CN102158213A - DC solid-state relay - Google Patents

Abstract

The invention discloses a DC solid-state relay, which comprises an input circuit, an isolating circuit and an output circuit. The input circuit comprises a first resistor, a second resistor, a first switching tube and a first diode, wherein the anode of the first switching tube is connected with one end of the second resistor by the first resistor, and the other end of the second resistor is connected with the emitter of the first switching tube. The isolating circuit comprises a first optical coupler and a second optical coupler, wherein the positive input end of the first optical coupler is connected with the emitter of the first switching tube; the positive and negative output ends of the second optical coupler are connected with the collector and base of the first switching tube respectively; and the positive input end of the second optical coupler is connected with the negative output end of the first optical coupler. The output circuit comprises a third resistor, a fourth resistor, a second switching tube, a third switching tube, a second diode and a third diode, wherein the negative input end of the second optical coupler is connected with the third resistor; the positive input end of the second optical coupler is connected with the base of the second switching tube; and the collector of the second switching tube is connected with the positive output end of the first optical coupler. The relay has operating value or return value parameters which can be adjusted in a relatively wider range, and meets the requirement of high speed.

Description

A kind of dc solid-state relay

Technical field

The invention belongs to the relay field, relate to a kind of solid-state relay, relate in particular to the adjustable high-speed small-size dc solid-state relay structure of a kind of low-loss, long-life and operating value or return value parameter.

Background technology

Solid-state relay is a kind of contactless electronic beam switch, it is made up of electronic component, than electromagnetic relay, have reliable operation, to external world disturb little, can be with the logical circuit compatibility, antijamming capability is strong, switching speed is fast and series of advantages such as easy to use, therefore have very wide application, can expand to the field that traditional electromagnetic relay can't be used.But the control circuit more complicated of solid-state relay, higher to the reliability requirement of element, so the application of solid-state relay also is subjected to certain restriction.Can predict, solid-state relay will develop towards small-sized, slim direction, and modern equipment is had higher requirement to the responsiveness of solid-state relay, in addition, the critical voltage of existing solid-state relay turn-on and turn-off is approximate identical, often can not precision maneuver near critical voltage, the critical flutter phenomenon takes place easily, this just requires to have certain adjusting nargin between the conducting voltage of relay and the cut-ff voltage.

Based on above strengths and weaknesses analysis to existing solid-state relay, the inventor furthers investigate existing solid-state relay structure, and through test of many times, this case produces thus.

Summary of the invention

Technical problem to be solved by this invention is at defective in the aforementioned background art and deficiency, and a kind of dc solid-state relay is provided, and its operating value or return value parameter are adjustable, the adjustable range broad, and satisfy high-speed requirement.

The present invention is for solving above technical problem, and the technical scheme that is adopted is:

A kind of dc solid-state relay comprises input circuit, buffer circuit and output circuit;

Input circuit comprises first resistance, second resistance, first switching tube and first diode, the negative electrode of first switching tube is as the VIN+ end of relay, anode connects an end of second resistance via first resistance, this end of second resistance also connects the collector electrode of first switching tube, and the other end of second resistance connects the emitter of first switching tube;

Buffer circuit comprises first optocoupler and second optocoupler, and wherein, the positive input terminal of first optocoupler connects the emitter of first switching tube, and negative input end is as the VIN-end of relay; The negative output terminal of second optocoupler connects the base stage of first switching tube, and positive output end connects the collector electrode of first switching tube, and its positive input terminal connects the negative output terminal of first optocoupler;

Output circuit comprises the 3rd resistance, the 4th resistance, the second switch pipe, the 3rd switching tube, second diode and the 3rd diode, wherein, one end of the 3rd resistance connects the negative input end of second optocoupler, the base stage of second switch pipe connects the positive input terminal of second optocoupler, collector electrode then connects the positive output end of first optocoupler, the collector electrode of described second switch pipe also connects the collector electrode of the 3rd switching tube, and as the VOUT+ of relay end, the emitter of second switch pipe then connects an end of the 4th resistance, the other end of the 4th resistance is connected with the other end of the 3rd resistance, and the VOUT-as relay holds jointly; The base stage of the 3rd switching tube is connected between the emitter and the 4th resistance of second switch pipe, and emitter connects the negative electrode of second diode, and the anode of second diode is connected with the other end of the 4th resistance; The negative electrode of the 3rd diode connects the collector electrode of second and third triode jointly, and the anode of the 3rd diode then connects the anode of second diode.

