Direct-current electric energy meter circuit suitable for anode and cathode current measurement

Abstract

The invention relates to the technical field of electric energy metering, in particular to a direct current electric energy meter circuit suitable for positive and negative electrode current measurement, which comprises a voltage sampling module, a current sampling module, a conversion module, an isolation module and a main control module, the input end of the voltage sampling module is connected to the conversion module, the conversion module is connected to the isolation module, the isolation module is connected to the main control module, the input end of the current sampling module is used for being connected with a diverter, and the output end of the current sampling module is connected to the conversion module. According to the invention, interference between the voltage sampling signal and the current signal is avoided, so that the accuracy of the signal is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric energy metering, and in particular to a DC electric energy meter circuit suitable for positive and negative current measurement and a DC electric energy meter applying this circuit. Background Art

[0002] With the wide application of electricity, the demand for electricity metering is increasing, and electricity metering is also of utmost importance. To meet the metering requirements, DC electric energy meters are designed to detect voltage and current.

[0003] In related technologies, when a DC electric energy meter detects a voltage source, the connection terminals for voltage detection need to be respectively connected to the positive and negative poles of the voltage source. When performing current detection, a shunt needs to be serially installed at the negative pole of the voltage source, and then the connection terminals for current detection are connected to the shunt. After that, voltage and current can be detected. In a DC electric energy meter, for the voltage sampling circuit and the current sampling circuit, there is a situation of sharing a signal loop, resulting in interference between the voltage sampling signal and the current sampling signal, making the signal inaccurate, and ultimately leading to inaccurate detection results. Summary of the Invention

[0004] In order to avoid interference between the voltage sampling signal and the current signal, thereby improving the accuracy of the signal, the present application provides a DC electric energy meter circuit suitable for positive and negative current measurement and a DC electric energy meter applying this circuit.

[0005] In a first aspect, a DC electric energy meter circuit suitable for positive and negative current measurement provided by the present application adopts the following technical solution: A DC electric energy meter circuit suitable for positive and negative current measurement includes a voltage sampling module, a current sampling module, a conversion module, an isolation module, and a main control module. The input end of the voltage sampling module is used to connect to a power supply to be measured. The input end of the voltage sampling module is connected to the conversion module. The conversion module is connected to the isolation module. The isolation module is connected to the main control module. The input end of the current sampling module is used to connect to a shunt, and the output end of the current sampling module is connected to the conversion module.

[0006] By adopting the above technical solution, both the voltage sampling module and the current sampling module are set up, and they are independent of each other. When collecting signals, they can be carried out simultaneously, and the interference between them is reduced, enabling the collected signals to be more accurate. Moreover, there is no requirement for the installation position of the shunt, improving the applicability. The conversion module is used to convert the collected analog signal into a digital signal, and then it is transmitted to the main control module through the isolation module. The set isolation module can achieve an isolation effect, isolate the high-voltage side from the low-voltage side, and also isolate interference, making the signal more accurate and stable.

[0007] Optionally, the voltage sampling module includes resistor R26, resistor R27, resistor R28, resistor R29, capacitor C20, capacitor C24, zener diode D5, and operational amplifier U11. The input end of the voltage sampling module includes input end U+ and input end U-. One end of resistor R26 is connected to input end U+ of the voltage sampling module, and the other end of resistor R26 is connected to resistor R27. The other end of resistor R27 is connected to resistor R28. The other end of resistor R28 is connected to the non-inverting input end of operational amplifier U11. One end of resistor R29 is connected to the connection point of resistor R27 and resistor R28. The other end of resistor R29 is connected to the ground terminal. The other end of resistor R29 is also connected to input end U-. One end of capacitor C24 is connected to the connection point of resistor R27 and resistor R28. The other end of capacitor C24 is connected to the ground terminal. The anode terminal of zener diode D5 is connected to the ground terminal. The cathode terminal of zener diode D5 is connected to the connection point of resistor R27 and resistor R28. The output end of operational amplifier D5 is connected to the conversion module. The inverting input end of operational amplifier D5 is connected to the output end of operational amplifier D5.

