CN203689052U

CN203689052U - Power and relay driving circuit for electric energy meter equipped with communication module

Info

Publication number: CN203689052U
Application number: CN201320734928.3U
Authority: CN
Inventors: 吴浩
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-11-20
Filing date: 2013-11-20
Publication date: 2014-07-02
Anticipated expiration: 2023-11-20

Abstract

The utility model discloses a power and relay driving circuit for an electric energy meter equipped with a communication module. The power and relay driving circuit comprises a power transformer, a full-wave rectification circuit, a half-wave rectification circuit, a metering front end, a MCU, a SOC, optically-coupled isolation circuits, a RS485 circuit, a communication module circuit, a relay driving input circuit, and a relay driving output circuit. The relay driving output circuit and the communication module circuit, which consume large power in the electric energy meter, share the output of one heavy-load winding of the power transformer. 4000V electrical isolation is arranged between the heavy-load winding and a heavy-current primary side. The relay driving circuit and the communication module are controlled by the MCU to be used at different time such that requirements for cost and volume of the power transformer can be reduced. Optically-coupled isolation circuits are achieved between the relay driving output circuit and the central processor MCU, and between the communication module circuit and the central processor MCU. The power and relay driving circuit is suitable for SOC schemes and schemes in which the metering front end and the MCU are separated.

Description

A kind of for the power supply with communication module electric energy meter and relay drive circuit

Technical field

The utility model relates to electric energy meter circuit line design, mainly relate to drive with communication module and relay and this communication module and forceful electric power between have 4000V electrical isolation to require electric energy meter.

Background technology

Between the communication module of 2013 editions State Grid Corporation of China's requirement electric energy meters and auxiliary terminal and forceful electric power, there is 4000V electrical isolation with protection personal safety, roughly there is at present two schemes: the first is the separation scheme that adopts metering front end and MCU to divide out, the electrical isolation of this separation scheme is between metering front end and MCU, the shortcoming of this scheme is: MCU is directly connected with communication module, centre does not have electrical isolation, in the time that communication module is subject to external interference, MCU is also interfered simultaneously, and MCU is the core of electric energy meter, once be interfered, electric energy meter just easily breaks down.This scheme has also limited the application of SOC chip in electric energy meter simultaneously, and SOC electric energy meter scheme has the features such as cost is low, data are reliable.This scheme also have a shortcoming be when communication module be that carrier module and electric energy meter cause not reaching the requirement of 4000V electrical isolation between IC-card interface and forceful electric power during also with IC-card interface because stipulate in carrier module technical conditions that the electrical isolation intensity between its forceful electric power and light current is 2500V.The second is that designing power supply transformer has two groups of heavy load winding outputs, these two groups of heavy load winding outputs all have 4000V electrical isolation with the former limit of forceful electric power, one group of output shares for measuring front end and MCU and relay drive circuit, another group output shares for communication module and RS485 circuit, the shortcoming of this scheme is: due to two groups of heavy load winding outputs of needs, increased cost and the volume of power transformer.Equally also cause the requirement that the electrical isolation intensity between forceful electric power and RS485 light current terminal does not reach 4000V in the time that communication module is carrier module, because stipulate in carrier module technical conditions that the electrical isolation intensity between its forceful electric power and light current is 2500V.

Summary of the invention

For prior art defect, the technical problems to be solved in the utility model is exactly to design a kind of new power circuit and relay drive circuit, make this circuit both be applicable to SOC scheme, be applicable to again to measure the separation scheme that front end and MCU divide out, also will guarantee has 4000V electrical isolation between communication module and forceful electric power, do not increase power transformer cost and volume, yet ensure and in the time that communication module is carrier module, do not reduce the desired 4000V electrical isolation of electric energy meter intensity simultaneously simultaneously.

Described in the utility model a kind of for the power supply with communication module electric energy meter and relay drive circuit, comprising: have the power transformer of three groups of outputs, wherein one group is the self coupling output of former limit, and load capacity is less than or equal to 50mA; Another two groups is isolation output, and one group is heavy load output, and load capacity is greater than 100mA, and another group is weak load output, and load capacity is less than or equal to 30mA; Also comprise that relay drives input circuit, relay driver output circuit and the optical coupling isolation circuit between this imput output circuit; Also comprise optical coupling isolation circuit and metering front end and MCU, SOC, RS485 circuit, full-wave rectifying circuit, half-wave rectifying circuit and relay between optical coupling isolation circuit, RS485 and the MCU between communication module digital signal light current interface and MCU.

Principle of work of the present utility model is as described below: the self coupling winding output that is less than or equal to 50mA is powered for measuring front end and MCU or SOC after half-wave rectification and voltage stabilizer; The isolated windings output that is less than or equal to 30mA supplies RS485 circuit supply after half-wave rectification and voltage stabilizer; The isolated windings output that is greater than 100mA supplies communication module circuit and relay driver output circuit supply after full-wave rectification and after voltage stabilizer.MCU or SOC are by reaching signal exchange and have 4000V electrical isolation intensity between light-coupled isolation and RS485 circuit, communication module circuit, relay driver output circuit; Because communication module all produces larger electric current in the time sending state and when relay drive circuit drives the actuating of relay, drive this two parts circuit therefore control timesharing by MCU or SOC.

Accompanying drawing explanation

Fig. 1 is theory diagram of the present utility model;

Fig. 2 is power circuit and optical coupling isolation circuit schematic diagram;

Fig. 3 is SOC circuit diagram.

Embodiment

Take SOC scheme as example, with reference to accompanying drawing 2, forceful electric power 220V is from power transformer T1 former limit input, and the raw three groups of power supplys of common property are exported, 2,3 windings of T1 are the self coupling output that load capacity is less than or equal to 50mA, are used for to SOC U20 circuit supply through diode D5 half-wave rectification and U6 voltage stabilizing; 4,5 windings of T1 are the isolation output that load capacity is less than or equal to 30mA, are used for to RS485 circuit supply through diode D6 half-wave rectification and U8 voltage stabilizing; 6,7 windings of T1 are the isolation output that load capacity is greater than 100mA, after rectistack U12 full-wave rectification and U11 voltage stabilizing for giving communication module circuit and relay driver output circuit supply.

With reference to accompanying drawing 2 and accompanying drawing 3, the IO pin 21 ~ 24 of SOC U20 and pin 41 ~ 42 consist of the communication interface of isolation optocoupler U14 ~ U19 and carrier communication module circuit; Realize relay driving isolation by optocoupler U1 and U2 and relay driver output circuit triode Q1, Q2, Q3, Q4 and resistance R 2, R3, R5, R6, it is resistance R 1 and R4 that relay drives input circuit; Realize communication and control function by optocoupler U9, U10 and RS485 circuit.

In order to reduce the requirement of 6, the 7 winding output currents to power transformer T1, use relay to drive and carrier wave transmission by SOC software program control timesharing.

Claims

1. for the power supply with communication module electric energy meter and a relay drive circuit, comprise that power transformer, relay drive input circuit, relay driver output circuit, communication module circuit, full-wave rectifying circuit, half-wave rectifying circuit, metering front end and MCU, SOC, optical coupling isolation circuit, RS485 circuit, relay.It is characterized in that, power transformer has three winding outputs, and wherein the output of maximum load capability winding has 4000V electrical isolation with the former limit of forceful electric power, and this maximum load capability winding output is for relay driver output circuit and communication module circuit supply.

2. according to claim 1ly a kind ofly it is characterized in that all there is light-coupled isolation between relay driver output circuit and communication module circuit and SOC for the power supply with communication module electric energy meter and relay drive circuit.