Current sampling circuit

Abstract

The utility model provides a current sampling circuit, and belongs to the technical field of current sampling. The current sampling circuit comprises a reference voltage adjusting module, a differential amplification module and a signal adjusting module, the output end of the reference voltage regulation module is connected with the in-phase input end of the differential amplification module; the in-phase input end of the differential amplification module is connected with the first end of the current source, the inverted input end of the differential amplification module is connected with the second end of the current source, the output end of the differential amplification module is connected with the input end of the signal adjusting module, and the output end of the signal adjusting module is used for outputting a voltage signal corresponding to current; the reference voltage regulation module is configured to output a reference voltage. The problem that the current in the positive direction and the current in the negative direction cannot be effectively distinguished and accurately measured at the same time can be solved.

Description

Technical Field

[0001] This disclosure relates to the field of current sampling technology, and in particular to a current sampling circuit. Background Technology

[0002] In a bidirectional power supply, the current flows in two directions: positive and negative. In circuits, a precision resistor with a very small resistance or a Hall effect sensor is typically used to sample the current. The sampled value is then amplified and sent to the MCU for sampling and control.

[0003] When the current is in the positive direction, the output current sample is positive, and after being amplified in the same direction, it is also positive. The larger the current, the higher the amplified value. When the current is in the negative direction, after being amplified in the same direction, it is negative and cannot be recognized by the MCU. It needs to be amplified in the reverse direction to be positive for the MCU. The larger the current, the higher the value. However, the value at this time is the same as the value of positive current, and the MCU cannot distinguish whether it is a positive current or a negative current. Utility Model Content

[0004] This disclosure provides a current sampling circuit to solve the problem of not being able to effectively distinguish and accurately measure currents in both positive and negative directions simultaneously.

[0005] This disclosure provides a current sampling circuit, including:

[0006] Reference voltage regulation module, differential amplifier module, and signal conditioning module;

[0007] The output terminal of the reference voltage adjustment module is connected to the non-inverting input terminal of the differential amplifier module;

[0008] The non-inverting input terminal of the differential amplifier module is connected to the first terminal of the current source, the inverting input terminal of the differential amplifier module is connected to the second terminal of the current source, the output terminal of the differential amplifier module is connected to the input terminal of the signal conditioning module, and the output terminal of the signal conditioning module is used to output a voltage signal corresponding to the current.

[0009] The reference voltage regulation module is configured to output a reference voltage.

[0010] In one exemplary embodiment of this disclosure, the differential amplification module includes: sampling resistor RS, resistor R2, resistor R4, resistor R8, operational amplifier U1, and resistor R5;

[0011] The first end of the sampling resistor RS is connected to the first end of the current source, the second end of the sampling resistor RS is connected to the second end of the current source, the first end of the sampling resistor RS is connected to the non-inverting input of the operational amplifier U1 through the resistor R2, the second end of the sampling resistor RS is connected to the inverting input of the operational amplifier U1 through the resistor R4, the output of the operational amplifier U1 is connected to the inverting input of the operational amplifier U1 through the resistor R5, and the output of the operational amplifier U1 is connected to the input of the signal conditioning module.

[0012] The first end of the resistor R8 is connected to the output of the reference voltage regulation module.

[0013] In one exemplary embodiment of this disclosure, the signal conditioning module includes: a resistor R6 and a capacitor C5;

[0014] The first end of the resistor R6 is connected to the output end of the differential amplifier module, and the second end of the resistor R6 is grounded through the capacitor C5. The second end of the resistor R6 is used to output a voltage signal corresponding to the current.

[0015] In one exemplary embodiment of this disclosure, the signal conditioning module further includes: resistor R7 and operational amplifier U4;

[0016] The first end of resistor R7 is connected to the output of the differential amplifier module, the second end of resistor R7 is connected to the non-inverting input of operational amplifier U4, the output of operational amplifier U4 is connected to the inverting input of operational amplifier U4, and the output of operational amplifier U4 is connected to the first end of resistor R6.