[0008] By adopting the above technical solution, the voltage sampling module uses resistor voltage reduction to realize the electrical measurement of the high-voltage power supply to be measured, and a zener diode D5 is provided to achieve the circuit protection function, avoiding the high-voltage breakdown of devices such as operational amplifier U11 when the resistor voltage reduction is abnormal. The operational amplifier U11 amplifies the signal and matches the impedance and outputs the signal to the conversion module.

[0009] Optionally, the current sampling module includes a resistor R1, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C8, an inductor L1, an inductor L2, a transient suppression diode D1, and an instrumentation amplifier U2. The input end of the current sampling module includes an input end I+ and an input end I-. One end of the resistor R1 is connected to the input end I+, the other end of the resistor R1 is connected to the resistor R4, the other end of the resistor R4 is connected to the input end I-, the connection point of the resistor R1 and the resistor R4 is connected to the ground end, one end of the transient suppression diode D1 is connected to the input end I+, the other end of the transient suppression diode D1 is connected to the input end I-, one end of the capacitor C3 is connected to the input end I+, the other end of the capacitor C3 is connected to the input end I-, one end of the inductor L1 is connected to the input end I+, the other end of the inductor L1 is connected to the non-inverting input end of the instrumentation amplifier U2, one end of the inductor L2 is connected to the input end I-, the other end of the inductor L2 is connected to the inverting input end of the instrumentation amplifier U2, one end of the capacitor C4 is connected to the non-inverting input end of the instrumentation amplifier U2, the other end of the capacitor C4 is connected to the inverting input end of the instrumentation amplifier U2, one end of the capacitor C2 is connected to the non-inverting input end of the instrumentation amplifier U2, the other end of the capacitor C2 is connected to the capacitor C8, the other end of the capacitor C8 is connected to the inverting input end of the instrumentation amplifier U2, the reference pin of the instrumentation amplifier U2 is connected to the ground end, and the output pin of the instrumentation amplifier U2 is connected to the conversion module.

[0010] By adopting the above technical solution, the current sampling module uses the design of signal amplification to amplify the signal transmitted by the shunt, and then uses the instrumentation amplifier for signal amplification and impedance matching, so as to output the signal to the conversion module.

[0011] Optionally, the conversion module includes a voltage ADC module and a current ADC module. The voltage ADC module is connected to the voltage sampling module, the current ADC module is connected to the current sampling module, and the voltage ADC module and the current ADC module are also both connected to the isolation module.

[0012] By adopting the above technical solution, the voltage ADC module is used to convert the signal collected by the voltage sampling module, so as to output the digital signal of voltage sampling. The current detection module is used to convert the signal collected by the current sampling module, so as to output the digital signal of current sampling. The two ADC modules convert the voltage and current signals respectively, which are independent of each other and reduce interference.

[0013] Optionally, the isolation module includes a voltage isolation chip U9 and a current isolation chip U7. The voltage isolation chip U9 is connected to the voltage ADC module, the current isolation chip U7 is connected to the current ADC module, and both the voltage isolation chip U9 and the current isolation chip U7 are also connected to the main control module.

[0014] By adopting the above technical solution, the voltage isolation chip U9 and the current isolation chip U7 are used to isolate digital signals, which can reduce interference and make the digital signals more accurate. Moreover, electrical isolation can also be achieved, that is, when an abnormality occurs on the high-voltage side, it can prevent the components on the low-voltage side from being damaged, realizing a protection function.

[0015] Optionally, it further includes an isolated power supply module. The isolated power supply module is connected to a first power supply module and a second power supply module. The input end of the isolated power supply module is used to connect to an external power supply, and the first power supply module and the second power supply module are used to supply power to the conversion module and the isolation module.

[0016] By adopting the above technical solution, the isolated power supply module is used to connect to an external power supply to obtain electrical energy, convert the voltage and then output it to the first power supply module and the second power supply module. The first power supply module and the second power supply module supply power independently, which can reduce the interference between power supply modules and the possibility of signal inaccuracy caused thereby.

