CN219496521U - Direct current electric energy meter circuit suitable for DC1500V voltage input - Google Patents
Direct current electric energy meter circuit suitable for DC1500V voltage input Download PDFInfo
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- CN219496521U CN219496521U CN202320679976.0U CN202320679976U CN219496521U CN 219496521 U CN219496521 U CN 219496521U CN 202320679976 U CN202320679976 U CN 202320679976U CN 219496521 U CN219496521 U CN 219496521U
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Abstract
The utility model relates to a direct current electric energy meter circuit suitable for DC1500V voltage input, which comprises: the direct-current electric energy metering circuit measures the voltage, current and electric energy parameters of a direct-current bus through a metering chip, and performs data interaction with an SPI (serial peripheral interface) of an MCU (micro control Unit) in the MCU circuit through an SPI of the metering chip; the isolation circuit realizes SPI digital communication between the metering chip and the MCU, and the electric gap and the creepage distance between the direct-current electric energy metering circuit and the MCU circuit can meet DC1500V voltage input through serial connection of the first isolation circuit and the second isolation circuit; the MCU circuit reads the voltage, current and electric energy parameters measured by the metering chip; the communication circuit externally provides an RS485 hardware interface for data communication with the monitoring system, and the MCU circuit is connected with the communication circuit through a serial port; the power supply circuit outputs two paths of isolated power supplies through the switching transformer and provides working power supplies for the isolation circuit, the MCU circuit and the communication circuit respectively.
Description
Technical Field
The utility model relates to the technical field of direct current electric energy meters, in particular to a direct current electric energy meter circuit suitable for DC1500V voltage input.
Background
The direct current electric energy meter plays an increasingly important role in the fields of direct current charging piles, solar photovoltaics and the like, the maximum range of a voltage measuring circuit of the conventional direct current electric energy meter in the market reaches DC1000V, according to standard IEC61010-2-030 (safety requirements of electric equipment for measurement, control and laboratory are 2-030 parts: special requirements of test and measuring circuits), the electric gap and creepage distance between a high-voltage measuring signal (direct current bus voltage and current) and a low-voltage signal (such as MCU circuits and RS485 circuits) in some products can only meet the basic insulation of overvoltage class II (overvoltage class II: overvoltage born on energy consumption equipment supplied by a power distribution device), but cannot meet the double insulation requirements of overvoltage class III (overvoltage class III: equipment installed in the power distribution device, and the use safety and applicability of the equipment are required to meet the overvoltage born by special requirements), and the products have electric safety hidden dangers in use; at present, voltage and current input of a direct current electric energy meter are generally four-terminal input (positive and negative voltage signal terminals and positive and negative current signal terminals), and the accuracy of current signals sampled by a shunt can be influenced by the negative voltage signal terminals of some on-site voltage signals at different wiring positions of the negative voltage terminals of a direct current bus, the voltage of the current solar photovoltaic industry reaches DC1500V high voltage, the conventional direct current electric energy meter in the market does not meet the safety rule requirement of DC1500V, particularly in the application occasions with high overvoltage level and high altitude, the requirements on the electric gap and creepage distance of products are stricter due to the influence of high overvoltage level and high altitude on the safety rule performance of the products, and the solar photovoltaic market is demanding a direct current electric energy meter meeting the standard IEC61010-2-030 overvoltage class III and achieving double-insulation DC1500V voltage input.
Disclosure of Invention
Aiming at the problems and defects existing in the prior art, the utility model provides a direct current electric energy meter circuit suitable for DC1500V voltage input.
The utility model solves the technical problems by the following technical proposal:
the utility model provides a direct current electric energy meter circuit suitable for DC1500V voltage input, which is characterized by comprising a direct current electric energy metering circuit, an isolation circuit, an MCU circuit, a communication circuit and a power supply circuit.
The maximum value of the direct current bus voltage in the direct current electric energy metering circuit is DC1500V, bus current is sampled through the current divider, three input terminals U+ end, I+ end and I-end of the direct current electric energy metering circuit are sequentially connected with the direct current bus voltage positive end U+ of the electric equipment and the output signal I+ end and I-end of the current divider, and the direct current bus voltage, current and electric energy electric parameters are measured through the metering chip, and data interaction is carried out through an SPI (serial peripheral interface) of the metering chip and an SPI (serial peripheral interface) of an MCU (micro control unit) in the MCU circuit.