Above-mentioned first and second diode is a voltage stabilizing didoe.

After adopting such scheme, the present invention utilizes optocoupler to make up buffer circuit, and use the two-way optocoupler to form the loop of a positive feedback, in circuit moment of conducting just, the input current value rapid growth, then when returning, embody relay characteristics, thereby the conducting voltage of relay is separated with shutoff voltage, and parameter has bigger adjustable extent.

In addition,, do not relate to energy-storage travelling wave tubes such as capacitor and inductor,, satisfy small-power automation module relay requirement at a high speed so the speed that turns on and off of relay is very fast owing in the circuit design of the present invention, utilize optocoupler to realize relay characteristics.

Description of drawings

Fig. 1 is circuit theory diagrams of the present invention;

Fig. 2 is a relay characteristics schematic diagram of the present invention.

Embodiment

Below with reference to accompanying drawing, circuit connection structure of the present invention and operation principle are elaborated.

As shown in Figure 1, the invention provides a kind of dc solid-state relay, comprise input circuit, buffer circuit and output circuit; Wherein, input circuit comprises first resistance R 1, second resistance R 2, first switch transistor T 1 and the first diode D1, the negative electrode of first switch transistor T 1 is as the VIN+ end of relay, anode connects an end of first resistance R 1, and the other end of first resistance R 1 connects an end of second resistance R 2, the other end of this first resistance R 1 also connects the collector electrode of first switch transistor T 1, and the other end of second resistance R 2 then connects the emitter of first switch transistor T 1.

Buffer circuit comprises the first optocoupler U1 and the second optocoupler U2, and wherein, the positive input terminal of the first optocoupler U1 connects the emitter of first switch transistor T 1, and negative input end is as the VIN-end of relay; The negative output terminal of the second optocoupler U2 connects the base stage of first switch transistor T 1, and positive output end connects the collector electrode of first switch transistor T 1, and its positive input terminal connects the negative output terminal of the first optocoupler U1.

Output circuit comprises the 3rd resistance R 3, the 4th resistance R 4, second switch pipe T2, the 3rd switch transistor T 3, the second diode D2 and the 3rd diode D3, wherein, one end of the 3rd resistance R 3 connects the negative input end of the second optocoupler U2, the other end is as the VOUT-end of relay, the base stage of second switch pipe T2 connects the positive input terminal (also being the negative output terminal of the first optocoupler U1) of the second optocoupler U2, collector electrode then connects the positive output end of the first optocoupler U1, described collector electrode also connects the collector electrode of the 3rd switch transistor T 3, and as the VOUT+ of relay end, the emitter of second switch pipe T2 then connects an end of the 4th resistance R 4, the other end of the 4th resistance R 4 is connected with the other end of the 3rd resistance R 3, and the VOUT-as relay holds jointly; The base stage of the 3rd switch transistor T 3 is connected between the emitter and the 4th resistance R 4 of second switch pipe T2, and emitter connects the negative electrode of the second diode D2, and the anode of the second diode D2 is connected with the other end of the 4th resistance R 4, and the VOUT-as relay holds jointly; The negative electrode of the 3rd diode D3 connects the collector electrode of second and third triode T2, T3 jointly, and the anode of the 3rd diode D3 then connects the anode of the second diode D2, as the VOUT-end of relay.

In addition, in the present embodiment, the first optocoupler U1 adopts TLP127, and first and second diode D1, D2 are voltage stabilizing didoe.

Fig. 2 has illustrated input and output voltage characteristic of the present invention, comes the course of work of shutoff of the present invention and conducting is described below in conjunction with Fig. 1 and Fig. 2.

The process of its work is as follows:

For simplifying the analysis, now the various variablees in the circuit are defined: the input current of establishing input is I ₁ , the voltage stabilizing value of the first diode D1 is U ₁ , the voltage during the complete conducting of triode between the collector and emitter is U _Ce , the pressure drop of input is during the complete conducting of optocoupler U _g , the conducting voltage of circuit is U _Logical , the shutoff voltage of circuit is U _Disconnected Other parameters all as shown in Figure 2.