[0017] Optionally, it further includes an isolated communication module. The input end of the isolated communication module is connected to the main control module, and the output end of the isolated communication module is used to connect to an external signal receiving module.

[0018] By adopting the above technical solution, using the isolated communication module for communication can isolate signal interference and implement various communication methods, improving applicability.

[0019] In a second aspect, a DC watt-hour meter provided by the present application adopts the following technical solution: A DC watt-hour meter includes a DC watt-hour meter circuit applicable to positive and negative current measurement as described in the first aspect.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. Both a voltage sampling module and a current sampling module are provided, and they are independent of each other. When collecting signals, they can be carried out simultaneously, and the interference between them is reduced, which can make the collected signals more accurate, and there is no requirement for the installation position of the shunt, improving applicability. The conversion module is used to convert the collected analog signals into digital signals, and then transmit them to the main control module through the isolation module. The provided isolation module can achieve an isolation function, can isolate the high-voltage side from the low-voltage side, and can also isolate interference to make the signals more accurate and stable; 2. The voltage ADC module is used to convert the signal collected by the voltage sampling module, so as to output the digital signal of voltage sampling. The current detection module is used to convert the signal collected by the current sampling module, so as to output the digital signal of current sampling. The two ADC modules convert the voltage and current signals respectively, which are independent of each other and reduce interference; 3. By using the voltage isolation chip U9 and the current isolation chip U7 to isolate the digital signal, the interference can be reduced, making the digital signal more accurate. Moreover, electrical isolation can also be achieved, that is, when an abnormality occurs on the high-voltage side, it can prevent the components on the low-voltage side from being damaged, realizing a protection function. Description of the Drawings

[0021] Figure 1 It is a block diagram of the overall connection of this embodiment.

[0022] Figure 2 It is the circuit schematic diagram of the isolated power supply module of this embodiment.

[0023] Figure 3 It is the circuit schematic diagram of the first power supply module of this embodiment.

[0024] Figure 4 It is the circuit schematic diagram of the second power supply module of this embodiment.

[0025] Figure 5 It is the circuit schematic diagram of the voltage sampling module of this embodiment.

[0026] Figure 6 It is the circuit schematic diagram of the current sampling module of this embodiment.

[0027] Figure 7 It is the circuit schematic diagram of the current ADC module and the current ADC module of this embodiment.

[0028] Figure 8 It is the circuit schematic diagram of the isolation module of this embodiment.

[0029] Figure 9 It is the circuit schematic diagram of the main control module of this embodiment.

[0030] Figure 10 It is the circuit schematic diagram of the isolated communication module of this embodiment.

[0031] Description of the reference numerals: 1. Voltage sampling module; 2. Current sampling module; 3. Conversion module; 31. Voltage ADC module; 32. Current ADC module; 4. Isolation module; 5. Main control module; 6. Isolated power supply module; 7. First power supply module; 8. Second power supply module; 9. Isolated communication module. Detailed Embodiment

[0032] The following is combined with the attachedFigure 1-10 Further detailed description of the present application is provided.

[0033] An embodiment of the present application discloses a DC watt-hour meter circuit applicable to positive and negative current measurement. Referring to Figure 1 , a DC watt-hour meter circuit applicable to positive and negative current measurement includes a voltage sampling module 1, a current sampling module 2, a conversion module 3, an isolation module 4, and a main control module 5, and further includes an isolated power supply module 6, a first power supply module 7, and a second power supply module 8. The input end of the voltage sampling module 1 is used to connect to a power supply to be measured, the input end of the voltage sampling module 1 is connected to the conversion module 3, the conversion module 3 is connected to the isolation module 4, the isolation module 4 is connected to the main control module 5, the input end of the current sampling module 2 is used to connect to a shunt, and the output end of the current sampling module 2 is connected to the conversion module 3.