The output end of the isolation circuit is connected with the SPI port of the metering chip in the direct-current electric energy metering circuit, the input end of the isolation circuit is connected with the SPI port of the MCU in the MCU circuit, the isolation circuit realizes the SPI digital communication of the metering chip and the MCU, and the electric gap and the creepage distance between the direct-current electric energy metering circuit and the MCU circuit meet the DC1500V voltage input and the double insulation requirement of the overvoltage class III through the serial connection of the first isolation circuit and the second isolation circuit.
The MCU circuit is used for reading voltage, current and electric energy parameters measured by the metering chip through the SPI port.
The communication circuit is used for externally providing an RS485 hardware interface to carry out data communication with the monitoring system, and the MCU circuit is connected with the communication circuit through a serial port.
The power supply circuit is used for outputting two paths of isolated power supplies through the switching transformer, and is respectively connected with the isolation circuit, the MCU circuit and the communication circuit to provide working power supplies for the isolation circuit, the MCU circuit and the communication circuit.
The utility model has the positive progress effects that:
the direct current electric energy meter circuit suitable for DC1500V voltage input can realize larger electric gap and creepage distance through the two-stage isolation circuit, solves the problem of DC voltage safety regulation of a conventional direct current electric energy meter, particularly improves the safety performance of products when DC1500V high voltage input in the solar photovoltaic industry is applied to high-altitude occasions with high overvoltage levels, simultaneously provides a three-terminal design scheme of voltage and current, solves the problem that the conventional direct current electric energy meter influences the precision of current signals sampled by a shunt when the negative terminal of a field voltage signal is connected with the negative terminal of a direct current bus, reduces wiring of users, supports DC 9V-36V in the input range of an auxiliary power supply of the electric energy meter, meets the requirements of users with different DC12V or DC24V on the field, is more flexible and convenient to use, and improves the market competitiveness of the products.
Drawings
Fig. 1 is a block diagram of a DC power meter circuit suitable for DC1500V voltage input according to the present utility model.
Fig. 2 is a circuit diagram of the dc power metering circuit 1 of the present utility model.
Fig. 3 is a circuit diagram of the isolation circuit 2 of the present utility model.
Fig. 4 is a circuit diagram of the MCU circuit 3 of the present utility model.
Fig. 5 is a circuit diagram of the communication circuit 4 of the present utility model.
Fig. 6 is a circuit diagram of the power supply circuit 5 of the present utility model.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
As shown in fig. 1, the present embodiment provides a direct current electric energy meter circuit suitable for DC1500V voltage input, which includes a direct current electric energy metering circuit 1, an isolation circuit 2, an MCU circuit 3, a communication circuit 4, and a power supply circuit 5.
The maximum value of the direct current bus voltage in the direct current electric energy metering circuit 1 is DC1500V, bus current is sampled through a shunt, three input terminals U+ end, I+ end and I-end of the direct current electric energy metering circuit 1 are sequentially connected with a direct current bus voltage positive end U+ of the electric equipment and output signals I+ end and I-end of the shunt, and the direct current bus voltage, current and electric energy electric parameters are measured through a metering chip, and data interaction is carried out through an SPI (serial peripheral interface) of the metering chip and an SPI (serial peripheral interface) of an MCU (micro control Unit) in the MCU circuit.
As shown in FIG. 2, the voltage and current input signals in the DC electric energy metering circuit 1 are designed by three terminals, the voltage signal negative terminal U-and the current signal negative terminal I-are the same input terminal, the voltage signal negative terminal U-is not required to be connected to the terminal of the electric energy meter in the field, the shunt output signal negative terminal I-is the common terminal of the voltage signal negative terminal U-and the current signal negative terminal I-, the positive terminal input U+ of DC1500V bus voltage is connected with the voltage channel of the metering chip after passing through the resistor divider circuit, wherein the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the seventh resistor R7 sequentially form a resistor divider circuit, one end of the voltage divider circuit is connected with the positive terminal input U+ of DC1500V DC bus voltage, the other end of the voltage divider circuit is connected with the reference ground signal GND2, the DC bus voltage sampling signal on the seventh resistor R7 is connected with the positive terminal pin 8 of the third integrated circuit U3 voltage channel after passing through the sixth resistor R6 and the RC filter circuit formed by the first capacitor C1, and the negative terminal U2 is connected with the reference signal GND2 through the RC filter circuit, and the other end of the third resistor R2 is connected with the reference signal GND 2.
