A multi-step adjustable current detection circuit and a current sensor

Abstract

This utility model relates to a multi-range adjustable current detection circuit and a current sensor. The current sampling and detection circuit amplifies the current through a two-stage amplifier circuit before inputting it into the controller. The first stage uses a differential amplifier circuit to amplify both positive and negative currents. The second stage uses a negative feedback amplifier circuit to amplify the positive current a second time using the forward amplifier circuit, and the reverse amplifier circuit to amplify the negative current a second time. An adjustable resistor is included in the second-stage amplifier circuit to allow for a suitable amplification factor. A switching circuit is used to control the switching between different ranges. The positive and negative current ranges do not interfere with each other, allowing for independent adjustment of the positive and negative ranges. The output signal is then converted from an analog to an analog-to-digital converter (AD) to achieve high-precision sampling of different current levels. This design can meet the sampling accuracy requirements of different current levels and improve the sampling resolution of small currents. It is compatible with different types and ranges of current sensors to achieve high-precision sampling of output currents at different ranges, providing better compatibility.

Description

Technical Field

[0001] This utility model relates to the field of electrical detection circuits and current sensors, and in particular to a multi-level adjustable current detection circuit and current sensor. Background Technology

[0002] Current sensing technology is a core foundation in fields such as power monitoring, industrial automation, and new energy equipment, and its measurement accuracy directly affects the safety and control efficiency of system operation. Traditional current sensors mostly use fixed-range Hall effect elements or shunt resistor structures to acquire current signals through a single detection channel. However, with the continuous expansion of the dynamic load range of modern electrical equipment, traditional solutions have gradually revealed the following technical shortcomings when dealing with wide-range current sensing: Fixed measurement ranges lead to insufficient dynamic adaptability: Fixed-range sensors are susceptible to noise interference in the low-current range, resulting in a significant decrease in effective resolution; when the current exceeds the preset range, saturation distortion occurs, failing to guarantee linearity across the entire range. Users are forced to rely on multiple devices with different ranges for segmented measurements, greatly increasing hardware costs and system complexity. For some high-current output applications, companies will classify products according to the current magnitude based on the customer's actual needs and select appropriate current sensors to achieve high-precision sampling for different current levels. Utility Model Content

[0003] The technical problem to be solved by this utility model is that the fixed range of the existing current detection circuit results in insufficient dynamic adaptability and cannot meet the customer's demand for multiple ranges. In view of the above-mentioned defects of the existing technology, a multi-range adjustable current detection circuit and current sensor are provided.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A multi-level adjustable current detection circuit is constructed, including a first amplifier circuit connected to a sampling input signal, which is a positive or negative current signal. The first amplifier circuit amplifies the sampling input signal. The circuit also includes a second amplifier circuit connected to the first amplifier circuit. The second amplifier circuit includes a forward amplifier circuit and / or a reverse amplifier circuit. The forward amplifier circuit amplifies the positive current signal, and the reverse amplifier circuit amplifies the negative current signal. The output terminals of the forward and reverse amplifier circuits are current sampling outputs, and the amplification factor of the forward amplifier circuit is ≥1.

[0005] Preferably, the first amplification circuit includes a differential amplifier, the current sampling signal is used as the input of the differential amplifier as a differential signal, and both the forward amplification circuit and the reverse amplification circuit are connected to a switching circuit, which controls the amplification factor of the forward amplification circuit and the reverse amplification circuit.

[0006] Preferably, the positive amplification circuit includes a first negative feedback amplifier. The negative terminal of the first negative feedback amplifier is connected to at least two sets of resistors arranged in parallel, and the resistance values ​​of the parallel resistors are different. The circuit is connected to a switching circuit through the at least two sets of resistors. The output signal of the first negative feedback amplifier is fed back to the inverting input terminal of the first negative feedback amplifier through a tenth resistor. The switching circuit includes at least two adjustment levels, and the adjustment levels correspond to the number of parallel resistors, with each level corresponding to one set of resistors. The positive terminal of the first negative feedback amplifier is connected to the first amplification circuit.

