CN114465609A

CN114465609A - Normally closed solid relay

Info

Publication number: CN114465609A
Application number: CN202011246919.0A
Authority: CN
Inventors: 赵笃良; 韦跃武; 刘理想; 郭建章; 王承贵; 林永; 翟耀华; 文仁俊
Original assignee: Guizhou Zhenhua Qunying Electric Appliance Co Ltd(state-Owned No891 Factory)
Current assignee: Guizhou Zhenhua Qunying Electric Appliance Co Ltd(state-Owned No891 Factory)
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2022-05-10

Abstract

The invention discloses a normally-closed solid relay, which comprises a field effect transistor V2, a resistor R1 and an isolation circuit A1, wherein the grid electrode of the field effect transistor V2 is used as the excitation end of the field effect transistor and is connected to an output power supply through a resistor R1, the drain electrode of the field effect transistor V2 is used as the output end and is connected with a load RL, and the source electrode of the field effect transistor V2 is used as the low power supply end and is connected with the output power supply. The field effect transistor V2 in the solid relay is used as an output device, the grid of the field effect transistor is used as an excitation end of the field effect transistor and is connected with an output power supply + through a resistor R1, the drain of the field effect transistor is used as an output end and is connected with a load RL, the source of the field effect transistor is used as a low power supply end and is connected with the output power supply-, and when no input is loaded on an isolation circuit, the field effect transistor V2 is in a conducting state; when the input is loaded on the isolation circuit, the isolation circuit connects the grid of the field effect transistor V2 to the output power supply-, so that the field effect transistor V2 is in a cut-off state; the whole circuit realizes the conduction of the output end of the normally closed solid relay under the state of no bias power supply.

Description

Normally closed solid relay

Technical Field

The invention belongs to the field of electromechanical elements, and particularly relates to a normally-closed solid relay.

Background

The normally closed solid-state relay generally uses a normally closed solid-state relay composed of enhancement mode fets, and needs to provide a bias power supply and a control terminal for switching the output state. The normally closed solid relay is made of an enhanced field effect tube, so that a plurality of circuit modes are realized, but the principle is basically the same. The functional block diagram of a normally closed solid-state relay composed of an enhanced field effect transistor as an output device is shown in the attached figure 1, and the working principle is as follows:

after the bias end is electrified, if the control end is in a non-excitation state, the input circuit works to generate energy, the energy is transmitted to the driving circuit in an isolation mode through the isolation circuit, the driving circuit converts the energy into an electric signal, the electric signal is added between the grid electrode and the source electrode of the field effect tube, the field effect tube is conducted, and a power supply is provided for a load; after the control end applies the excitation signal, the input circuit stops working and does not provide energy for the isolation circuit any more, so that no electric signal is generated in the driving circuit, and the field effect tube is cut off to cut off the load power supply. The working state of the field effect transistor is changed through the state change of the control end, and then the working state of the load is changed.

The circuit has the advantages that the types of the enhanced field effect transistors are various, the output capability is far higher than that of the depletion type field effect transistor, large current output can be realized, and the output current can reach dozens of amperes.

The circuit has the disadvantage of requiring a bias power supply, and when there is no bias power supply, the output terminal is in an off state, rather than a conducting state similar to the normally closed contact of an electromagnetic relay.

Disclosure of Invention

The invention aims to solve the technical problems of the existing normally-closed solid-state relay comprising an enhancement type field effect transistor, and aims to provide a normally-closed solid-state relay which does not need a bias power supply, keeps an output end in a conducting state when no excitation input exists, and keeps the output end in a stopping state when excitation input exists.

In order to achieve the purpose of the invention, the normally-closed solid-state relay provided by the invention comprises a field-effect tube V2, a resistor R1 and an isolation circuit A1, wherein the grid electrode of the field-effect tube V2 is connected to an output power supply + through a resistor R1 as the excitation end of the field-effect tube, the drain electrode of the field-effect tube V2 is used as the output end to be connected with a load RL, and the source electrode of the field-effect tube V2 is used as a low power supply end to be connected with the output power supply-.

