Power-down communication device capable of automatically adapting to power supply of electric energy meter

Abstract

The utility model discloses a power failure communication device capable of automatically adapting to a power supply of an electric energy meter, which comprises an interface circuit, a second pin and a third pin of the interface circuit are connected with a signal conversion circuit, the signal conversion circuit comprises a chip U1, the chip U1 is connected with a triode Q2, a sixth pin of the interface circuit is connected with a step-down circuit, and the step-down circuit is connected with a system power supply. And a pin 7 of the interface circuit is connected with the 12V power supply circuit through the booster circuit. In order to solve the problems that an existing MC171 tool is narrow in application range and cannot meet the use requirement of a common electric meter at the same time, the power failure communication device is simple in structure, contact connection can be achieved according to an MC171 interface on the electric energy meter, and the power failure communication device can generate matched power and signal levels according to a power system of the electric meter. And the function of normally reading data such as electric quantity, demand and event records in the meter is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of electric energy meters, in particular to a power-off communication device capable of automatically adapting to the power supply of an electric energy meter. Background Art

[0002] Existing electricity meters are maliciously damaged by external forces during use, causing the power supply system of the meter to be damaged. Even if the meter is connected to the mains, the electricity meter cannot work normally. At this time, the power bureau cannot read the electricity usage recorded in the meter and cannot reach an agreement with the customer on the electricity bill.

[0003] In extreme cases, the meter's power supply system suddenly becomes abnormal during long-term use due to its own power supply design defects (circuit design and material problems). Even if the meter is connected to the mains, the meter cannot start working. If the meter is not started normally, the event record and meter power information cannot be obtained through the meter's near infrared or carrier or 485 or MBUS communication methods. The existing MC171 tool can only read the meter data of the 3.3V power supply system, while a large number of meters used on the market have both 5V power supply systems and 3.3V power supply systems. When the existing MC171 tool reads the meter of the 5V power supply system, the communication is not available.

[0004] Public announcement number: CN218099572U, public announcement date: 2022-12-20 It involves a power-off communication device and system for an electric energy meter. The device is applied to the electric energy meter, and the MCU of the electric energy meter is connected to the MC171 interface of the electric energy meter; the device includes: a signal conversion circuit, a boost circuit and a buck circuit; the signal conversion circuit is respectively connected to the MC171 interface and the USB interface of the host computer; the boost circuit is respectively connected to the MC171 interface and the USB interface; the buck circuit is respectively connected to the MC171 interface and the USB interface. This solution can only be applied to the case of a 3.3V system power supply, but cannot be applied to the case of a 5V system power supply. Utility Model Content

[0005] The utility model aims to solve the problem that the existing MC171 tooling has a narrow application range and cannot meet the needs of common electric meters at the same time, and provides a power-off communication device that can automatically adapt to the power supply of the electric energy meter.

[0006] In order to achieve the above-mentioned purpose, the solution provided by the utility model is: a power-off communication device that can automatically adapt to the power supply of an electric energy meter, including: an interface circuit, pins 2 and 3 of the interface circuit are connected to a signal conversion circuit, the signal conversion circuit includes a chip U1, and the chip U1 is connected to a transistor Q2, pin 6 of the interface circuit is connected to a step-down circuit, the step-down circuit is connected to a system power supply, and pin 7 of the interface circuit is connected to a 12V power supply circuit through a step-up circuit.

[0007] Preferably, the chip U1 includes a data pin and two UART signal pins; the two UART signal pins are respectively connected to pins 2 and 3 of the interface circuit.

[0008] Preferably, the emitter of the transistor Q2 is connected to the UART signal pin connected to pin 2 of the interface circuit, and the collector of the transistor Q2 is connected to pin 2 of the interface circuit.

[0009] Preferably, pin 3 of the interface circuit is connected to the cathode of the diode D25, and the anode of the diode D25 is connected to the UART signal pin connected to pin 3 of the interface circuit.

[0010] Preferably, the step-down circuit includes a chip U2; the chip U2 includes a second voltage input pin and a second voltage output pin; the second voltage input pin is connected to the system power supply; and the voltage output pin is connected to pin 6 of the interface circuit.

[0011] Preferably, the boost circuit includes a chip U3; the chip U3 includes a first voltage input pin and a first voltage output pin; the first voltage input pin is connected to the 12V power supply circuit; and the first voltage output pin is connected to pin 7 of the interface circuit.

[0012] Preferably, the interface circuit further includes a resistor R6, the resistor R6 is connected to pin 4 of the interface circuit, and the resistor R6 is connected to the second voltage output pin.