[0007] Preferably, the inverting amplifier circuit includes a second negative feedback amplifier. The negative terminal of the second negative feedback amplifier is connected to at least two sets of resistors arranged in parallel, and the resistance values ​​of the parallel resistors are different. The circuit is connected to a switching circuit through the at least two sets of resistors. The output signal of the second negative feedback amplifier is fed back to the inverting input terminal of the second negative feedback amplifier through a sixteenth resistor. The switching circuit includes at least two sets of adjustment levels, and the number of adjustment levels corresponds to the number of parallel resistors. Each set of adjustment levels corresponds to one set of resistors. The other end of the switching circuit is connected to the first amplifier circuit.

[0008] Preferably, the switching circuit is a DIP switch, a button, a MOSFET, or an independent switch corresponding to the adjustment level, with each set of independent switches corresponding to a parallel resistor and controlling the on / off state.

[0009] Preferably, the sixteenth resistor is a fixed resistor, and the parallel resistors are adjustable resistors, so that different amplification factors can be achieved by adjusting the resistance value of the adjustable resistors.

[0010] Preferably, the output terminal of the second amplifier circuit is connected to a clamping protection circuit, which clamps and protects the MCU input voltage.

[0011] Preferably, the output terminals of both the forward amplification circuit and the reverse amplification circuit are connected to diodes to clamp and protect the MCU input voltage, thereby ensuring the normal operation of the MCU.

[0012] Preferably, the first amplification circuit includes a differential amplifier, wherein the positive terminal of the differential amplifier is connected to a positive current signal through a first resistor, the negative terminal is connected to a current signal through a second resistor, and the differential signal is used as the input of the differential amplifier.

[0013] A current sensor is constructed, which includes a multi-level adjustable current detection circuit as described above for current detection.

[0014] The beneficial effects of this invention are as follows: The current sampling and detection circuit is amplified by a two-stage amplifier circuit before being input to the controller. The first stage uses a differential amplifier circuit to amplify both positive and negative currents. The second stage uses a negative feedback amplifier circuit consisting of a forward amplifier circuit and a reverse amplifier circuit. The forward amplifier circuit amplifies the positive current a second time, and the reverse amplifier circuit amplifies the negative current a second time. In the second-stage amplifier circuit, an adjustable resistor value is set to design a suitable amplification factor, and a switching circuit is used to control the switching of different ranges. The positive and negative current ranges do not interfere with each other, and can also be adjusted independently. After the output signal is converted from an analog to an analog signal, high-precision sampling of different current levels can be achieved. A clamping protection circuit is also designed for protection. This method can meet the sampling accuracy requirements of different current levels and improve the sampling resolution and accuracy of small currents. It is also compatible with different types and ranges of current sensors to achieve high-precision sampling of output currents of different ranges, providing better compatibility. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the utility model will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic block diagram of the current detection circuit according to a preferred embodiment of the present invention. Figure 2 This is a schematic block diagram of the second amplifier circuit of a preferred embodiment of the present invention. Figure 3 This is a schematic diagram of the specific circuit structure of the current detection circuit in a preferred embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of this utility model. Obviously, the described embodiments are some, but not all, embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0017] A preferred embodiment of this utility model provides a multi-level adjustable current detection circuit; such as... Figure 1As shown, the system includes a first amplifier circuit 20, through which a sampling input signal 10 is received, and a second amplifier circuit 30 connected to the first amplifier circuit 20. The output of the second amplifier circuit 30 is connected to a clamping protection circuit 40, and the output of the second amplifier circuit 30 is connected to a current sampling output 50. The sampling input signal 20 is amplified by the two-stage amplifier circuit and then output as a current sampling output 50, which is then input to the controller. The first amplifier circuit amplifies both positive and negative currents, while the second amplifier circuit amplifies either the positive or negative current a second time. A suitable amplification factor is set in the second amplifier circuit to achieve range setting, and switching between different ranges is possible. The positive and negative current ranges do not interfere with each other, and the ranges can be adjusted independently according to actual conditions. The sampling current output signal 50 is used as the MCU sampling input signal and undergoes AD conversion, enabling high-precision sampling at different current levels.