The DC bus current is sampled and output through a shunt to form a mV signal which is connected with a current channel of a third integrated circuit U3, the positive end I+ of the output signal of the shunt is connected with one end of a fifth magnetic bead L5, a thirteenth resistor R13 and a twelfth capacitor C12 form an RC filter circuit, one end of the RC filter circuit is connected with the other end of the fifth magnetic bead L5, the other end of the RC filter circuit is connected with a positive end pin 4 of the current channel of the third integrated circuit U3, the negative end I-of the output signal of the shunt is connected with one end of a fourth magnetic bead L4, the other end of the fourth magnetic bead L4 is connected with a reference ground signal GND2, one end of the RC filter circuit is connected with a negative end pin 5 of the current channel of the third integrated circuit U3, the other end I-of the RC filter circuit is connected with a reference ground signal GND2, the negative end of the DC bus voltage input U-is short-circuited with the negative end I-of the output signal of the shunt, the sixth integrated circuit U6 provides a 3.3V working power supply (+ 3.3V2) for the third integrated circuit U3, and the sixth integrated circuit U6 provides a DC power supply 5V 2.
The output end of the isolation circuit 2 is connected with the SPI port of the metering chip in the direct-current electric energy metering circuit 1, the input end of the isolation circuit 2 is connected with the SPI port of the MCU in the MCU circuit 3, the isolation circuit 2 realizes SPI digital communication of the metering chip and the MCU, and the electric gap and the creepage distance between the direct-current electric energy metering circuit 1 and the MCU circuit 3 meet the DC1500V voltage input and the double insulation requirement of the overvoltage class III through the serial connection of the first isolation circuit 21 and the second isolation circuit 22.
As shown in fig. 3, the SPI port of the metering chip in the DC power metering circuit 1 and the SPI port of the MCU in the MCU circuit 3 are connected through an SPI digital isolator in the isolation circuit 2, so that digital signal communication between the metering chip and the MCU is realized, and an isolated DC5V working power supply input is provided for the DC power metering circuit 1.
The isolation circuit 2 comprises a first isolation circuit 21 and a second isolation circuit 22, wherein an input side I/O signal of the first isolation circuit 21 is connected with an SPI port of the MCU, an output side I/O signal of the first isolation circuit 21 is connected with an input side I/O signal of the second isolation circuit 22, an output side I/O signal of the second isolation circuit 22 is connected with an SPI port of the metering chip, and the two isolation circuits form a series circuit to realize two-stage electrical isolation of the SPI port of the metering chip and the MCU circuit.
The first isolation circuit 21 comprises a digital isolator U7 and a power supply module U4, wherein input side I/O signals (8209_CS, 8209_SCLK, 8209_MOSI and 8209_MISO) of the digital isolator U7 are connected with SPI interfaces of the MCU circuit 3, output side I/O signals of the digital isolator U7 are connected with input side I/O signals of the second isolation circuit 22, an input power supply end of the power supply module U4 is provided with DC5V power supply (+ 5V) by the power supply circuit 5, output DC5V power supply (+ 5V 1) of the power supply module U4 supplies power to the output side power supply end of the digital isolator U7 and the input side power supply end of the second isolation circuit 22, the input side power supply end of the digital isolator U7 is provided with 3.3V power supply in the MCU circuit 3, the digital isolator U7 is an ultra-wide isolator, the electrical gap and the creepage distance between the input end and the output end reach 15mm, the electrical gap and the creepage distance between the input end of the power supply module U4 and the output end reach 16mm, and the electrical gap and the creepage distance between the input end of the digital isolator U4 reach the basic requirements of 15mm when the input voltage of the digital isolator U7 exceeds the standard 6V 6-6102, the voltage signal reaches the basic requirements of the insulation circuit 21 mm, and the basic requirements of the insulation circuit III is met by the basic requirements of the digital isolator circuit 21, and the basic requirements of the voltage class III is met by the standard 15 mm.