The normally-closed solid relay provided by the invention has the advantages that the field effect tube V2 is used as an output device, the grid of the field effect tube is used as an excitation end of the field effect tube and is connected with an output power supply + through a resistor R1, the drain of the field effect tube is used as an output end and is connected with a load RL, the source of the field effect tube is used as a low power supply end and is connected with the output power supply-, and when no input is loaded on an isolation circuit, the field effect tube V2 is in a conducting state; when the input is loaded on the isolation circuit, the isolation circuit connects the grid of the field effect transistor V2 to the output power supply-, so that the field effect transistor V2 is in a cut-off state; the whole circuit realizes the conduction of the output end of the normally closed solid relay under the state of no bias power supply.

In some embodiments, the solid-state relay further comprises a zener diode D1 connected in parallel between the gate and the source of the fet V2. The voltage between the grid electrode and the source electrode of the field effect transistor V2 is clamped at the voltage stabilizing value of the voltage stabilizing diode D1 through the voltage stabilizing diode D1, and the grid electrode and the source electrode of the field effect transistor V2 are protected from being broken down by too high voltage.

In some embodiments, the isolation circuit is an optocoupler, which may be composed of a light emitting diode D1 and a phototransistor V1 packaged together, or may be composed of a separate light emitting diode D1 and a separate phototransistor V1.

In some embodiments, the solid-state relay provided by the invention may further include a resistor R2, wherein one end of the resistor R2 is connected to the anode of the light emitting diode D1, and the other end is used for connecting to an input +.

The invention has the beneficial effects that: the solid relay provided by the invention realizes the conduction of the output end of the normally closed solid relay by using the field effect tube under the state without a bias power supply, and the field effect tube has high current output capability, so that the solid relay provided by the invention can provide high current output when the output end of the solid relay keeps the conduction state, and the high current output is realized.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

fig. 1 is a schematic block diagram of a conventional normally closed solid-state relay composed of enhancement mode fets;

FIG. 2 is one of the circuit schematic diagrams of the solid state relay provided by the present invention;

FIG. 3 is a second schematic circuit diagram of the solid state relay of the present invention;

FIG. 4 is a third schematic circuit diagram of the solid state relay of the present invention;

FIG. 5 is a fourth schematic circuit diagram of the solid state relay of the present invention;

in the drawings: the output power supply + and the output power supply-are the positive electrode and the negative electrode of an external power supply; and the input + and the input-are the positive pole and the negative pole of an external input power supply.

Detailed Description

Exemplary embodiments will now be described more fully with reference to the accompanying drawings. The exemplary embodiments, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. In the drawings, the size of some of the elements may be exaggerated or distorted for clarity. The same reference numerals denote the same or similar structures in the drawings, and thus detailed descriptions thereof will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the subject matter of the present disclosure can be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures, methods, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

The normally closed solid relay provided by the invention has the remarkable characteristics that when the input end of the normally closed solid relay has no excitation signal, the output end of the normally closed solid relay is in a conducting state, is connected with a load and can bear heavy current output; when the input end of the invention is applied with an excitation signal, the output end of the invention is in a cut-off state, and the load is turned off, which is similar to a normally closed contact of an electromagnetic relay.

The solid-state relay provided by the present invention is described in detail with reference to the following embodiments.

Example one

Referring to fig. 2 and 4, the normally-closed solid-state relay in the present embodiment includes an isolation circuit a1 for input/output isolation, a field-effect transistor V2, and a resistor R1; the isolation circuit a1 here employs an optocoupler comprising a light emitting diode D1 and a phototransistor V1.

The positive electrode and the negative electrode of an external input power supply are respectively connected with the anode and the cathode of the light-emitting diode D1, the collector of the phototriode V1 is connected with the grid of the field-effect tube V2, and the emitter is used for being connected with the source of the field-effect tube V2; the grid of the field effect transistor V2 is also connected with one end of a resistor R1, the other end of the resistor R1 is connected with an output power supply +, the drain of the field effect transistor V2 is used as an output end to be connected with a load RL, and the source is used as a low power supply end to be connected with the output power supply-.

The working principle of the fixed relay is as follows: when the input end has no excitation signal, the light emitting diode D1 in the optical coupler does not emit light, the collector and the emitter of the phototriode V1 in the optical coupler are in a cut-off state, the output power supply + provides grid source voltage for the field effect transistor V2 through the resistor R1, the drain and the source of the field effect transistor V2 are in a conduction state, current flows to the output power supply from the output power supply + through the drain and the source of the load resistors RL and V2, the conduction of the V2 provides current for the load resistor, and the load RL works normally.