[0013] The beneficial effect of the utility model is that it solves the problem that the existing MC171 tooling has a narrow application range and cannot meet the needs of commonly used electric meters at the same time. No matter whether the power supply system of the electric meter is 5V or 3.3V, as long as the USB end of the MC171 tooling is connected to the computer and the other end is contact-connected with the MC171 interface on the electric energy meter, the MC171 tooling will generate matching power and signal levels according to the power supply system of the electric meter itself, and realize the function of normally reading data such as the power quantity, demand quantity, and event records in the meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a connection diagram of the utility model.

[0015] Figure 2 It is a circuit diagram of the interface circuit of the utility model.

[0016] Figure 3 The utility model is a circuit diagram of a signal conversion circuit.

[0017] Figure 4 The utility model is a circuit diagram of a signal conversion circuit.

[0018] Figure 5 The utility model is a circuit diagram of a signal conversion circuit.

[0019] Figure 6 The utility model is a circuit diagram of a signal conversion circuit.

[0020] Figure 7 The utility model is a circuit diagram of a step-down circuit.

[0021] Figure 8 It is a circuit diagram of the boost circuit of the utility model.

[0022] Fig. 9 It is a signal simulation diagram of the utility model. DETAILED DESCRIPTION

[0023] The specific embodiments of the utility model will be described in detail below. It should be noted that the embodiments described here are only part of the embodiments of the utility model, not all of them. Based on the following embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] The utility model provides the following technical solutions:

[0025] like Figure 1 As shown, a power-off communication device that can automatically adapt to the power supply of an electric energy meter includes: an interface circuit, pins 2 and 3 of the interface circuit are connected to a signal conversion circuit, the signal conversion circuit includes a chip U1, the chip U1 is connected to a transistor Q2, pin 6 of the interface circuit is connected to a step-down circuit, the step-down circuit is connected to a system power supply, and pin 7 of the interface circuit is connected to a 12V power supply circuit through a step-up circuit.

[0026] like Figure 2 As shown, the interface circuit is con8 chip interface, and the 1st pin of the interface circuit is reserved. This tooling is designed as a power interface; the 2nd pin of the interface circuit is a data transmission interface, and the 3rd pin of the interface circuit is a data receiving port. The communication mode of the 2nd and 3rd pins is defined as UART communication mode. This utility model is specially designed for pins 2 and 3; the 4th pin of the interface circuit is a power state detection port, that is, after the MC171 tooling is contact-connected with the interface circuit, the tooling provides a high level for the meter. At this time, the meter determines that the power supply is normally powered on, and MC171 reads the data in the meter normally; the 5th pin of the interface circuit is grounded; the 6th pin of the interface circuit is a power interface, 5V or 3.3V, and this utility model is designed for this pin; the 7th pin of the interface circuit is connected to a +12V power supply. After the meter is contact-connected with the MC171 tooling, this power supply is provided by the MC171 tooling.

[0027] like Figure 3 , 4As shown in Figures 5 and 6, the signal conversion circuit uses the CP2102 chip U1. U1 includes pins 0 to 28. Pins 4 and 5 of U1 are data pins D+ and D-, respectively. Pins 25 and 26 of U1 are UART signal pins TXD and RXD, respectively. Pin 25 of U1 is connected to the data sending pin of the energy meter MC171 interface through resistor R5, and pin 26 of U1 is connected to the data receiving pin of the energy meter MC171 interface through resistor R4. Figure 3 , 4 The circuit structures shown in , 5 and 6 can convert the USB signal of the host computer into a UART signal, and realize the UART signal interaction between the above-mentioned power-off communication device of the electric energy meter and the electric energy meter.

[0028] The existing MC171 tooling has pins 2 and 3 that are directly connected to the signal transceiver circuit at the meter end, and the meter end receiving signal has a 10K pull-up (meter default), and the MC171 end transceiver signal has a 3.3V pull-up. When the meter end system power DVDD is 3.3V, the existing MC171 tooling design is fine, but when the meter end system power is 5V, the power pull-up will cause data interaction failure. The circuit designed by this utility model realizes data interaction with the MC171 tooling regardless of whether the meter end system power is 3.3V or 5V.

[0029] The MC171 tooling provides a voltage of about +12V for pin 7 of the MC171 interface of the meter through DC-DC boost voltage. Pin 7 of the MC171 interface of the meter and the +12V AC-DC output network of the meter end are connected together by default. If the system power supply of the meter end is 5V, 5V power supply can be output through the DC-DC or LDO circuit conversion of the meter end. At this time, even if pin 6 of the MC171 tooling has provided 3.3V voltage for the meter, due to power competition, the system power supply of the meter end is 5V.

