Current signal acquisition circuit for intelligent microgrid

Abstract

The utility model provides a current signal acquisition circuit for intelligent microgrid, including reference feedback circuit, signal sampling circuit and feedback proportional operation circuit, reference feedback circuit includes first operational amplifier, and the output of first operational amplifier connects secondary current feedback signal, and the noninverting input of first operational amplifier connects preset reference voltage signal, and the inverting input of first operational amplifier connects signal sampling circuit, signal sampling circuit includes second operational amplifier, and second operational amplifier connects primary current feedback signal, and second operational amplifier connects reference feedback circuit, and feedback proportional operation circuit includes third operational amplifier, and third operational amplifier receives secondary current feedback signal, and third operational amplifier connects signal sampling circuit, and the output of third operational amplifier exports current conversion signal, the utility model discloses the current conversion signal of output is more accurate.

Description

Technical Field

[0001] This utility model relates to the technical field of signal detection, specifically to a current signal acquisition circuit for smart microgrids. Background Technology

[0002] Microgrids are integrated systems of distributed energy resources and loads. Due to their small size, continuously adjustable capacity, and fast harmonic compensation tracking speed, microgrids are poised to become the mainstream equipment in the power quality management industry. Current acquisition circuits have become a key technology in the development of smart microgrid controllers. Accurate acquisition of the grid current is essential for precise grid management, ensuring the stable operation of the smart microgrid.

[0003] An existing AC current acquisition circuit includes a current acquisition network, an operational amplifier circuit, a reference voltage circuit, and a microcontroller. The output of the current acquisition network is connected to the non-inverting input of the operational amplifier circuit, the output of the reference voltage circuit is also connected to the non-inverting input of the operational amplifier circuit, and the output of the operational amplifier circuit is connected to the ADO input of the microcontroller. The operational amplifier circuit uses a differential amplifier circuit to amplify the input signal voltage through level shifting. However, this circuit does not compare the primary current with the secondary current, which may lead to inaccurate detection results when applied to the power grid. Utility Model Content

[0004] The primary objective of this invention is to provide a current signal acquisition circuit for intelligent microgrids that accurately detects grid current signals.

[0005] To achieve the primary objective of this invention, a current signal acquisition circuit for a smart microgrid is provided, comprising a reference feedback circuit, a signal sampling circuit, and a feedback proportional operation circuit. The reference feedback circuit includes a first operational amplifier, the output of which is connected to a secondary current feedback signal, the non-inverting input of which is connected to a preset reference voltage signal, and the inverting input of which is connected to the output of which is connected via a first resistor. The inverting input of which is connected to the signal sampling circuit. The signal sampling circuit includes a second operational amplifier, the non-inverting input of which is connected to a primary current feedback signal, and the inverting input of which is connected to the reference feedback circuit. The inverting input of which is connected to the output of which is connected via a second resistor. The feedback proportional operation circuit includes a third operational amplifier, the inverting input of which receives the secondary current feedback signal, the non-inverting input of which is connected to the signal sampling circuit, and the output of which outputs a current conversion signal.

[0006] As can be seen from the above scheme, the secondary current feedback signal and the preset reference voltage signal are processed by the reference feedback circuit to form a reference signal. Since this reference signal is connected to the inverting input of the first operational amplifier, and the input resistance of the inverting input of the first operational amplifier is extremely high, the current at the inverting input of the first operational amplifier is almost zero, and the voltage formed at the inverting input of the first operational amplifier is relatively stable. This increases the calculation accuracy of the second operational amplifier during subsequent signal sampling circuit processing. The reference signal is input to the inverting input of the second operational amplifier, and the primary current feedback signal is connected to its non-inverting input. After processing by the second operational amplifier, the accuracy of the primary current feedback signal acquisition is increased. The third operational amplifier amplifies the acquired signal to form a current-converted signal. Processing through three stages of operational amplifiers, and using the secondary current as a reference, makes the output current-converted signal more accurate.

[0007] In a further embodiment, the inverting input of the first operational amplifier is connected to the first terminal of a potentiometer, the second terminal of the potentiometer is connected to the first terminal of a third resistor, and the second terminal of the third resistor is connected to the inverting input of the second operational amplifier.

[0008] Therefore, the potentiometer can adjust the ratio between the reference signal and the final output current conversion signal, making subsequent detection more accurate.

[0009] In a further embodiment, the resistance value of the second resistor is the same as that of the third resistor.

[0010] Therefore, the resistance values ​​of the second resistor and the third resistor ensure that the voltage at the input of the second operational amplifier is twice the reference voltage minus the voltage of the primary current feedback signal, thereby improving the accuracy of the acquired primary current feedback signal.