When the input end applies an excitation signal, the light-emitting diode D1 emits light to irradiate the phototriode V1, the collector and the emitter of the V1 are in a conducting state, the grid-source voltage of the field-effect tube V2 is lower than the grid cut-off voltage of the field-effect tube V2, the drain and the source of the field-effect tube V2 are in a cut-off state, the current path of the load RL is blocked, and the load RL does not work.

The circuit structure of the solid-state relay in this embodiment is a current input type.

Example two

Referring to fig. 3 and 5, the normally-closed solid-state relay in the present embodiment includes an isolation circuit a1 for input/output isolation, a field-effect transistor V2, a resistor R1, and a resistor R2; the isolation circuit a1 here employs an optocoupler comprising a light emitting diode D1 and a phototransistor V1.

The positive electrode and the negative electrode of an external input power supply are respectively connected with the anode and the cathode of the light-emitting diode D1, the collector of the phototriode V1 is connected with the grid of the field-effect tube V2, and the emitter is used for being connected with the source of the field-effect tube V2; the grid of the field effect transistor V2 is also connected with one end of a resistor R1, the other end of the resistor R1 is connected with an output power supply +, the drain electrode of the field effect transistor V2 is used as an output end and is connected with a load RL, and the source electrode is used as a low power supply end and is connected with the output power supply-; the resistor R2 is connected in series between the anode of the LED D1 and the anode of the external input power supply.

The solid-state relay provided by the embodiment is changed from a current input type to a voltage input type after the resistor R2 is added, but the on-off processes of the optocoupler and the field-effect transistor V2 are not changed, and the working principle is not changed.

The solid-state relay provided in the first and second embodiments further includes a zener diode D1 connected in parallel between the gate and the source of the fet V2.

The optocoupler provided by the invention can be composed of a light emitting diode D1 and a phototransistor V1 which are packaged together, or can be composed of a separate light emitting diode D1 and a separate phototransistor V1.

The field effect transistor adopts an enhanced field effect transistor which has high current output capacity, so that the enhanced field effect transistor is adopted to realize the conduction of the output end of the normally closed solid relay, and the high current output can be realized.

The models and parameters of an optical coupler, a resistor R1, a voltage stabilizing diode D1 and a field effect tube V2 in the solid relay provided by the invention can be selected according to circuit requirements, for example, the optical coupler adopts a 4N37 photoelectric coupler, R1 is 100k omega, the voltage stabilizing value of D1 is 15V, and the V2 adopts a field effect tube IRFH 7184; when the above component models are adopted, the technical indexes of the solid relay provided by the text are as follows: the input current is 10mA, the output voltage is 28V, the output current is 10A, and the transient voltage is 100V.

The solid relay provided by the invention selects different field effect transistor indexes, the output capacity can be adjusted, the drain-source voltage of the field effect transistor influences the output voltage of the invention, and the drain-source current of the field effect transistor influences the output current of the invention. The drain-source voltage and the drain-source current of the field effect transistor are positively correlated with the output voltage and the output current of the solid relay.

The present disclosure has been described in terms of the above-described embodiments, which are merely exemplary of the implementations of the present disclosure. It must be noted that the disclosed embodiments do not limit the scope of the disclosure. Rather, variations and modifications are possible within the spirit and scope of the disclosure, and these are all within the scope of the disclosure.

Claims

1. A normally closed solid-state relay is characterized in that: the solid relay comprises a field effect transistor V2, a resistor R1 and an isolation circuit A1, wherein the grid electrode of the field effect transistor V2 is used as the excitation end of the field effect transistor and is connected to an output power supply through a resistor R1, the drain electrode of the field effect transistor V2 is used as the output end and is connected with a load RL, and the source electrode of the field effect transistor V2 is used as a low power supply end and is connected with the output power supply-.

2. The normally closed solid-state relay according to claim 1, wherein: and a voltage stabilizing diode D1 connected between the grid and the source of the field effect transistor V2 in parallel.

3. The normally closed solid-state relay according to claim 1 or 2, characterized in that: the isolation circuit is an optocoupler, and the optocoupler can be composed of a light emitting diode D1 and a phototriode V1 which are packaged together, or can be composed of an independent light emitting diode D1 and an independent phototriode V1.

4. The normally closed solid-state relay according to claim 3, wherein: a resistor R2 may be further included, wherein one end of the resistor R2 is connected to the anode of the led D1, and the other end is used for connecting to the input +.