(1) circuit conducting phase not:

When the input voltage that applies U _{Go into} ＜ U ₁ The time, input circuit is in the state that opens circuit, and does not have electric current to pass through in the input circuit.When U _{Go into} U ₁ The time because circuit does not also have conducting, so the second optocoupler U2 also do not start working, so first switch transistor T 1 be equivalent to open circuit, then:

(1)

Wherein Being the pressure drop of optocoupler input when not having complete conducting, becoming positively related relation with input current, is a variable, but its value can not surpass 1V.

(2) the circuit turn-on stage:

In circuit stage of conducting not, when U _{Go into} U ₁ The time, though it is the first optocoupler U1 has faint conducting, also not enough so that the input voltage of the second optocoupler U2 arrives its needed conduction value.Continuation rising along with input voltage, the conducting degree of optocoupler also increases gradually, when arriving its needed conduction threshold, a positive feedback meeting is set up rapidly: the first optocoupler U1 conducting, impel the second optocoupler U2 conducting, the conducting of the second optocoupler U2 can cause the short circuit of first switch transistor T 1 again, then

(2)

Current value I ₁ Can increase rapidly, the conducting degree of the second optocoupler U2 also can increase then, forms a positive feedback like this, until the complete conducting of the first optocoupler U1.

If the electric current that needs during the complete conducting of optocoupler is I _f , the definition current value I _g Can cause the critical input current of positive feedback during for the circuit operate as normal.

(3) circuit returns the stage

When returning behind the circuit turn-on, because the effect of positive feedback finishes, thus the saturation value of input current during much larger than complete conducting, when input voltage is reduced to gradually U _Logical The time, this moment input current I ₁ I _f So circuit still continues complete conducting; When I ₁ = I _f The time, when electric current continued to reduce, reciprocal positive feedback meeting this moment was set up rapidly, and working mechanism is opposite with above-mentioned mechanism, so circuit can turn-off rapidly.

Comprehensively can get:

(3)

(4)

Wherein I _f , I _g Value can obtain a result by side circuit test, U _g Pressure drop during for the complete conducting of optocoupler, it fluctuates in a very little scope, U _Ce Voltage during for the triode conducting between the collector and emitter is definite value.

As seen, suitable adjustment R ₁ With R ₂ Value with regard to scalable turn-on and turn-off voltage, improve the characterisitic parameter of relay, the conducting voltage of relay is separated with shutoff voltage, and leaves certain nargin, can prevent that the phenomenon of critical flutter from taking place.

Above embodiment only for explanation technological thought of the present invention, can not limit protection scope of the present invention with this, every technological thought that proposes according to the present invention, and any change of being done on the technical scheme basis all falls within the protection range of the present invention.

Claims (2)

1. a dc solid-state relay comprises input circuit, buffer circuit and output circuit; It is characterized in that:

Input circuit comprises first resistance, second resistance, first switching tube and first diode, the negative electrode of first switching tube is as the VIN+ end of relay, anode connects an end of second resistance via first resistance, this end of second resistance also connects the collector electrode of first switching tube, and the other end of second resistance connects the emitter of first switching tube;

Buffer circuit comprises first optocoupler and second optocoupler, and wherein, the positive input terminal of first optocoupler connects the emitter of first switching tube, and negative input end is as the VIN-end of relay; The negative output terminal of second optocoupler connects the base stage of first switching tube, and positive output end connects the collector electrode of first switching tube, and its positive input terminal connects the negative output terminal of first optocoupler;

Output circuit comprises the 3rd resistance, the 4th resistance, the second switch pipe, the 3rd switching tube, second diode and the 3rd diode, wherein, one end of the 3rd resistance connects the negative input end of second optocoupler, the base stage of second switch pipe connects the positive input terminal of second optocoupler, collector electrode then connects the positive output end of first optocoupler, the collector electrode of described second switch pipe also connects the collector electrode of the 3rd switching tube, and as the VOUT+ of relay end, the emitter of second switch pipe then connects an end of the 4th resistance, the other end of the 4th resistance is connected with the other end of the 3rd resistance, and the VOUT-as relay holds jointly; The base stage of the 3rd switching tube is connected between the emitter and the 4th resistance of second switch pipe, and emitter connects the negative electrode of second diode, and the anode of second diode is connected with the other end of the 4th resistance; The negative electrode of the 3rd diode connects the collector electrode of second and third triode jointly, and the anode of the 3rd diode then connects the anode of second diode.

2. a kind of dc solid-state relay as claimed in claim 1 is characterized in that: described first and second diode is a voltage stabilizing didoe.