[0011] In a further embodiment, the output terminal of the first operational amplifier is connected to the first terminal of the fourth resistor, and the second terminal of the fourth resistor is connected to the inverting input terminal of the third operational amplifier; the inverting input terminal of the third operational amplifier is connected to the first terminal of the fifth resistor, and the second terminal of the fifth resistor is connected to the output terminal of the third operational amplifier.

[0012] Therefore, the fourth and fifth resistors constitute the negative feedback proportional coefficient of the third operational amplifier.

[0013] In a further embodiment, the output of the second operational amplifier is connected to the first terminal of the sixth resistor, the second terminal of the sixth resistor is connected to the non-inverting input of the third operational amplifier, the non-inverting input of the third operational amplifier is also connected to the first terminal of the seventh resistor, and the second terminal of the seventh resistor is connected to the ground terminal.

[0014] Therefore, the sixth and seventh resistors constitute the in-phase scaling factor.

[0015] In a further proposed scheme, the primary current feedback signal is output from an external current transformer.

[0016] Therefore, it can be seen that the external current transformer can reduce the voltage of the primary current feedback signal, so that the primary current feedback signal does not break down the second operational amplifier.

[0017] In a further embodiment, the output of the third operational amplifier is connected to the processor.

[0018] This shows that the processor processes the current conversion signal. Attached Figure Description

[0019] Figure 1 This is a system structure block diagram of an embodiment of the current signal acquisition circuit for smart microgrids according to this utility model.

[0020] Figure 2 This is a circuit diagram of an embodiment of the current signal acquisition circuit for smart microgrids according to this utility model.

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0022] The current signal acquisition circuit for smart microgrids provided by this invention processes the primary current feedback signal through three operational amplifiers, making the output current conversion signal more accurate.

[0023] See Figure 1 The current signal acquisition circuit for smart microgrids includes a reference feedback circuit 1, a signal sampling circuit 2, and a feedback proportional calculation circuit 3. The reference feedback circuit 1 outputs a reference signal to the signal acquisition circuit 2, and the signal acquisition circuit 2 outputs a post-processed signal to the feedback proportional calculation circuit 3. The feedback proportional calculation circuit 3 receives the secondary current feedback signal acquired by the reference feedback circuit 1 and the post-processed signal output by the signal acquisition circuit 2, amplifies them, and outputs a current-converted signal.

[0024] See Figure 2 The reference feedback circuit includes a first operational amplifier U1C, the output of which is connected to a secondary current feedback signal V2, and the non-inverting input of which is connected to a preset reference voltage signal. The preset reference voltage signal is provided by the processor and has a voltage value of 2.5V.

[0025] The inverting input terminal of the first operational amplifier U1C is connected to the output terminal of the first operational amplifier U1C through the first resistor R2. That is, the inverting input terminal of the first operational amplifier U1C is connected to the first end of the first resistor R2, and the second end of the first resistor R2 is connected to the output terminal of the first operational amplifier U1C.

[0026] The inverting input of the first operational amplifier U1C is connected to the first terminal of potentiometer RP1. The second terminal of potentiometer RP1 is connected to the first terminal of the third resistor R1. The second terminal of potentiometer RP1 and the first terminal of the third resistor R1 form a reference signal V1. Potentiometer RP1 can adjust the ratio between the reference signal V1 and the final output current conversion signal VO, making subsequent detection more accurate.

[0027] The reference signal V1 is formed at the inverting input of the first operational amplifier U1C. Since the input resistance of the inverting input of the first operational amplifier is extremely high, the current at the inverting input of the first operational amplifier is almost zero. The voltage formed at the inverting input of the first operational amplifier is relatively stable, which increases the calculation accuracy of the second operational amplifier when the subsequent signal sampling circuit processes the signal.

[0028] The signal sampling circuit 2 includes a second operational amplifier U1B. The second terminal of the third resistor R1 is connected to the inverting input terminal of the second operational amplifier U1B, and the non-inverting input terminal of the second operational amplifier is connected to the primary current feedback signal VIN. The primary current feedback signal VIN is output after being stepped down by an external current transformer.

[0029] The inverting input terminal of the second operational amplifier U1B is connected to the output terminal of the second operational amplifier U1B through the second resistor R3. That is, the first end of the second resistor R3 is connected to the inverting input terminal of the second operational amplifier U1B, and the second end of the second resistor R3 is connected to the output terminal of the second operational amplifier U1B.

[0030] The resistance of the second resistor R3 is the same as that of the third resistor R1. The resistance values ​​of the second resistor R3 and the third resistor R1 make the voltage at the input terminal of the second operational amplifier U1B twice the reference voltage V1 minus the voltage of the primary current feedback signal, thereby improving the accuracy of the acquired primary current feedback signal.

