two sensing probes, which are used to measure different current ranges, one is set in the air gap of the magnetic ring, and the other is set in the area between the magnetic ring and the central conductive wire; therefore, there are also two groups of double-helix signal feedback coils integrated with the two current sensing probes, one is set in the air gap of the open magnetic ring, and the other is set in the area between the open magnetic ring and the central conductor. According to actual application needs, the design parameters of the two groups of probes can be different. Figure 2 As shown, the in-situ feedback probe includes an in-situ signal feedback coil 1 and a magnetic sensor chip 2. The in-situ signal feedback coil 1 and the magnetic sensor chip 2 are integrated onto the same PCB board 3 as a probe of a current sensor.

[0024] The in-position signal feedback coil 1 adopts a double spiral coil structure, which is beneficial to reducing the coil size and can also provide a larger effective feedback magnetic field in the sensitive axis direction of the magnetic sensor chip.

[0025] In order to determine the size of the in-situ signal feedback coil, the Maxwell software is used to simulate the in-situ signal feedback coil. When current is passed through the current wire to be measured, a primary magnetic field will be generated in the sensitive axis direction of the magnetic sensor chip. The magnetic induction intensity of the primary magnetic field is related to the distance between the current to be measured and the wire and the magnetic sensor chip. In this embodiment, the maximum magnetic induction intensity is about 20Oe. Since the center point of the magnetic sensor chip is 1mm away from the surface of the PCB board, the observation point P and the observation line L1 are set approximately 1.5mm above the center of the in-situ signal feedback coil. The relative positions are as follows: Figure 3 shown.

[0026] In this embodiment, the width of the in-position signal feedback coil is selected to be 0.4mm, the spacing is 0.17mm, and the copper coating thickness is 0.07mm; according to the relationship between the PCB board line width, copper coating thickness and the current that can pass through the coil provided by the manufacturer, the maximum current that can pass through the coil is passed; Figure 4As shown in the figure, the simulation results of the observation point P and the observation line L1 are shown. According to the simulation results, the size parameters of the in-situ signal feedback coil can be adjusted. By comparison, it can be found that the feedback field at the observation point P is the same as the feedback field generated by the same current passing through the single helical coil, but the total magnetic induction intensity of the double helical structure at the observation point has almost no components in other directions, so the double helical coil structure is selected in the design.

[0027] The function of the modulation coil is to modulate the working frequency band of the magnetic sensor chip from low frequency to high frequency, and use the modulation and demodulation technology to reduce the 1 / f noise of the magnetic sensor chip, thereby improving the resolution of the current sensor system. Therefore, when the current signal to be detected is a low frequency or DC signal, the modulation coil design can be added. The modulation coil is also simulated using Maxwell software. The structure of the modulation coil and the in-situ feedback probe is shown in the figure. Figure 5 As shown, the modulation coil 4 is arranged on the top layer of the PCB board, and the placement position of the modulation coil avoids the pins of the magnetic sensor chip. The modulation magnetic field is relatively small, so this embodiment adopts a single spiral coil structure to design the modulation coil. During simulation, the parameters of the line width, spacing and copper coating thickness of the modulation coil are also preset. When a certain current is passed through the modulation coil, the simulation result of the modulation magnetic field component at the observation point P is obtained, and then the size parameters of the modulation coil are adjusted to meet the modulation field intensity requirements.

[0028] Example 2

[0029] In this embodiment, the magnetic sensor chip and the in-situ signal feedback coil are integrated on the same chip through microelectronic technology, so that a more miniaturized chip-level in-situ feedback probe can be realized;

[0030] like Figure 6 As shown in FIG. 1 , in this embodiment, the distance between the in-situ signal feedback coil 5 and the silicon-based substrate 6 reaches the micron level, and the spatial spacing is smaller; therefore, the feedback magnetic field generated by the in-situ signal feedback coil in the sensitive axis direction of the magnetic sensor chip is larger, and compared with the in-situ signal feedback coil on the PCB board, the feedback current required to generate the same feedback magnetic field is smaller, so the size of the chip-level in-situ signal feedback coil can be designed to be smaller; however, the process capability and process requirements of the microelectronic process also need to be considered. The general process flow of the chip-level in-situ feedback probe is as follows: Figure 7 As shown, the details are as follows:

[0031] Step 1, depositing a magnetoresistive material on a silicon-based substrate to form a magnetoresistive unit structure and depositing an insulating layer 1;

[0032] Step 2: Open holes at the connection points of the magnetoresistor by photolithography and etching to prepare for subsequent metal interconnection lines;

[0033] Step 3, forming metal interconnection lines at the openings by photolithography or etching;

[0034] Step 4, depositing an insulating layer 2 on the metal interconnection line;

[0035] Step 5, depositing a metal conductive layer on the insulating layer 2;

[0036] Step 6: Pattern the metal conductive layer by photolithography, etching, etc. to form a double-helix metal coil structure, and open a hole for the PAD of the subsequent sensor chip.

[0037] When designing the coil, the in-situ signal feedback coil is simulated using Maxwell simulation software, and the simulation process is similar to that of Example 1. In addition, a modulation coil can also be integrated on the chip to modulate the working frequency band of the magnetic sensor chip from low frequency to high frequency, so that the current sensor system can meet higher performance requirements.

[0038] Although the specific implementation of the utility model is as above, the above content is only for the purpose of facilitating the understanding of the specific implementation of the utility model. Obviously, the above specific implementation is only exemplary and is not limited to the details of the above embodiments when conducting specific research. Therefore, those skilled in the art of the utility model can refer to and modify the specific implementation form and details without departing from the spirit and scope disclosed by the utility model, but the scope of patent protection of the utility model shall still be based on the scope defined by the attached claims.

Claims

1. An in-situ feedback probe, comprising a magnetic sensor chip and an in-situ feedback coil; characterized in that: Magnetic sensor chip and double-helix in-situ signal feedback coil; the magnetic sensor chip and the in-situ signal feedback coil are integrated on the same chip, or integrated on the same PCB board as a probe of a closed-loop current sensor, and the in-situ signal feedback coil and the magnetic sensor chip are closely arranged in the upper and lower layers in terms of spatial distribution, with a small spatial spacing.

2. The in-situ feedback probe according to claim 1, characterized in that: A modulation coil is also arranged on the probe substrate or the PCB board.

3. A closed-loop current sensor comprising the in-situ feedback probe according to claim 1, characterized in that: There are at least two sets of double helical coil in-situ feedback probes, which are not only arranged in the air gap of the open magnetic ring, but also in the area between the open magnetic ring and the center conductor; the in-situ feedback probe is matched with the driving module on the current sensor signal processing circuit board to drive the in-situ feedback coil to generate a feedback magnetic field to form a closed-loop current sensor.

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