CN218917502U

CN218917502U - Super-high isolation voltage-resistant low-speed communication isolation circuit for intelligent electric meter

Info

Publication number: CN218917502U
Application number: CN202223012481.7U
Authority: CN
Inventors: 张炯; 刘鑫禹
Original assignee: Qingdao iTechene Technologies Co ltd
Current assignee: Qingdao iTechene Technologies Co ltd
Priority date: 2022-11-11
Filing date: 2022-11-11
Publication date: 2023-04-25
Anticipated expiration: 2032-11-11

Abstract

The utility model discloses an ultrahigh isolation voltage-resistant low-speed communication isolation circuit for an intelligent ammeter, which comprises a primary isolation circuit and a secondary isolation circuit, wherein the primary isolation circuit is connected with the secondary isolation circuit; the primary isolation circuit is respectively connected with the MCU signal transmitting end and the MCU signal receiving end and comprises an optocoupler DC1, an optocoupler DC3, a resistor RC1, a resistor RC2, a resistor RC5 and a resistor RC6; the secondary isolation circuit is respectively connected with a signal transmitting end and a signal receiving end of the communication chip and comprises an optocoupler DC2, an optocoupler DC4, a resistor RC3, a resistor RC4, a resistor RC7 and a resistor RC8; the utility model uses a plurality of optocouplers to carry out multistage isolation, the voltage withstand and anti-interference effect are obviously improved compared with the traditional isolation circuit, and the minimum alternating current voltage withstand value is 8KV; the circuit is simple, the cost is low, the sensitivity is high, and the adaptability and the practicability are very strong.

Description

Super-high isolation voltage-resistant low-speed communication isolation circuit for intelligent electric meter

Technical Field

The utility model relates to the technical field of intelligent ammeter communication, in particular to an ultra-high isolation voltage-resistant low-speed communication isolation circuit for an intelligent ammeter.

Background

Because the environmental condition of smart electric meter equipment use scene is comparatively complicated, when the remote communication that carries out, often accompanies interference such as ground loop, transient voltage in the signal transmission process, therefore need carry out interference suppression to communication signal, simultaneously to signal isolation effect such as 485 communication, 232 communication be one of the important indexes of judging product reliability always.

In the process of designing intelligent ammeter equipment, if the requirement on isolation withstand voltage is high, devices such as high speed Rong Ou are usually used, but the price of the devices is relatively high, and the cost of ammeter products is increased intangibly.

Disclosure of Invention

In order to solve the problems, the utility model provides an ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart electric meter.

The utility model adopts the scheme that: an ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart electric meter comprises a primary isolation circuit and a secondary isolation circuit;

the primary isolation circuit comprises an optocoupler DC1, an optocoupler DC3, a resistor RC1, a resistor RC2, a resistor RC5 and a resistor RC6; the cathode of the photodiode in the optocoupler DC3 is connected to the MCU signal transmitting end, and the anode is connected to a main system power supply through a resistor RC 5; the emitter of the internal triode of the optocoupler DC3 is connected to auxiliary reference ground, the collector is connected to the cathode of the photodiode in the secondary isolation circuit DC4, and the collector is connected to an isolated auxiliary power supply through a resistor RC6; the collector of the triode in the optical coupler DC1 is connected to the MCU signal receiving end, and is connected to a main system power supply through a resistor RC1, and the emitter is connected to the main system ground; the cathode of the photodiode in the optocoupler DC1 is connected to the collector of the triode in the optocoupler DC2 in the secondary isolation circuit, and the anode of the photodiode is connected to the isolation auxiliary power supply through RC 2;

the secondary isolation circuit comprises an optocoupler DC2, an optocoupler DC4, a resistor RC3, a resistor RC4, a resistor RC7 and a resistor RC8; the cathode of the photodiode in the optical coupler DC2 is connected to the signal transmitting end of the communication chip, and the anode of the photodiode is connected to a communication power supply through a resistor RC 4; the emitter of the internal triode of the optocoupler DC2 is connected to auxiliary reference ground, the collector is connected to the anode of the internal photodiode of the optocoupler DC1 in the primary isolation circuit, and the collector is connected to an isolated auxiliary power supply through a resistor RC 3; the collector electrode of the triode in the optical coupler DC4 is connected to the signal receiving end of the communication chip, and is connected to a communication power supply through a resistor RC8, and the emitter electrode of the triode is connected to a communication reference ground; and the anode of the photodiode in the optocoupler DC4 is connected to an isolation auxiliary power supply through a resistor RC7, and the cathode of the photodiode is connected to the collector of the triode in the optocoupler DC3 in the primary isolation circuit.