[0017] In one exemplary embodiment of this disclosure, the reference voltage regulation module includes: a variable resistor RP1, a diode D1, an inductor L1, and a power supply chip U2;

[0018] The power supply terminal of the power chip U2 is connected to the VCC power supply. The first terminal of the inductor L1 is connected to the VCC power supply. The second terminal of the inductor L1 is connected to the power supply terminal of the power chip U2 and the anode of the diode D1. The cathode of the diode D1 is connected to the first terminal of the variable resistor RP1. The second terminal of the variable resistor RP1 is grounded. The sliding terminal of the variable resistor RP1 is connected to the feedback terminal of the power chip U2. The ground terminal of the power chip U2 is grounded. The cathode of the diode D1 is connected to the non-inverting input terminal of the differential amplifier module.

[0019] In one exemplary embodiment of this disclosure, the reference voltage adjustment module further includes: capacitor C2, resistor R3, and capacitor C3;

[0020] The cathode of diode D1 is grounded through capacitor C2. The cathode of diode D1 is connected to the first terminal of resistor R3. The second terminal of resistor R3 is grounded through capacitor C3. The second terminal of resistor R3 is connected to the non-inverting input terminal of the differential amplifier module.

[0021] The beneficial effects of the current sampling circuit provided in this embodiment are as follows: The reference voltage adjustment module of this embodiment can output a stable reference voltage, providing a reliable reference for subsequent modules and ensuring the stability of the entire circuit operation. The differential amplifier module can accurately convert the current signal into a voltage signal and can also distinguish between positive and negative current directions. For positive current, it outputs a value greater than the reference voltage; for negative current, it outputs a value less than the reference voltage but greater than zero, achieving accurate detection of current in both positive and negative directions. The signal adjustment module further processes the voltage output by the differential amplifier module to make it more stable, ultimately outputting a stable voltage signal that accurately corresponds to the current magnitude. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a current sampling circuit provided in an embodiment of this disclosure;

[0024] Figure 2 This is a circuit diagram of a current sampling circuit provided in an embodiment of this disclosure. Detailed Implementation

[0025] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0026] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0027] The implementation of this disclosure will be described in detail below with reference to the specific accompanying drawings:

[0028] Figure 1 This is a schematic diagram of a current sampling circuit provided in an embodiment of this disclosure. (Refer to...) Figure 1 The current sampling circuit includes:

[0029] Reference voltage regulation module, differential amplifier module, and signal conditioning module;

[0030] The output of the reference voltage regulation module is connected to the non-inverting input of the differential amplifier module;

[0031] The non-inverting input of the differential amplifier module is connected to the first terminal of the current source, the inverting input of the differential amplifier module is connected to the second terminal of the current source, the output of the differential amplifier module is connected to the input of the signal conditioning module, and the output of the signal conditioning module is used to output a voltage signal corresponding to the current.

[0032] The reference voltage regulation module is configured to output a reference voltage.

[0033] In this embodiment, the reference voltage adjustment module can output a positive reference voltage, such as 2.5V. The reference voltage is the benchmark for signal processing and comparison in the circuit. It is sent to the non-inverting input terminal of the differential amplifier module to provide a fixed reference point for current sampling.

[0034] When the current source output is 0, the differential amplifier module outputs 2.5V because it receives a 2.5V reference voltage at its non-inverting input. In the absence of current input, the circuit is in a balanced state, and the output voltage equals the reference voltage.

[0035] When the current source is in positive direction, the differential amplifier module can convert the current signal from the current source into a voltage signal. According to the principle of differential amplifier circuit, the input current will generate a voltage difference at the input terminal of the differential amplifier module. After amplification by the differential amplifier module, this voltage difference makes the output voltage greater than 2.5V. Furthermore, the magnitude of the output voltage is proportional to the magnitude of the input positive current, that is, the output voltage value can reflect the current magnitude when the current source is in positive direction.

[0036] When the current source is negative, a voltage difference will also be generated at the input of the differential amplifier module. After amplification by the differential amplifier module, the output voltage is less than 2.5V and greater than 0V. Similar to the positive current case, this output voltage value is proportional to the magnitude of the input negative current, reflecting the current magnitude when the current source is negative. Therefore, the differential amplifier module in this embodiment can detect and convert currents in both positive and negative directions, converting the current signal into a corresponding voltage signal output.