[0030] The meter can automatically convert the 12V power supply into the system 3.3V or 5V, but because the MC171 interface explicitly requires that pin 6 is the DVDD power input, an LDO circuit is also required to convert the 5V power supply input from the USB into 3.3V. Some meters have a 3.3V system power supply. If the MC171 tooling directly provides a 5V power supply to the meter system, the chip or peripheral devices of the meter may be damaged. The operating voltage range of the commonly used FLASH chip is 2.7V to 3.6V. If the MC171 tooling provides a 5V system voltage to the meter through pin 6, the FLASH chip at the meter end will be burned.

[0031] The signal conversion circuit includes a data receiving circuit and a data sending circuit. In the data receiving circuit, the emitter of the transistor Q2 is connected to the UART signal pin connected to the 2nd pin of the interface circuit, the collector of the transistor Q2 is connected to the 2nd pin of the interface circuit, the base of the transistor Q2 is connected to the system power supply through the resistor R8, and the emitter of the transistor Q2 is connected to the system power supply through the resistor R4. In the data receiving circuit, the cathode of the diode D25 is connected to the 3rd pin of the interface circuit, the anode of the diode D25 is connected to the UART signal pin connected to the 3rd pin of the interface circuit through the resistor R28 and is connected to the system power supply through the resistor R29. Figure 5 In the figure, R9 does not actually exist in the MC171 tooling. For meters with MC171 communication function, this pin has a 10K resistor pulled up to the system power supply. When the data interaction between the MC171 tooling and the meter is initiated by the tooling, when there is no communication, IR_TXD is high level (3.3V) and METER_RXD is high level (3.3V or 5V). When the communication between the MC171 tooling and the meter is initiated, IR_TXD is low and effective, Q2 is turned on, and METER_RXD follows IR_TXD to a low level. When the meter's METER_TXD outputs a low level, D25 is forward-conducted, and IR_RXD is pulled down to a low level accordingly. The level situation is as follows: Fig. 9 shown.

[0032] like Figure 7 As shown, the boost circuit adopts SGM6607 chip V2, V2 includes pins 1 to 6, pin 1 of V2 is the first voltage input pin Vin, and pin 6 of V2 is the first voltage output pin fb; the USB interface of the host computer includes pins 1 to 4, pin 1 VBUS of the USB interface is connected to pin 1 Vin of V2, and pin 6 of V2 is connected to the +12V pin of the power meter MC171 interface through resistors R12 and R13.

[0033] When the energy meter loses power, a DCDC boost circuit is formed by devices V2, L6, D7, R12, R13, R10, C7, R11, R14 and C8. The DCDC boost circuit raises the 5V voltage to +12V, and the power supply VCC_+12V is provided to pin 7 of the MC171 interface of the energy meter, thereby providing a +12V power supply voltage for the energy meter to ensure the normal operation of the energy meter.

[0034] The DC-DC boost circuit converts the 5V voltage obtained by the MC171 tool from the computer USB port VBUS into the output of VCC_+12V through V2, SGM6607 and peripheral circuits. The output voltage is 13.9V. The specific calculation formula is as follows:

[0035] Output voltage:

[0036] VCC_+12V=V_FB / R10×(R10+R12+R13)=1.21V / 20K×(10K+200K+20K)=13.9V

[0037] The maximum output of a desktop USB port is 500mA, and the maximum output of a laptop USB port is 100mA.

[0038] MC171 tooling connected to a desktop computer, maximum output current:

[0039] I_(VCC_+12V)=(5V×500mA×0.8) / 13.9≈144mA

[0040] MC171 tooling connected to a laptop, maximum output current:

[0041] I_(VCC_+12V)=(5V×100mA×0.8) / 13.9≈30mA.

[0042] like Figure 8 As shown, the step-down circuit 103 includes a second voltage input pin and a second voltage output pin; the second voltage input pin is connected to the first power pin of the USB interface 301; the voltage output pin is connected to the third power pin of the MC171 interface 202, and the power voltage corresponding to the third power pin is less than the power voltage corresponding to the second power pin. The power voltage corresponding to the third power pin is 3.3V, and the power voltage corresponding to the second power pin is 12V. The specific selection of the step-down chip can be selected according to actual needs, and there is no limitation on this.

[0043] The step-down circuit adopts LDO chip U2, U2 includes pins 0 to 3, pin 3 of U2 is the second voltage input pin Vin, and pin 1 of U2 is the second voltage output pin Vout; the USB interface of the host computer includes pins 1 to 4, pin 1 VBUS of the USB interface is connected to pin 3 Vin of U2, and pin 1 Vout of U2 is connected to the system power pin of the power meter MC171 interface through diode D8.