The second isolation circuit 22 comprises a digital isolator U8 and a power supply module U5, an input side I/O port of the digital isolator U8 is connected with an output side I/O port of the digital isolator U7, an output side I/O port (CS, SCLK, MOSI, MISO) of the digital isolator U8 is connected with an SPI interface of the integrated circuit U3 in the direct-current electric energy metering circuit 1, an input power supply end of the power supply module U5 is provided by a DC5V power supply (+ 5V 1) output by the power supply module U4 in the first isolation circuit 21, a DC5V power supply (+ 5V 2) output by the power supply module U5 provides a DC5V working power supply for the output side power supply end of the digital isolator U8 and the integrated circuit U6 in the direct-current electric energy metering circuit 1, an electric gap of the isolation circuit 2 is 31mm, a creepage distance is 31mm, and when a DC 150V voltage signal is input according to a standard IEC61010-2-030, a double insulation electric gap of an overvoltage class III requirement is 19.4mm, and the creepage distance 30mm meets the double insulation requirement in the isolation circuit 2.
The MCU circuit 3 is used for reading voltage, current and electric energy parameters measured by the metering chip through the SPI port.
As shown in fig. 4, the MCU in the MCU circuit 3 receives and transmits data through the serial port and the communication circuit 4; and the voltage, the current and the electric energy of the metering chip are read through an SPI port, and a ninth integrated circuit U9 in the MCU circuit 3 is APM32F103CBT6.
The communication circuit 4 is used for externally providing an RS485 hardware interface to carry out data communication with the monitoring system, and the MCU circuit 3 is connected with the communication circuit 4 through a serial port.
As shown in fig. 5, the communication circuit 4 externally provides an RS485 hardware interface to perform data communication with the monitoring system, the pin 12 of the tenth integrated circuit U10 in the communication circuit 4 is connected in series with the first magnetic bead FB1 to connect with the a terminal of the RS485 interface a, the pin 12 of the tenth integrated circuit U10 is connected with the V485 power supply terminal through the third resistor R23 of the pull-up resistor, the pin 13 of the tenth integrated circuit U10 is connected in series with the second magnetic bead FB2 to connect with the terminal of the RS485 interface B, the pin 13 of the tenth integrated circuit U10 is connected with the G485 signal terminal through the second resistor R22 of the pull-down resistor, the pin 4 and the pin 5 of the tenth integrated circuit U10 are shorted and connected with the 3.3V power supply terminal through the first resistor R21 of the pull-up resistor, the collector of the first triode Q1 (NPN) is connected with the pin 4 and the pin 5 of the tenth integrated circuit U10, the base of the first triode Q1 is connected with the I/O (mcu_re) of the MCU in the MCU circuit 3 through the fourth resistor R24, the I/O control the state of the RS485 circuit is in the MCU circuit, when the pin 13 of the mcu_re is high level, the pin is in the state of the tenth integrated circuit is in the state of the receiving circuit 10, the tenth integrated circuit is in the receiving circuit is in the state of the MCU 3, and the pin is in the state of the receiving the signal receiving the pin 3 is in the MCU 3, and the pin 3 is in the state of the receiving the tenth integrated circuit is connected with the MCU 3. In order to improve electromagnetic compatibility of the RS485 circuit, two ends of a thirty-third safety capacitor C33 are respectively connected with a primary side pin 8 (GND signal end) and a secondary side pin 9 (G485 signal end) of a tenth integrated circuit U10, an RS485 interface A end and an RS485 interface B end are connected in parallel with a fourth TVS tube VD4, the RS485 interface A end is connected with a fifth TVS tube VD5 in parallel with the G485 signal end, and the RS485 interface B end is connected with a sixth TVS tube VD6 in parallel with the G485 signal end.
The power supply circuit 5 is a flyback switching power supply circuit, the input range supports DC 9V-36V, and the flyback switching power supply circuit is used for outputting two paths of isolated power supplies through a switching transformer and respectively providing working power supplies for the isolation circuit 2, the MCU circuit 3 and the communication circuit 4.