[0034] Referring to Figure 2 , the input end of the isolated power supply module 6 includes a connection terminal DC+ and a connection terminal DC-, which are used to connect to an external power supply to achieve DC power supply. Then, the DC voltage is converted to obtain a 5V voltage and a 3.3V voltage. The 5V voltage is output from the power supply terminal 5V, and the 3.3V voltage is output from the power supply terminal 3.3V.

[0035] Referring to Figure 3 , the input end of the first power supply module 7 is connected to the power supply terminal 5V, and after isolation, voltage regulation, filtering and other processes, a 5V voltage is output from the power supply terminal 5V_U, and a 3.3V voltage is output from the power supply terminal 3.3V_U.

[0036] Referring to Figure 4 , the input end of the second power supply module 8 is also connected to the power supply terminal 5V, and after isolation, voltage regulation, filtering and other processes, a 5V voltage is output from the power supply terminal 5V_I, and a 3.3V voltage is output from the power supply terminal 3.3V_I.

[0037] Referring to Figure 5, the voltage sampling module 1 includes resistor R26, resistor R27, resistor R28, resistor R29, capacitor C20, capacitor C24, zener diode D5, and operational amplifier U11. The input terminal of the voltage sampling module 1 includes input terminal U+ and input terminal U-. One connection of resistor R26 is connected to input terminal U+ of the voltage sampling module 1, and the other connection of resistor R26 is connected to resistor R27. The other end of resistor R27 is connected to resistor R28. The other end of resistor R28 is connected to the non-inverting input terminal of operational amplifier U11. One end of resistor R29 is connected to the connection point of resistor R27 and resistor R28. The other end of resistor R29 is connected to the ground terminal. The other end of resistor R29 is also connected to input terminal U-. One end of capacitor C24 is connected to the connection point of resistor R27 and resistor R28. The other end of capacitor C24 is connected to the ground terminal. The anode terminal of zener diode D5 is connected to the ground terminal. The cathode terminal of zener diode D5 is connected to the connection point of resistor R27 and resistor R28. The output terminal of operational amplifier D5 is connected to the conversion module 3. The inverting input terminal of operational amplifier D5 is connected to the output terminal of operational amplifier D5.

[0038] Refer to Figure 6 , the current sampling module 2 includes resistor R1, resistor R4, capacitor C1, capacitor C2, capacitor C3, capacitor C4, capacitor C8, inductor L1, inductor L2, transient suppression diode D1, and instrumentation amplifier U2. The input terminal of the current sampling module 2 includes input terminal I+ and input terminal I-. One end of resistor R1 is connected to input terminal I+. The other end of resistor R1 is connected to resistor R4. The other end of resistor R4 is connected to input terminal I-. The connection point of resistor R1 and resistor R4 is connected to the ground terminal. One end of transient suppression diode D1 is connected to input terminal I+. The other end of transient suppression diode D1 is connected to input terminal I-. One end of capacitor C3 is connected to input terminal I+. The other end of capacitor C3 is connected to input terminal I-. One end of inductor L1 is connected to input terminal I+. The other end of inductor L1 is connected to the non-inverting input terminal of instrumentation amplifier U2. One end of inductor L2 is connected to input terminal I-. The other end of inductor L2 is connected to the inverting input terminal of instrumentation amplifier U2. One end of capacitor C4 is connected to the non-inverting input terminal of instrumentation amplifier U2. The other end of capacitor C4 is connected to the inverting input terminal of instrumentation amplifier U2. One end of capacitor C2 is connected to the non-inverting input terminal of instrumentation amplifier U2. The other end of capacitor C2 is connected to capacitor C8. The other end of capacitor C8 is connected to the inverting input terminal of instrumentation amplifier U2. The reference pin of instrumentation amplifier U2 is connected to the ground terminal. The output pin of instrumentation amplifier U2 is connected to the conversion module 3.

[0039] Refer to Figure 7, the conversion module 3 includes a voltage ADC module 31 and a current ADC module 32. The voltage ADC module 31 is connected to the voltage sampling module 1, and the current ADC module 32 is connected to the current sampling module 2. Both the voltage ADC module 31 and the current ADC module 32 are also connected to the isolation module 4.