[0044] When the energy meter loses power, an LDO step-down circuit is formed by devices U2, D8, C5, C4, and C3. The 5V voltage output by pin 5 VBUS of the USB interface of the host computer is connected to pin 3 Vin of U2. The LDO step-down circuit converts the 5V voltage into a +3.3V power supply and provides it to pin 6 of the MC171 interface of the energy meter, thereby providing a +3.3V power supply voltage for the energy meter to ensure the normal operation of the MCU of the energy meter; device C4 is a filter capacitor for the input voltage VBUS; devices C3 and C5 are filter capacitors for the output voltage +3.3V; device D8 is a Schottky diode, which can prevent current kickback from damaging U2.

[0045] Through LDO chip U2, the 5V power supply of USB interface is converted into system power supply 3.3V. According to SGM2203-3.3YK3G / TR, the relative voltage of U2 pin 1 VOUT to U2 pin 2 GND is 3.3V. Resistors R15, R16, and R17 form a voltage divider circuit to raise the output pin 1 VOUT of U2 to 3.63V relative to the system ground GND. The specific calculation method is: VOUT = 3.3V / 20K (1K + 1K + 20K) = 3.63V, and D8 plays an anti-reverse role. The forward conduction voltage drop of D8 is about 0.2V-0.3V. In order for MC171 tooling to output a stable 3.3V voltage to the meter, R15, R16, and R17 exist.

[0046] Based on the above embodiments, the present application proposes a power-off communication device that can automatically adapt to the power supply of an electric energy meter. It adopts a specially designed signal conversion circuit. Regardless of whether the power supply system of the electric energy meter is 5V or 3.3V, as long as the power bureau connects the USB end of this MC171 tool to the computer and the other end to the MC171 interface on the electric energy meter by contact, this MC171 tool will generate matching power and signal levels according to the power supply system of the electric energy meter itself, thereby realizing the function of normally reading the data such as the power quantity, demand quantity, and event records in the meter.

[0047] The above shows and describes the basic features, principles and advantages of the utility model. It should be noted that the utility model is not limited to the above embodiments, which are only partial embodiments. Under the premise of not departing from the spirit and scope of the utility model, several improvements and supplements made are deemed to be within the protection scope of the utility model.

Claims

1. A power-off communication device capable of automatically adapting to the power supply of an electric energy meter, characterized in that: include: An interface circuit, wherein pins 2 and 3 of the interface circuit are connected to a signal conversion circuit, wherein the signal conversion circuit comprises a chip U1, wherein the chip U1 is connected to a transistor Q2, wherein pin 6 of the interface circuit is connected to a step-down circuit, wherein the step-down circuit is connected to a system power supply, and wherein pin 7 of the interface circuit is connected to a 12V power supply via a step-up circuit.

2. According to the power-off communication device capable of automatically adapting to the power supply of an electric energy meter as described in claim 1, the chip U1 comprises a data pin and two UART signal pins; the two UART signal pins are respectively connected to pins 2 and 3 of the interface circuit.

3. According to the power-off communication device that can automatically adapt to the power supply of the electric energy meter as described in claim 2, the emitter of the transistor Q2 is connected to the UART signal pin connected to the 2nd pin of the interface circuit, and the collector of the transistor Q2 is connected to the 2nd pin of the interface circuit.

4. According to the power-off communication device capable of automatically adapting to the power supply of the electric energy meter as described in claim 3, pin 3 of the interface circuit is connected to the cathode of the diode D25, and the anode of the diode D25 is connected to the UART signal pin connected to pin 3 of the interface circuit.

5. According to a power-off communication device that can automatically adapt to the power supply of an electric energy meter according to any one of claims 1 to 4, the step-down circuit includes a chip U2; the chip U2 includes a second voltage input pin and a second voltage output pin; the second voltage input pin is connected to the system power supply; the voltage output pin is connected to pin 6 of the interface circuit.

6. According to a power-off communication device that can automatically adapt to the power supply of an electric energy meter according to any one of claims 1 to 4, the boost circuit includes a chip U3; the chip U3 includes a first voltage input pin and a first voltage output pin; the first voltage input pin is connected to the 12V power supply; the first voltage output pin is connected to pin 7 of the interface circuit.

7. According to the power-off communication device capable of automatically adapting to the power supply of the electric energy meter as described in claim 5, the interface circuit further comprises a resistor R6, the resistor R6 is connected to pin 4 of the interface circuit, and the resistor R6 is connected to the second voltage output pin.

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