As shown in fig. 6, the power supply circuit 5 is a flyback switching power supply circuit, the input range supports DC 9V-36V, a first varistor RV1 in the power supply circuit 5 provides a first-stage overvoltage protection function, a third capacitor C3 and a first common-mode inductor L1 form an LC filter circuit, the first varistor RV1 and the third capacitor C3 are connected in parallel with the input end of the first common-mode inductor L1, one end of the output end of the first common-mode inductor L1 is electrically connected with the anode of the anti-reflection diode D1, and the other end is connected with the reference ground PGND of the power supply circuit; the cathode of the anti-diode D1 is connected with the positive end of the seventh electrolytic capacitor C7, the second bidirectional TVS tube VD2 provides second-stage overvoltage protection for the power supply circuit, two ends of the second bidirectional TVS tube VD2 are respectively connected with two ends of the seventh electrolytic capacitor C7 in parallel, the integrated circuit U2 is a flyback switching power supply chip to control the working state of the power supply circuit, a pin 5 of the integrated circuit U2 is connected with the positive end of the seventh electrolytic capacitor C7, a pin 5 is connected with the PGND end in parallel, a pin 1 of the integrated circuit U2 is connected with the positive end of the seventh electrolytic capacitor C7 through a ninth resistor R9, a pin 1 is connected with the PGND end through an eleventh resistor R11, a pin 2 of the integrated circuit U2 is connected with the PGND end, a pin 3 of the integrated circuit U2 is connected with a pin 4 of the integrated circuit U2 through a twelfth resistor R12, the cathode of the first unidirectional TVS tube VD1 and the cathode of the third diode D3 are connected in series to form a primary side absorption circuit of the switching transformer T1, the anode of the first unidirectional TVS tube 1 is connected with the pin 1 of the seventh electrolytic capacitor C7, and the anode of the integrated circuit U2 is connected with the positive end of the TVS 3 is connected with the pin 4 of the integrated circuit U2.
The switching transformer T1 outputs two groups of isolation power supplies, namely a DC5V working power supply +5V and a DC5V working power supply V485 are respectively provided for the isolation circuit 2, the MCU circuit 3 and the communication circuit 4, the anode of the fourth diode D4 is connected with the pin 6 of the switching transformer T1, the cathode of the fourth diode D4 is connected with the positive end of the eleventh electrolytic capacitor C11, the negative end of the eleventh electrolytic capacitor C11 is connected with the pin 5 of the switching transformer T1, the third inductor L3 and the ninth capacitor C9 form an LC filter circuit, the LC filter circuit outputs the DC5V power supply (+ 5V) to supply power to the MCU circuit 3, and the output end of the LC filter circuit is connected with the voltage stabilizing tube VD3 in parallel.
The anode of the second diode D2 is connected with the pin 10 of the first switching transformer T1, the second capacitor C2 and the fourth capacitor C4 form a parallel circuit, one end of the parallel circuit is connected with the cathode of the second diode D2 and the pin 1 and the pin 3 of the first integrated circuit U1, the other end of the parallel circuit is connected with the pin 9 of the first switching transformer T1 and the communication circuit ground signal end G485, the pin 2 of the first integrated circuit U1 is connected with the communication circuit ground signal end G485, and the pin 5 of the first integrated circuit U1 outputs DC5V power (V485) through the filtering of the fifth capacitor C5 to supply power to the communication circuit 4.
While specific embodiments of the utility model have been described above, it will be appreciated by those skilled in the art that these are by way of example only, and the scope of the utility model is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the principles and spirit of the utility model, but such changes and modifications fall within the scope of the utility model.