[0040] Referring to Figure 8 , the isolation module 4 includes a voltage isolation chip U9 and a current isolation chip U7. The voltage isolation chip U9 is connected to the voltage ADC module 31, and the current isolation chip U7 is connected to the current ADC module 32. Both the voltage isolation chip U9 and the current isolation chip U7 are also connected to the main control module 5.

[0041] Referring to Figure 7 , specifically, the voltage ADC module 31 includes a SAR_ADC chip U10, a resistor R27, a resistor R30, a resistor R31, a capacitor C25, a capacitor C26, and a capacitor C27. The 1st pin, 3rd pin, and 5th pin of the SAR_ADC chip U10 are all connected to the ground terminal. The 2nd pin of the SAR_ADC chip U10 is connected to the power supply terminal 5V_U. The 4th pin of the SAR_ADC chip U10 is connected to the capacitor C25, and the other end of the capacitor C25 is connected to the ground terminal. The 6th pin of the SAR_ADC chip U10 is connected to the capacitor C26, and the other end of the capacitor C26 is connected to the ground terminal. The 7th pin of the SAR_ADC chip U10 is connected to the resistor R30, and the other end of the resistor R30 is connected to the voltage sampling module 1, that is, the other end of the resistor R30 is connected to the output terminal of the operational amplifier U11. The 8th pin of the SAR_ADC chip U10 is connected to the resistor R31, and the other end of the resistor R31 is connected to the ground terminal. One end of the capacitor C27 is connected to the 7th pin of the SAR_ADC chip U10, and the other end of the capacitor C27 is connected to the 8th pin of the SAR_ADC chip U10. The 14th pin of the SAR_ADC chip U10 is left floating, the 16th pin of the SAR_ADC chip U10 is connected to the power supply terminal 3.3V_U, and the other pins of the SAR_ADC chip U10 are connected to the voltage isolation chip U9.

[0042] The device composition of the current ADC module 32 is the same as that of the voltage ADC module 31, except for the device labels and connection pins, which will not be elaborated here. The connection relationship refers to Figure 7 .

[0043] In this embodiment, the SAR_ADC chip U10 and the SAR_ADC chip U1 are selected as chips of model SGM51622H, and chips of models SGM51613H, SGM51652H, ADS8689, ADS8681, and ADS8685 can also be selected.

[0044] The master control module 5 synchronously controls and communicates data with the voltage ADC module 31 and the current ADC module 32 through a single SPI bus daisy-chain topology, achieving the synchronization of voltage detection and current detection and improving the detection accuracy.

[0045] Referring to Figure 9 , the master control module 5 includes a processing chip U3 and the conventional peripheral circuits of the processing chip U3, which will not be elaborated here. The voltage isolation chip U9 and the current isolation chip U7 are both connected to the processing chip U3, and the connection pins refer to Figure 8 and Figure 9 .

[0046] In this embodiment, the processing chip U3 is selected as the chip with the model number HC32L176KATA-LQ64, and the chip with the model number HC32L196KCTA-LQ64 can also be selected.

[0047] Referring to Figure 10 , the master control module 5 is also connected with an isolated communication module 9. The isolated communication module 9 includes an RS485 communication chip U12. Among them, the switching end UART0_TR is connected to the processing chip U3 and is used to control the RS485 communication chip U12 to receive or send. When the processing chip U3 outputs a high level, that is, when the switching end UART0_TR is at a high level, the RS485 communication chip U12 is in the sending mode. When the processing chip U3 outputs a low level, that is, when the switching end UART0_TR is at a low level, the RS485 communication chip U12 is in the receiving mode. The connection end UART0_RXD and the connection end UART0_TXD are used for signal transmission, and the output end 485+ and the output end 485- are used to connect to an external signal receiving module.