[0031] The feedback proportional operation circuit 3 includes a third operational amplifier U1D. The inverting input terminal of the third operational amplifier U1D is connected to the output terminal of the first operational amplifier U1C through a fourth resistor R4. The non-inverting input terminal of the third operational amplifier U1D is connected to the output terminal U1B of the second operational amplifier through a sixth resistor R5. The output terminal of the third operational amplifier U1D outputs a current conversion signal VO.

[0032] The output of the first operational amplifier U1C is connected to the first terminal of the fourth resistor R4, and the second terminal of the fourth resistor R4 is connected to the inverting input of the third operational amplifier U1D. The inverting input of the third operational amplifier R4 is connected to the first terminal of the fifth resistor R6, and the second terminal of the fifth resistor R6 is connected to the output of the third operational amplifier U1D. The fourth resistor R4 and the fifth resistor R6 constitute the negative feedback proportional coefficient of the third operational amplifier U1D.

[0033] The output of the second operational amplifier U1B is connected to the first terminal of the sixth resistor R5, and the second terminal of the sixth resistor R5 is connected to the non-inverting input of the third operational amplifier U1D. The non-inverting input of the third operational amplifier U1D is also connected to the first terminal of the seventh resistor R7, and the second terminal of the seventh resistor U1D is connected to ground. The sixth resistor R5 and the seventh resistor R7 constitute the non-inverting proportional gain of the third operational amplifier U1D.

[0034] The first operational amplifier outputs a stable reference signal, the second operational amplifier outputs a precise post-processing signal, and the third operational amplifier amplifies the post-processing signal and the secondary current feedback signal, making the output current conversion signal more accurate.

[0035] The above is only a preferred embodiment of the present utility model, but the design concept of the utility model is not limited thereto. Without departing from the concept of the present utility model, more other equivalent embodiments may be included. Those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the protection scope of the present utility model.

Claims

1. A current signal acquisition circuit for smart microgrids, characterized in that, This includes a reference feedback circuit, a signal sampling circuit, and a feedback proportional calculation circuit; The reference feedback circuit includes a first operational amplifier, the output of which is connected to a secondary current feedback signal, the non-inverting input of which is connected to a preset reference voltage signal, the inverting input of which is connected to the output of which is connected through a first resistor, and the inverting input of which is connected to the signal sampling circuit. The signal sampling circuit includes a second operational amplifier. The non-inverting input of the second operational amplifier is connected to a primary current feedback signal, and the inverting input of the second operational amplifier is connected to the reference feedback circuit. The inverting input of the second operational amplifier is connected to the output of the second operational amplifier through a second resistor. The feedback proportional operation circuit includes a third operational amplifier. The inverting input of the third operational amplifier receives the secondary current feedback signal, the non-inverting input of the third operational amplifier is connected to the signal sampling circuit, and the output of the third operational amplifier outputs a current conversion signal.

2. The current signal acquisition circuit for smart microgrids according to claim 1, characterized in that: The inverting input terminal of the first operational amplifier is connected to the first terminal of a potentiometer, the second terminal of the potentiometer is connected to the first terminal of a third resistor, and the second terminal of the third resistor is connected to the inverting input terminal of the second operational amplifier.

3. The current signal acquisition circuit for smart microgrids according to claim 2, characterized in that: The resistance value of the second resistor is the same as that of the third resistor.

4. The current signal acquisition circuit for smart microgrids according to claim 1, characterized in that: The output terminal of the first operational amplifier is connected to the first terminal of the fourth resistor, and the second terminal of the fourth resistor is connected to the inverting input terminal of the third operational amplifier. The inverting input of the third operational amplifier is connected to the first terminal of the fifth resistor, and the second terminal of the fifth resistor is connected to the output of the third operational amplifier.

5. The current signal acquisition circuit for smart microgrids according to claim 4, characterized in that: The output terminal of the second operational amplifier is connected to the first terminal of the sixth resistor, and the second terminal of the sixth resistor is connected to the non-inverting input terminal of the third operational amplifier; The non-inverting input of the third operational amplifier is also connected to the first terminal of the seventh resistor, and the second terminal of the seventh resistor is connected to the ground terminal.

6. The current signal acquisition circuit for a smart microgrid according to any one of claims 1 to 5, characterized in that: The primary current feedback signal is output from an external current transformer.

7. The current signal acquisition circuit for a smart microgrid according to any one of claims 1 to 5, characterized in that: The output of the third operational amplifier is connected to the processor.

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