[0037] The signal conditioning module processes the voltage output from the differential amplifier module. Since the voltage signal output from the differential amplifier module may exhibit fluctuations or instability, the signal conditioning module uses specific circuitry, such as filtering and voltage regulation, to stabilize the output voltage, thereby more accurately reflecting the magnitude of the current source.

[0038] As can be seen from the above, the reference voltage adjustment module in this embodiment can output a stable reference voltage, providing a reliable reference for subsequent modules and ensuring the stability of the entire circuit operation. The differential amplifier module can accurately convert the current signal into a voltage signal and can also distinguish between positive and negative current directions. For positive current, it outputs a value greater than the reference voltage; for negative current, it outputs a value less than the reference voltage but greater than zero, achieving accurate detection of current in both positive and negative directions. The signal conditioning module further processes the voltage output from the differential amplifier module to make it more stable, ultimately outputting a stable voltage signal that accurately corresponds to the current magnitude.

[0039] like Figure 2 As shown, in one embodiment of this disclosure, the differential amplification module includes: sampling resistor RS, resistor R2, resistor R4, resistor R8, operational amplifier U1, and resistor R5;

[0040] The first end of the sampling resistor RS is connected to the first end of the current source, the second end of the sampling resistor RS is connected to the second end of the current source, the first end of the sampling resistor RS is connected to the non-inverting input of the operational amplifier U1 through resistor R2, the second end of the sampling resistor RS is connected to the inverting input of the operational amplifier U1 through resistor R4, the output of the operational amplifier U1 is connected to the inverting input of the operational amplifier U1 through resistor R5, and the output of the operational amplifier U1 is connected to the input of the signal conditioning module.

[0041] The first end of resistor R8 is connected to the output of the reference voltage regulation module.

[0042] In this embodiment, the sampling resistor RS is connected in series in the current source circuit. According to Ohm's law, when the current source passes through the sampling resistor RS, a voltage is generated across it, providing a basis for converting the current signal into a voltage signal for subsequent amplification and processing.

[0043] Resistors R2 and R4 introduce the voltage across the sampling resistor RS into the non-inverting and inverting input terminals of operational amplifier U1, respectively. Operational amplifier U1 amplifies the voltage difference between these two input terminals. This differential amplification method effectively suppresses common-mode signals and improves the circuit's anti-interference capability. Based on the characteristics of the operational amplifier, the amplification factor is mainly determined by the ratio of the feedback resistor R5 to the input resistor R2; in this circuit, the amplification factor is R5 / R2.

[0044] For example, assume that the resistance of resistors R2 and R4 is 1KΩ, the resistance of sampling resistor RS is 10mΩ, the resistance of resistors R5 and R8 is 20KΩ, and the reference voltage output by the reference voltage adjustment module is 2.5V.

[0045] When the current source is a positive current, i.e. A→B, the sampling resistor RS carries a positive current, and the voltage across the sampling resistor RS is positive at the top and negative at the bottom. After amplification, the output Vout = Vin*(R5 / R2) + 2.5V. Assuming that this is a 10A current source, then Vout = 10A*10mR*(20K / 1K) + 2.5V = 4.5V.

[0046] When the current source is a negative current, i.e. B→A, the sampling resistor RS carries a negative current, and the voltage across the sampling resistor RS is negative at the top and positive at the bottom. After amplification, the output Vout=Vin*(R5 / R2)+2.5V. Assuming that the current source is -10A, then Vout=-10A*10mR*(20K / 1K)+2.5V=0.5V.

[0047] When there is zero current, the output Vout is 2.5V. When there is positive current, the output value is greater than 2.5V, and the larger the current, the larger the value. When there is negative current, the output value is less than 2.5V, and the larger the current, the smaller the value. This is used to collect and distinguish between positive and negative current.

[0048] Resistor R8 is connected to the output of the reference voltage adjustment module, which provides a stable reference voltage for the differential amplifier module. This ensures that the output of op-amp U1 is at a specific reference level when there is no current input (i.e., zero current). Simultaneously, the reference voltage participates in the calculation during current signal conversion and amplification, enabling the output voltage to accurately reflect the magnitude and direction of the current.