[0048] The implementation principle of the DC watt-hour meter circuit applicable to positive and negative current measurement in the embodiment of the present application is as follows: Connect the input end of the voltage sampling module 1 to the power supply to be measured, connect the shunt in the circuit of the power supply to be measured, and there is no limitation on the connection position of the shunt. Then connect the input end of the current sampling module 2 to the shunt. That is, for current sampling in this circuit, the shunt at the connection position can be adapted, so as to achieve the purpose of adapting to different scenarios and improving the applicability.

[0049] After that, the voltage sampling module 1 and the current sampling module 2 are used for sampling, and the transmission paths of voltage sampling and current sampling are set independently. That is, the voltage sampling module 1 samples the voltage signal, which is amplified and then transmitted to the voltage ADC module 31 to realize analog-to-digital conversion, that is, convert the analog signal into a digital signal. The digital signal is transmitted to the master control module 5 after passing through the voltage isolation chip U9, and the voltage isolation chip U9 plays an isolation role. The transmission path of current sampling is similar to that of voltage sampling and will not be elaborated here.

[0050] Among them, when signal conversion is performed on the voltage ADC module 31 and the current ADC module 32, the main control module 5 sends the same CONVST / CS control instruction to the two ADC modules through the isolation module 4, so as to realize the synchronous control of two high-speed and high-precision SAR_ADC chips, that is, to realize the synchronous sampling control of voltage and current by the two SAR_ADC chips. Then, the analog signals received by the ADC modules are converted into SPI digital signals and transmitted to the main control module 5 through the isolation module 4. By controlling with the same control instruction, the synchronism of voltage and current sampling can be realized.

[0051] For separately setting two sampling transmission paths, the interference between voltage sampling and current sampling can be reduced, and the accuracy of sampling can be improved. The power supply part is also separately set. After the isolated power supply module 6 is connected to the external power supply, it can process the power supply of the external power supply to obtain 5V voltage output and 3.3V voltage output. Then, the first power supply module 7 and the second power supply module 8 separately process the two voltages to obtain different outputs. The first power supply module 7 is used to supply power to the transmission path of voltage sampling, and the second power supply module 8 is used to supply power to the transmission path of current sampling. By the way of separate power supply, the interference between voltage sampling and current sampling can also be reduced to improve the accuracy of the signal, thereby improving the accuracy of the detection result.

[0052] The voltage isolation chip U9 and the current isolation chip U7 can achieve electrical isolation, avoid interference on the high-voltage side, and can suppress electromagnetic interference, radio frequency interference, etc., so as to improve the integrity and accuracy of the signal.

[0053] The isolated communication module 9 can convert the detected data into RS485 signals and transmit them externally and can achieve isolation.

[0054] The embodiment of the present application discloses a DC watt-hour meter. A DC watt-hour meter includes a DC watt-hour meter circuit for measuring positive and negative currents disclosed above.

[0055] The above are all preferred embodiments of the present application. The protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A DC energy meter circuit suitable for measuring positive and negative currents, characterized in that: The invention comprises a voltage sampling module (1), a current sampling module (2), a conversion module (3), an isolation module (4) and a main control module (5), wherein the input end of the voltage sampling module (1) is used to connect to a power supply to be tested, the input end of the voltage sampling module (1) is connected to the conversion module (3), the conversion module (3) is connected to the isolation module (4), the isolation module (4) is connected to the main control module (5), the input end of the current sampling module (2) is used to connect to a shunt, and the output end of the current sampling module (2) is connected to the conversion module (3).

2. A DC electric energy meter circuit suitable for measuring positive and negative currents according to claim 1, characterized in that: The voltage sampling module (1) comprises a resistor R26, a resistor R27, a resistor R28, a resistor R29, a capacitor C20, a capacitor C24, a voltage zener diode D5, and an operational amplifier U11. The input end of the voltage sampling module (1) comprises an input end U+ and an input end U-. One end of the resistor R26 is connected to the input end U+ of the voltage sampling module (1). The other end of the resistor R26 is connected to the resistor R27. The other end of the resistor R27 is connected to the resistor R28. The other end of the resistor R28 is connected to the non-inverting input end of the operational amplifier U11. One end of the resistor R29 is connected to the resistor R2 7 and the connection point of the resistor R28, the other end of the resistor R29 is connected to the ground terminal, and the other end of the resistor R29 is also connected to the input terminal U-, one end of the capacitor C24 is connected to the connection point of the resistor R27 and the resistor R28, the other end of the capacitor C24 is connected to the ground terminal, the anode end of the voltage zener diode D5 is connected to the ground terminal, the cathode end of the voltage zener diode D5 is connected to the connection point of the resistor R27 and the resistor R28, the output end of the operational amplifier D5 is connected to the conversion module (3), and the inverting input end of the operational amplifier D5 is connected to the output end of the operational amplifier D5.