Claims (6)
1. The direct current electric energy meter circuit suitable for DC1500V voltage input is characterized by comprising a direct current electric energy metering circuit, an isolation circuit, an MCU circuit, a communication circuit and a power supply circuit;
the maximum value of the voltage of a direct current bus in the direct current electric energy metering circuit is DC1500V, bus current is sampled through a shunt, three input terminals U+ and I+ of the direct current electric energy metering circuit are sequentially connected with the positive voltage end U+ of the direct current bus of the electric equipment and output signals I+ and I-of the shunt, the output end of an isolation circuit is connected with an SPI port of a metering chip in the direct current electric energy metering circuit, the input end of the isolation circuit is connected with the SPI port of an MCU in the MCU circuit, the isolation circuit realizes SPI digital communication of the metering chip and the MCU, and the electric gap and creepage distance between the direct current electric energy metering circuit and the MCU circuit meet the double insulation requirement of DC1500V voltage input and overvoltage class III through the serial connection of a first isolation circuit and a second isolation circuit in the isolation circuit; the communication circuit is used for externally providing an RS485 hardware interface to perform data communication with the monitoring system, and the MCU circuit is connected with the communication circuit through a serial port; the power supply circuit is used for outputting two paths of isolated power supplies through the switching transformer, and is respectively connected with the isolation circuit, the MCU circuit and the communication circuit to provide working power supplies for the isolation circuit, the MCU circuit and the communication circuit.
2. The direct current electric energy meter circuit suitable for DC1500V voltage input as claimed in claim 1, wherein the voltage and current input signals in the direct current electric energy metering circuit are designed by three terminals, the voltage signal negative terminal U-and the current signal negative terminal I-are the same input terminal, the voltage signal negative terminal U-adopts a shunt output signal negative terminal I-as a common terminal of the voltage signal negative terminal U-and the current signal negative terminal I-, the positive terminal input U+ of DC1500V bus voltage is connected with a voltage channel of the metering chip after passing through a resistor divider circuit, wherein a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a seventh resistor R7 sequentially form a resistor divider circuit, one end of the resistor divider circuit is connected with the positive terminal input U+ of DC1500V bus voltage, the other end of the resistor divider circuit is connected with a reference ground signal GND2, a direct current bus voltage sampling signal on the seventh resistor R7 is connected with a positive terminal 8 of a third integrated circuit U3 voltage channel through a sixth resistor R6 and a filter circuit composed of a first capacitor C1, the positive terminal 8 of the third integrated circuit is connected with the voltage channel through a third resistor R2, and the negative terminal of the third resistor R2 is connected with the ground signal of the third integrated circuit is connected with the ground signal through a third resistor L2;
the DC bus current is sampled and output through the shunt to get mV signal to connect the current channel of the third integrated circuit U3, the positive end I+ of the output signal of the shunt connects one end of the fifth magnetic bead L5, thirteenth resistance R13, RC filter circuit that twelfth electric capacity C12 make up, one end of this RC filter circuit connects the other end of the fifth magnetic bead L5, another end of this RC filter circuit connects the positive end pin 4 of the current channel of the third integrated circuit U3, the negative end I-of the output signal of the shunt connects one end of the fourth magnetic bead L4, another end of the fourth magnetic bead L4 connects the ground signal GND2, the negative end pin 5 of the tenth electric capacity C10 of the tenth of the RC filter circuit, another end of this RC filter circuit connects the ground signal GND2 of the third integrated circuit U3, the negative end input U-of DC bus voltage is in short circuit with negative end I-of the output signal of the shunt, the sixth integrated circuit U6 provides 3.3V working power for the third integrated circuit U3, the sixth integrated circuit U6 is input by the DC output power supply of DC 5.