[0049] The voltage signal amplified by operational amplifier U1 is output from its output terminal and connected to the input terminal of the signal conditioning module. The signal conditioning module further processes the signal and finally outputs a stable voltage signal that accurately corresponds to the magnitude and direction of the current.

[0050] like Figure 2 As shown, in one embodiment of this disclosure, the signal conditioning module includes: a resistor R6 and a capacitor C5;

[0051] The first end of resistor R6 is connected to the output of the differential amplifier module, and the second end of resistor R6 is grounded through capacitor C5. The second end of resistor R6 is used to output a voltage signal corresponding to the current.

[0052] In this embodiment, resistor R6 and capacitor C5 constitute an RC low-pass filter circuit. The voltage signal output by the differential amplifier module may contain some high-frequency noise, which may originate from electromagnetic interference in the circuit, switching actions of devices, etc. This RC low-pass filter circuit can remove this high-frequency noise, making the output voltage signal more stable and smooth, thereby more accurately reflecting the current magnitude of the current source.

[0053] like Figure 2 As shown, in one embodiment of this disclosure, the signal conditioning module further includes: resistor R7 and operational amplifier U4;

[0054] The first end of resistor R7 is connected to the output of the differential amplifier module, the second end of resistor R7 is connected to the non-inverting input of op-amp U4, the output of op-amp U4 is connected to the inverting input of op-amp U4, and the output of op-amp U4 is connected to the first end of resistor R6.

[0055] In this embodiment, operational amplifier U4 forms a follower. The follower acts as a signal buffer and isolation unit, enhancing the stability and anti-interference capability of the entire circuit. Combined with the RC filter circuit, it further improves the quality of the output signal, enabling the final output voltage signal to more accurately reflect the magnitude of the current source.

[0056] like Figure 2 As shown, in one embodiment of this disclosure, the reference voltage regulation module includes: a rheostat RP1, a diode D1, an inductor L1, and a power chip U2;

[0057] The power supply terminal of power chip U2 is connected to the VCC power supply. The first terminal of inductor L1 is connected to the VCC power supply. The second terminal of inductor L1 is connected to the power supply terminal of power chip U2 and the anode of diode D1. The cathode of diode D1 is connected to the first terminal of rheostat RP1. The second terminal of rheostat RP1 is grounded. The sliding terminal of rheostat RP1 is connected to the feedback terminal of power chip U2. The ground terminal of power chip U2 is grounded. The cathode of diode D1 is connected to the non-inverting input terminal of differential amplifier module.

[0058] In this embodiment, a reference voltage of 2.5V is assumed. Different current sources have different currents. If the current from the detected current source is too large, even with a 2.5V reference, the voltage after passing through the differential amplifier module will be negative and cannot be recognized by the MCU. Therefore, this embodiment includes a reference voltage adjustment module. This module can adjust for different current sources to output different reference voltage values ​​to meet different sampling environments.

[0059] A MAX5035 chip can be used as the power supply chip U2. Power supply chip U2 can output different reference voltages based on the voltage at the feedback terminal. It adjusts its operating state according to the feedback signal to output different reference voltages. If the feedback voltage increases, power supply chip U2 will adjust its output accordingly, lowering the reference voltage; conversely, if the feedback voltage decreases, power supply chip U2 will raise the reference voltage. This allows the reference voltage to be dynamically adjusted according to the setting of the variable resistor RP1.

[0060] Under the control of power chip U2, the energy stored in inductor L1 is transferred to subsequent circuits through diode D1. Diode D1 acts as a unidirectional conductor, preventing reverse current flow and ensuring that energy can only flow from inductor L1 to rheostat RP1 and subsequent circuits.

[0061] As can be seen from the above, different current sources may have different current magnitudes. If the detected current source is too large, using only a fixed reference voltage may result in a negative output voltage from the differential amplifier module, which cannot be recognized by the MCU. By using a reference voltage adjustment module, the reference voltage can be adjusted for different current source conditions, ensuring that the differential amplifier module can output appropriate voltage signals under various current source conditions. This guarantees that the subsequent MCU can correctly identify and process these signals, thus adapting to different sampling environments.