3. A DC electric energy meter circuit suitable for measuring positive and negative currents according to claim 1, characterized in that: The current sampling module (2) comprises a resistor R1, a resistor R4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C8, an inductor L1, an inductor L2, a transient suppression diode D1 and an instrumentation amplifier U2. The input end of the current sampling module (2) comprises an input end I+ and an input end I-. One end of the resistor R1 is connected to the input end I+, the other end of the resistor R1 is connected to the resistor R4, the other end of the resistor R4 is connected to the input end I-. The connection point between the resistor R1 and the resistor R4 is connected to the ground end. One end of the transient suppression diode D1 is connected to the input end I+, the other end of the transient suppression diode D1 is connected to the input end I-. One end of the capacitor C3 is connected to the input end I+, the other end of the capacitor C3 is connected to the input end I-, one end of the inductor L1 is connected to the input terminal I+, the other end of the inductor L1 is connected to the non-inverting input terminal of the instrument amplifier U2, one end of the inductor L2 is connected to the input terminal I-, the other end of the inductor L2 is connected to the inverting input terminal of the instrument amplifier U2, one end of the capacitor C4 is connected to the non-inverting input terminal of the instrument amplifier U2, the other end of the capacitor C4 is connected to the inverting input terminal of the instrument amplifier U2, one end of the capacitor C2 is connected to the non-inverting input terminal of the instrument amplifier U2, the other end of the capacitor C2 is connected to the capacitor C8, the other end of the capacitor C8 is connected to the inverting input terminal of the instrument amplifier U2, the reference pin of the instrument amplifier U2 is connected to the ground terminal, and the output pin of the instrument amplifier U2 is connected to the conversion module (3).

4. A DC electric energy meter circuit suitable for measuring positive and negative currents according to any one of claims 1 to 3, characterized in that: The conversion module (3) comprises a voltage ADC module (31) and a current ADC module (32); the voltage ADC module (31) is connected to the voltage sampling module (1); the current ADC module (32) is connected to the current sampling module (2); and the voltage ADC module (31) and the current ADC module (32) are both connected to the isolation module (4).

5. A DC electric energy meter circuit suitable for measuring positive and negative currents according to claim 4, characterized in that: The isolation module (4) comprises a voltage isolation chip U9 and a current isolation chip U7; the voltage isolation chip U9 is connected to the voltage ADC module (31); the current isolation chip U7 is connected to the current ADC module (31); and the voltage isolation chip U9 and the current isolation chip U7 are also connected to the main control module (5).

6. A DC electric energy meter circuit suitable for measuring positive and negative currents according to claim 1, characterized in that: It also comprises an isolation power supply module (6), the isolation power supply module (6) being connected to a first power supply module (7) and a second power supply module (8), the input end of the isolation power supply module (6) being used to connect to an external power supply, the first power supply module (7) and the second power supply module (8) being used to supply power to the conversion module (3) and the isolation module (4).

7. A DC electric energy meter circuit suitable for measuring positive and negative currents according to claim 1, characterized in that: It also comprises an isolation communication module (9), the input end of the isolation communication module (9) being connected to the main control module (5), and the output end of the isolation communication module (9) being used to connect to an external signal receiving module.

8. A DC electric energy meter, characterized in that: It comprises a DC electric energy meter circuit suitable for measuring positive and negative currents as described in any one of claims 1 to 7.

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