3. The direct current electric energy meter circuit suitable for DC1500V voltage input according to claim 1, wherein the isolating circuit is connected with an SPI port of a metering chip in the direct current electric energy metering circuit and an SPI port of an MCU in the MCU circuit through an SPI digital isolator, so that digital signal communication between the metering chip and the MCU is realized, and meanwhile, isolated DC5V working power supply input is provided for the direct current electric energy metering circuit;
the isolation circuit comprises a first isolation circuit and a second isolation circuit, wherein an input side I/O signal of the first isolation circuit is connected with an SPI port of the MCU, an output side I/O signal of the first isolation circuit is connected with an input side I/O signal of the second isolation circuit, an output side I/O signal of the second isolation circuit is connected with an SPI port of the metering chip, the two isolation circuits form a series circuit, and two stages of electric isolation between the SPI port of the metering chip and the MCU circuit are realized;
the first isolation circuit comprises a digital isolator U7 and a power supply module U4, wherein an input side I/O signal of the digital isolator U7 is connected with an SPI interface of the MCU circuit, an output side I/O signal of the digital isolator U7 is connected with an input side I/O signal of the second isolation circuit, an input power supply end of the power supply module U4 is provided with a DC5V power supply by the power supply circuit, an output DC5V power supply of the power supply module U4 supplies power to an output side power supply end of the digital isolator U7 and an input side power supply end of the second isolation circuit, the input side power supply end of the digital isolator U7 is provided by a 3.3V power supply in the MCU circuit, the digital isolator U7 is an ultra-wide isolator, the electric gap and the creepage distance between the input end and the output end of the digital isolator U7 reach 15mm, the electric gap and the creepage distance between the input end and the output end of the digital isolator U4 reach 16mm, and the basic insulation electric gap required by the overvoltage class III is 11mm when the input voltage signal of the digital isolator U7 and the power supply module U4 meet basic insulation requirements in a first module U4 standard according to standards 61010-2-030;
the second isolation circuit comprises a digital isolator U8 and a power supply module U5, an input side I/O port of the digital isolator U8 is connected with an output side I/O port of the digital isolator U7, an output side I/O port of the digital isolator U8 is connected with an SPI interface of an integrated circuit U3 in the direct-current electric energy metering circuit, an input power supply end of the power supply module U5 is provided by a DC5V power supply output by a power supply module U4 in the first isolation circuit, an output DC5V power supply of the power supply module U5 provides a DC5V working power supply for an output side power supply end of the digital isolator U8 and an integrated circuit U6 in the direct-current electric energy metering circuit, an electric gap of the isolation circuit is formed by connecting the first isolation circuit and the second isolation circuit in series, the creepage distance is 31mm, and when a direct-current electric energy metering circuit is input according to a standard IEC61010-2-030, the creepage distance is 19.4mm, the creepage distance is 30mm, and the isolation circuit meets the double insulation requirement in the standard.
4. The direct current electric energy meter circuit suitable for DC1500V voltage input as claimed in claim 1, wherein the MCU in the MCU circuit receives and transmits data through the serial port and the communication circuit; and the voltage, the current and the electric energy of the metering chip are read through an SPI port, and a ninth integrated circuit U9 in the MCU circuit is APM32F103CBT6.
5. The direct current electric energy meter circuit suitable for DC1500V voltage input as claimed in claim 1, wherein the communication circuit externally provides an RS485 hardware interface for data communication with the monitoring system, a pin 12 of a tenth integrated circuit U10 in the communication circuit is connected with an RS485 interface A end in series, a pin 12 of the tenth integrated circuit U10 is connected with a V485 power supply end through a pull-up resistor twenty-third resistor R23, a pin 13 of the tenth integrated circuit U10 is connected with a second magnetic bead FB2 in series and is connected with an RS485 interface B end, a pin 13 of the tenth integrated circuit U10 is connected with a G485 signal end through a pull-down resistor twenty-second resistor R22, a pin 4 and a pin 5 of the tenth integrated circuit U10 are in short circuit, the pin 4 and the pin 5 of the tenth integrated circuit U10 are connected through a pull-up resistor twenty-first resistor R21, a base electrode of the first triode Q1 is connected with I/O in MCU 3, the I/O controls the receiving state of the RS485 circuit, and when the I/O is in a state of the MCU 10 is in which the high-voltage integrated circuit U10 is connected with the MCU 3, and when the pin 10 is in a state of the MCU 6 is in a receiving state, the pin is connected with the MCU 3; in order to improve electromagnetic compatibility of the RS485 circuit, two ends of a thirty-third safety capacitor C33 are respectively connected with a primary side pin 8 and a secondary side pin 9 of a tenth integrated circuit U10, an RS485 interface A end and an RS485 interface B end are connected with a fourth TVS tube VD4 in parallel, an RS485 interface A end is connected with a fifth TVS tube VD5 in parallel to a G485 signal end, and an RS485 interface B end is connected with a sixth TVS tube VD6 in parallel to the G485 signal end.