Preferably, the optocouplers DC1, DC2, DC3 and DC4 are optoisolators, the current transmission ratio CTR is more than 300%, and the forward current is 50mA.

Preferably, the resistor RC1, the resistor RC3, the resistor RC5 and the resistor RC7 are chip ceramic resistors, and the resistance is 820 Ω.

Preferably, the resistor RC2 and the resistor RC4 are chip ceramic resistors, and the resistance is 1.5kΩ.

Preferably, the resistor RC6 and the resistor RC8 are chip resistors, and the resistance is 1kΩ.

Compared with the prior art, the utility model has the following beneficial effects: the multi-stage isolation is carried out by using a plurality of optocouplers, compared with the traditional isolation circuit, the voltage withstand and anti-interference effect are obviously improved, and the minimum alternating current voltage withstand value is 8KV; the circuit is simple, the cost is low, the sensitivity is high, and the adaptability and the practicability are very strong.

Drawings

Fig. 1 is a schematic circuit structure of the present utility model.

Detailed Description

The present utility model will be further described with reference to specific examples.

As shown in FIG. 1, the utility model provides an ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart electric meter, which utilizes a plurality of optocouplers to carry out multistage isolation so as to achieve an isolation device (alternating current is more than 8 KV) for realizing the ultra-high isolation voltage-resistant.

The isolation device comprises a first-stage isolation circuit and a second-stage isolation circuit. The primary isolation circuit comprises optocouplers DC1 and DC3, and resistors RC1, RC2, RC5 and RC6; the secondary isolation circuit comprises optocouplers DC2 and DC4, and resistors RC3, RC4, RC7 and RC8.

In the primary isolation circuit, an MCU (micro control Unit) sends a signal M_RS_TXD to be connected to the cathode of an internal photodiode of an optocoupler DC3, the anode of the photodiode is connected to a main system power supply DVDD through a resistor RC5, the emitter of an internal triode of the optocoupler DC3 is connected to a reference ground SGND, and the collector of the internal triode is connected to a signal end S_RS_TXD and is connected to the power supply SVDD through a resistor RC6; the signal terminal S_RS_RXD is connected to the cathode of the photodiode inside the optocoupler DC1, the anode of the photodiode is connected to the auxiliary isolation power supply SVDD through a resistor RC2, the emitter of the triode inside the optocoupler DC1 is connected to the main system reference ground GND, and the collector is connected to the signal terminal M_RS_RXD and is connected to the main system power supply DVDD through the resistor RC 1.

In the secondary isolation circuit, a communication chip sends a signal RS_TXD to be connected to the cathode of an internal photodiode of an optocoupler DC2, the anode of the photodiode is connected to a communication power supply R+5V through a resistor RC4, the emitter of an internal triode of the optocoupler DC2 is connected to a reference ground SGND, the collector is connected to a signal end S_RS_RXD, and the collector is connected to a power supply SVDD through a resistor RC 3; the signal terminal S_RS_RXD is connected to the cathode of the photodiode inside the optocoupler DC4, the anode of the photodiode is connected to the auxiliary isolation power supply SVDD through a resistor RC7, the emitter of the triode inside the optocoupler DC4 is connected to the communication reference ground MGND, and the collector is connected to the signal terminal RS_RXD and is connected to the communication power supply R+5V through a resistor RC8.

The optocouplers DC1, DC2, DC3 and DC4 are opto-isolators, and the current transmission ratio CTR is preferably more than 300%, and the forward current is 50mA. The resistors RC1, RC3, RC5 and RC7 are chip ceramic resistors, and preferably have a resistance of 820 Ω. The resistors RC2 and RC4 are chip ceramic resistors, and preferably have a resistance of 1.5kΩ. The resistors RC6 and RC8 are chip resistors, and preferably have a resistance of 1kΩ.