[0018] Specifically, such as Figure 2 As shown, the second amplifier circuit 30 includes a forward amplifier circuit 300 and an inverting amplifier circuit 301. The forward amplifier circuit is connected to the output of the first-stage differential operational amplifier and grounded through a switching circuit 60, with its output connected to a clamping protection circuit 40. The inverting amplifier circuit is connected to the first-stage differential operational amplifier through the switching circuit 60 and directly grounded, with its output connected to the clamping protection circuit 40 to clamp the MCU. This method allows the current detection circuit to simultaneously sample both positive and negative currents; alternatively, this design can be used to sample either positive or negative current separately.

[0019] Furthermore, such as Figure 3As shown, the current sensor samples the input signal 10 via U+ and U-. The first amplifier circuit 20 includes a differential amplifier U1. The positive terminal of the differential amplifier U1 is connected to U+ through a first resistor R1 and grounded through a third resistor R3. The negative terminal is connected to U- through a second resistor R2 and connected to the output terminal of the differential amplifier U1 through a fourth resistor R4. The positive amplifier circuit 300 includes a first negative feedback amplifier U2. The positive terminal of the first negative feedback amplifier U2 is connected to the output terminal of the differential amplifier U1 through a fifth resistor R5. The negative terminal is connected to the switch circuit 60 through a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9 connected in parallel. In this application, the switch circuit is configured with four positions. The sixth resistor R6, the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9, and their other ends are connected to one position of the switch circuit. The other end of the switch circuit is grounded. The first negative feedback amplifier U2 is connected to the inverting input terminal of the first negative feedback amplifier U2 through a tenth resistor R10. To achieve the switching of different amplification factors in the second amplifier circuit via the switching circuit K1, thereby enabling sampling and amplification of different current levels to meet the sampling requirements of multiple output current levels, this application designs a four-level toggle switch circuit 60. This circuit can be implemented using various forms of switches such as DIP switches and push-button switches, or it can use MOSFETs as switching transistors, with automatic control via an MCU. Alternatively, it can be designed as four independent switches connected to resistors R6, R7, R8, and R9 respectively. To adjust the amplification factor, the tenth resistor R10 is fixed, while the resistors R6, R7, R8, and R9 are set to different values ​​to adjust the amplification factor of the first negative feedback amplifier U2. Alternatively, the resistors R6, R7, R8, and R9 can be set as adjustable resistors to achieve adjustable amplification factor. Furthermore, the resistors can be connected in parallel via switch control to obtain different amplification factors, providing more range options.

[0020] Furthermore, such as Figure 3 As shown, the inverting amplifier circuit 301 includes a second negative feedback amplifier U3. The positive terminal of the second negative feedback amplifier U3 is grounded through the eleventh resistor R11, and the negative terminal is connected to the switching circuit 60 through the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14, and the fifteenth resistor R15 connected in parallel. The specific resistor values ​​of the inverting amplifier circuit 301 are designed the same as those of the forward amplifier circuit, and will not be repeated here. It should be noted that the first amplification of the current sampling is achieved through the first amplification circuit. However, in order to achieve a larger amplification factor, the amplification factor of the first negative feedback amplifier circuit is greater than or equal to 1. Therefore, the amplification factor of the sub-amplifier circuit is less than the total forward amplification factor.

[0021] Furthermore, such as Figure 3 As shown, the clamping protection 40 includes a first diode D1 or a second diode D2. The first diode D1 is connected to the output terminal of the first negative feedback amplifier U2, and the second diode D2 is connected to the output terminal of the second negative feedback amplifier U3. Since sampling the positive and negative currents separately will cause the MCU input voltage to exceed the input voltage range of the DSP IO pins, diode clamping is used to protect the MCU.