6. The direct current electric energy meter circuit suitable for DC1500V voltage input as claimed in claim 1, wherein the power supply circuit is a flyback switching power supply circuit, the input range supports DC 9V-36V, a first voltage dependent resistor RV1 in the power supply circuit provides a first stage overvoltage protection function, a third capacitor C3 and a first common mode inductance L1 form an LC filter circuit, the first voltage dependent resistor RV1 and the third capacitor C3 are connected in parallel with the input end of the first common mode inductance L1, one end of the output end of the first common mode inductance L1 is electrically connected with the anode of a flyback preventing diode D1, and the other end is connected with the reference ground PGND of the power supply circuit; the cathode of the anti-reverse diode D1 is connected with the positive end of the seventh electrolytic capacitor C7, the second bidirectional TVS tube VD2 provides second-stage overvoltage protection for the power supply circuit, two ends of the second bidirectional TVS tube VD are respectively connected with two ends of the seventh electrolytic capacitor C7 in parallel, the integrated circuit U2 is a flyback switching power supply chip to control the working state of the power supply circuit, a pin 5 of the integrated circuit U2 is connected with the positive end of the seventh electrolytic capacitor C7, a pin 5 is connected with an eighth capacitor C8 in parallel to the PGND end, a pin 1 of the integrated circuit U2 is connected with the positive end of the seventh electrolytic capacitor C7 through a ninth resistor R9, a pin 1 is connected with the PGND end through an eleventh resistor R11, a pin 2 of the integrated circuit U2 is connected with the PGND end, a pin 3 of the integrated circuit U2 is connected with a pin 4 of the integrated circuit U2 through a twelfth resistor R12, the cathode of the first unidirectional TVS tube VD1 and the cathode of the third diode D3 are connected in series to form a primary side absorption circuit of the switching transformer T1, the anode of the first unidirectional TVS tube 1 is connected with the pin 1 of the anode of the switching transformer T7 and the positive end of the seventh electrolytic capacitor C7, and the pin 2 of the integrated circuit U2 is connected with the TVS 2;
the switching transformer T1 outputs two groups of isolation power supplies, namely an isolation circuit, an MCU circuit and a communication circuit are respectively provided with a DC5V working power supply +5V, the anode of the fourth diode D4 is connected with the pin 6 of the switching transformer T1, the cathode of the fourth diode D4 is connected with the positive end of the eleventh electrolytic capacitor C11, the negative end of the eleventh electrolytic capacitor C11 is connected with the pin 5 of the switching transformer T1, the third inductor L3 and the ninth capacitor C9 form an LC filter circuit, the LC filter circuit outputs a DC5V power supply to supply power to the MCU circuit, and the output end of the LC filter circuit is connected with a voltage stabilizing tube VD3 in parallel;
the anode of the second diode D2 is connected with the pin 10 of the first switching transformer T1, the second capacitor C2 and the fourth capacitor C4 form a parallel circuit, one end of the parallel circuit is connected with the cathode of the second diode D2 and the pin 1 and the pin 3 of the first integrated circuit U1, the other end of the parallel circuit is connected with the pin 9 of the first switching transformer T1 and the communication circuit ground signal end G485, the pin 2 of the first integrated circuit U1 is connected with the communication circuit ground signal end G485, and the pin 5 of the first integrated circuit U1 outputs DC5V power through the filtering of the fifth capacitor C5 to supply power to the communication circuit.
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| CN202320679976.0U CN219496521U (en) | 2023-03-31 | 2023-03-31 | Direct current electric energy meter circuit suitable for DC1500V voltage input |
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| CN202320679976.0U CN219496521U (en) | 2023-03-31 | 2023-03-31 | Direct current electric energy meter circuit suitable for DC1500V voltage input |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116338304A (en) * | 2023-03-31 | 2023-06-27 | 江苏斯菲尔电气股份有限公司 | Electric energy meter circuit suitable for DC1500V voltage input |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116338304A (en) * | 2023-03-31 | 2023-06-27 | 江苏斯菲尔电气股份有限公司 | Electric energy meter circuit suitable for DC1500V voltage input |
| CN116338304B (en) * | 2023-03-31 | 2024-06-11 | 江苏斯菲尔电气股份有限公司 | Electric energy meter circuit suitable for DC1500V voltage input |
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