Working principle: the MCU and the communication chip realize communication by detecting the change of the high and low levels of the received signals.

When the MCU receives a communication signal, when a level signal RS_TXD sent by the communication chip is at a low level, voltage difference exists at two ends of a photodiode at the front end of the optocoupler DC2, the diode is conducted to emit light, a triode at the rear end is conducted to enable an S_RS_RXD signal which is originally pulled to a high level by being connected to a power supply SVDD through RC3 to be changed into a low level signal, at the moment, voltage difference exists at two ends of the photodiode at the front end of the optocoupler DC1, the diode is conducted to emit light, and the triode at the rear end is conducted to enable an M_RS_RXD signal which is originally pulled to a high level by being connected to a main system power supply DVDD through RC1 to be changed into a low level signal.

When the MCU sends a communication signal, when a level signal M_RS_TXD sent by the MCU is in a low level, voltage difference exists at two ends of a photodiode at the front end of the optocoupler DC3, the diode is conducted to emit light, a triode at the rear end is conducted to enable an S_RS_TXD signal which is originally pulled to a high level by being connected to a power supply SVDD through an RC6 to be changed into a low level signal, at the moment, voltage difference exists at two ends of a photodiode at the front end of the optocoupler DC4, the diode is conducted to emit light, and a triode at the rear end is conducted to enable an RS_RXD signal which is originally pulled to a high level by being connected to a communication power supply R+5V through an RC8 to be changed into a low level signal.

The foregoing description, in conjunction with the accompanying drawings, fully illustrates the specific embodiments herein to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in, or substituted for, those of others. The scope of the embodiments herein includes the full scope of the claims, as well as all available equivalents of the claims. The terms "first," "second," and the like herein are used merely to distinguish one element from another element and do not require or imply any actual relationship or order between the elements. Indeed the first element could also be termed a second element and vice versa. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a structure, apparatus, or device that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such structure, apparatus, or device. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a structure, apparatus or device comprising the element. Various embodiments are described herein in a progressive manner, each embodiment focusing on differences from other embodiments, and identical and similar parts between the various embodiments are sufficient to be seen with each other.

The terms "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like herein refer to an orientation or positional relationship based on that shown in the drawings, merely for ease of description herein and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus are not to be construed as limiting the utility model. In the description herein, unless otherwise specified and limited, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, mechanically or electrically coupled, may be in communication with each other within two elements, may be directly coupled, or may be indirectly coupled through an intermediary, as would be apparent to one of ordinary skill in the art. Herein, unless otherwise indicated, the term "plurality" means two or more.

The above description is only of the preferred embodiments of the present application, and is not intended to limit the present application, and various modifications and variations may be made by those skilled in the art, and it is intended to cover all modifications, variations, equivalents, and the like, which may be included in the scope of the present application, without requiring any inventive effort by those skilled in the art based on the present application.

Claims

1. The utility model provides a smart electric meter is with high withstand voltage low-speed communication isolation circuit of super high isolation which characterized in that: the circuit comprises a first-stage isolation circuit and a second-stage isolation circuit;

2. The ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart meter according to claim 1, wherein: the optocoupler DC1, the optocoupler DC2, the optocoupler DC3 and the optocoupler DC4 are optoisolators, the current transmission ratio CTR is more than 300%, and the forward current is 50mA.

3. The ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart meter according to claim 1, wherein: the resistor RC1, the resistor RC3, the resistor RC5 and the resistor RC7 are chip ceramic resistors, and the resistance is 820 omega.

4. The ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart meter according to claim 1, wherein: the resistor RC2 and the resistor RC4 are chip ceramic resistors, and the resistance value is 1.5KΩ.

5. The ultra-high isolation voltage-resistant low-speed communication isolation circuit for a smart meter according to claim 1, wherein: the resistor RC6 and the resistor RC8 are chip resistors, and the resistance value is 1k omega.