[0062] like Figure 2 As shown, in one embodiment of this disclosure, the reference voltage adjustment module further includes: capacitor C2, resistor R3, and capacitor C3;

[0063] The cathode of diode D1 is grounded through capacitor C2. The cathode of diode D1 is connected to the first terminal of resistor R3. The second terminal of resistor R3 is grounded through capacitor C3. The second terminal of resistor R3 is connected to the non-inverting input terminal of the differential amplifier module.

[0064] In this embodiment, capacitor C2, resistor R3, and capacitor C3 constitute a filter circuit. Filtering the reference voltage output from the reference voltage adjustment module effectively removes noise and fluctuations, ensuring that the differential amplifier module receives a stable and clean reference voltage, thereby guaranteeing the normal operation of the current sampling circuit.

[0065] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A current sampling circuit, characterized by, include: Reference voltage regulation module, differential amplifier module, and signal conditioning module; The output terminal of the reference voltage adjustment module is connected to the non-inverting input terminal of the differential amplifier module; The non-inverting input terminal of the differential amplifier module is connected to the first terminal of the current source, the inverting input terminal of the differential amplifier module is connected to the second terminal of the current source, the output terminal of the differential amplifier module is connected to the input terminal of the signal conditioning module, and the output terminal of the signal conditioning module is used to output a voltage signal corresponding to the current. The reference voltage regulation module is configured to output a reference voltage.

2. A current sampling circuit as claimed in claim 1, characterized in that The differential amplifier module includes: sampling resistor RS, resistor R2, resistor R4, resistor R8, operational amplifier U1, and resistor R5; The first end of the sampling resistor RS is connected to the first end of the current source, the second end of the sampling resistor RS is connected to the second end of the current source, the first end of the sampling resistor RS is connected to the non-inverting input of the operational amplifier U1 through the resistor R2, the second end of the sampling resistor RS is connected to the inverting input of the operational amplifier U1 through the resistor R4, the output of the operational amplifier U1 is connected to the inverting input of the operational amplifier U1 through the resistor R5, and the output of the operational amplifier U1 is connected to the input of the signal conditioning module. The first end of the resistor R8 is connected to the output of the reference voltage regulation module.

3. A current sampling circuit as claimed in claim 1, characterized in that The signal conditioning module includes: resistor R6 and capacitor C5; The first end of the resistor R6 is connected to the output end of the differential amplifier module, and the second end of the resistor R6 is grounded through the capacitor C5. The second end of the resistor R6 is used to output a voltage signal corresponding to the current.

4. A current sampling circuit as claimed in claim 3, characterized in that The signal conditioning module also includes: resistor R7 and operational amplifier U4; The first end of resistor R7 is connected to the output of the differential amplifier module, the second end of resistor R7 is connected to the non-inverting input of operational amplifier U4, the output of operational amplifier U4 is connected to the inverting input of operational amplifier U4, and the output of operational amplifier U4 is connected to the first end of resistor R6.

5. A current sampling circuit as claimed in claim 1, characterized in that The reference voltage adjustment module includes: a variable resistor RP1, a diode D1, an inductor L1, and a power chip U2; The power supply terminal of the power chip U2 is connected to the VCC power supply. The first terminal of the inductor L1 is connected to the VCC power supply. The second terminal of the inductor L1 is connected to the power supply terminal of the power chip U2 and the anode of the diode D1. The cathode of the diode D1 is connected to the first terminal of the variable resistor RP1. The second terminal of the variable resistor RP1 is grounded. The sliding terminal of the variable resistor RP1 is connected to the feedback terminal of the power chip U2. The ground terminal of the power chip U2 is grounded. The cathode of the diode D1 is connected to the non-inverting input terminal of the differential amplifier module.

6. A current sampling circuit as claimed in claim 5, characterized in that The reference voltage adjustment module also includes: capacitor C2, resistor R3 and capacitor C3; The cathode of diode D1 is grounded through capacitor C2. The cathode of diode D1 is connected to the first terminal of resistor R3. The second terminal of resistor R3 is grounded through capacitor C3. The second terminal of resistor R3 is connected to the non-inverting input terminal of the differential amplifier module.

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