[0022] A preferred embodiment of the present invention provides a current sensor for current detection. The current sensor contains a multi-level adjustable current detection circuit as described above. The specific detection circuit structure is the same as described above and will not be repeated here.

[0023] It should be understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.

Claims

1. A multi-level adjustable current detection circuit, comprising a first amplification circuit, wherein the first amplification circuit is connected to a sampling input signal, the sampling input signal being a positive current signal or a negative current signal, and the first amplification circuit amplifies the sampling input signal, characterized in that: It also includes a second amplifier circuit connected to the first amplifier circuit. The second amplifier circuit includes a forward amplifier circuit and / or a reverse amplifier circuit. The forward amplifier circuit amplifies the positive current signal, and the reverse amplifier circuit amplifies the negative current signal. The output terminals of the forward amplifier circuit and the reverse amplifier circuit are current sampling outputs. The amplification factor of the forward amplifier circuit is ≥1.

2. The detection circuit according to claim 1, characterized in that: The first amplifier circuit includes a differential amplifier. The current sampling signal is used as the input of the differential amplifier with the differential signal. Both the forward amplifier circuit and the reverse amplifier circuit are connected to a switching circuit, which controls the amplification factor of the forward amplifier circuit and the reverse amplifier circuit.

3. The detection circuit according to claim 2, characterized in that: The positive amplification circuit includes a first negative feedback amplifier. The negative terminal of the first negative feedback amplifier is connected to at least two sets of resistors arranged in parallel, and the resistance values ​​of the parallel resistors are different. The circuit is connected to a switching circuit through the at least two sets of resistors. The output signal of the first negative feedback amplifier is fed back to the inverting input terminal of the first negative feedback amplifier through a tenth resistor. The switching circuit includes at least two sets of adjustment levels, and the number of adjustment levels corresponds to the number of parallel resistors, with each set of levels corresponding to one set of resistors. The positive terminal of the first negative feedback amplifier is connected to the first amplification circuit.

4. The detection circuit according to claim 2, characterized in that: The inverting amplifier circuit includes a second negative feedback amplifier. The negative terminal of the second negative feedback amplifier is connected to at least two sets of resistors arranged in parallel, and the resistance values ​​of the parallel resistors are different. The circuit is connected to a switching circuit through the at least two sets of resistors. The output signal of the second negative feedback amplifier is fed back to the inverting input terminal of the second negative feedback amplifier through a sixteenth resistor. The switching circuit includes at least two sets of adjustment levels, and the number of adjustment levels corresponds to the number of parallel resistors. Each set of adjustment levels corresponds to one set of resistors. The other end of the switching circuit is connected to the first amplifier circuit.

5. The detection circuit according to any one of claims 3 or 4, characterized in that: The switching circuit is a DIP switch, a button, a MOSFET, or an independent switch corresponding to the adjustment level. Each set of independent switches corresponds to a parallel resistor and controls the on / off state.

6. The detection circuit according to any one of claims 3 or 4, characterized in that: The sixteenth resistor is a fixed resistor, and the parallel resistors are adjustable resistors. Different amplification factors can be achieved by adjusting the resistance value of the adjustable resistors.

7. The detection circuit according to claim 1, characterized in that: The output of the second amplifier circuit is connected to a clamping protection circuit, which clamps and protects the MCU input voltage.

8. The detection circuit according to claim 7, characterized in that: Both the output terminals of the forward amplifier circuit and the reverse amplifier circuit are connected to diodes. The diodes clamp the input voltage to the MCU to protect the MCU from overclocking.

9. The detection circuit according to claim 1, characterized in that: The first amplifier circuit includes a differential amplifier. The positive terminal of the differential amplifier is connected to a positive current signal through a first resistor, and the negative terminal is connected to a current signal through a second resistor. The differential signal is used as the input of the differential amplifier.

10. A current sensor, characterized in that: The current sensor includes a multi-level adjustable current detection circuit as described in any one of claims 1-9 for current detection.

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