CN201001032Y - AC voltage-limiting and current-limiting safety explosion-proof DC voltage stabilizing power source device - Google Patents

Abstract

The utility model relates to an alternating current voltage limit and current limit type intrinsic safe explosion proof direct current voltage stabilized power device which is applied to the inflammable and explosive type high-danger industry such as coal mine, oil gas well, gas station and natural gas station, and relates to an alternating current voltage limit and current limit type intrinsic safe explosion proof direct current voltage stabilized power device which is used for the apparatuses and the meters which have the special requirements for a power. The utility model comprises a transformer, an alternating current bidirectional current limit circuit, an alternating current bidirectional voltage limit circuit, a rectification/filter/current limit/voltage stabilization/overvoltage protection/short circuit protection circuit. The utility model can inhibit the input end of an alternating current power from producing strong current for a power on/off instant, and also can resolve the strong current of the low voltage output end caused by short circuit and the abnormal excessive heating problem of the component because of short circuit, at the same time, the utility model has a multiple protection way intrinsic safe type power.

Description

Exchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus

Technical field

The utility model relates to a kind of being suitable for the intrinsic safe explosion-proof DC voltage-stablized source apparatus of the high risk industries of inflammable and explosive types such as colliery, oil gas well, gas station, natural gas station and other has the instrument of special requirement, the intrinsic safe explosion-proof DC voltage-stablized source apparatus that instrument is used to power supply, is meant a kind of intrinsic safe explosion-proof type DC voltage-stablized source apparatus with alternating-current bidirectional pressure limiting, alternating-current bidirectional current limiting function especially.

Background technology

The employed instruments of inflammable and explosive occasion such as colliery, oil gas well, gas station, natural gas station must meet essential safety standard (hereinafter to be referred as intrinsic safety), and giving the power supply of these instrument power supplies must be intrinsic safety electric source.But 127V or 220V alternating current that the input of intrinsic safety electric source provides from fields of employment such as colliery or gas stations, they itself are not intrinsic safety.Common intrinsic safety electric source adopts transformer that 127V or 220V alternating current are become low pressure in addition rectification, filtering, voltage stabilizing, current limliting, overvoltage protection etc. again, forms intrinsic safety output (as shown in Figure 1).In this link, the input of common transformer and output also do not meet the intrinsic safety requirement, because primary is a big inductance in fact, when it contacts bad or disconnects suddenly with power line, can produce a high voltage, at this moment can produce big electric current and big spark, and when energising just or element when producing fault, primary can produce electric current greatly.If fault does not in time obtain handling, may produce quick-fried or other phenomenon of the failure of electric mistake and actuation gas causes very serious consequence.Therefore, how to limit 127V or 220V ac power input end at the big electric current that moment of on/off electricity produces, make the low-voltage output when short circuit, be minimum short circuit current and solve components and parts because of short circuit abnormal heating problem be make it more to meet that intrinsic safety requires, the key issue of specific (special) requirements under the realistic environment for use.

Through showing to the analysis of causes of Gas Explosion Accidents in Coal Mines with to the performance test that has intrinsic safety electric source now, exist tangible security breaches at the intrinsic safety electric source that uses at present, might cause catastrophic consequence.

The utility model content

The purpose of this utility model is to provide a kind of intrinsic safe explosion-proof type DC voltage-stablized source apparatus that can suppress the big electric current that 127V or 220V ac power input end produce in on/off electricity moment; and solve big electric current that the low-voltage output causes because of short circuit and components and parts because of the unusual excessive heating problem of short circuit, have the interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus of multiple protective mode simultaneously.

For achieving the above object, technical solution of the present utility model is:

The utility model provides a kind of interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus; comprise a transformer, an alternating-current bidirectional current limiting circuit, one rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit; described rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit input connects the secondary of transformer, and the output of described interchange current-limiting circuit connects primary.

The utility model comprises that also one can absorb the issuable high-tension alternating-current bidirectional pressure limiting circuit of primary, and this alternating-current bidirectional pressure limiting circuit is connected in parallel on primary.

Further, described interchange current-limiting circuit is made of an alternating-current bidirectional current limiting circuit.

Further, described alternating-current bidirectional current limiting circuit can split into two unidirectional current-limiting circuits.

Further, described unidirectional current-limiting circuit can substitute rectifier diode, can form a full bridge rectifier with current-limiting function by four unidirectional current-limiting circuits.

Described rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit is made up of rectifier bridge B1, electrochemical capacitor E1, capacitor C 1, C2, C3, C4, resistance R 5, R6, R7, R8, triode Q4, Q5, Q6, Q7, voltage stabilizing didoe Z3, Z4, Z5, Z6, Z7; The input of rectifier bridge B1 also connects the secondary of transformer T1, the output of rectifier bridge B1 just/negative pole and connect the both positive and negative polarity of E1, C1 and E1 also connect, the utmost point of the positive pole serial connection R5 of E1, the emitter of the common port serial connection Q5 of E1 and R5, the utmost point of another utmost point serial connection R6 of R5, R5, the emitter of the common port serial connection Q4 of R6, the base stage of another utmost point serial connection Q5 of R6, R6, the utmost point of the common port serial connection R8 of Q5, the negative pole of another utmost point serial connection Z7 of R8, the base stage of the collector series connection Q4 of Q5, Q5, the emitter of the common port serial connection Q6 of Q4, the collector electrode of the collector series connection Q7 of Q4, Q4, the utmost point of the common port serial connection C2 of Q7, another utmost point of C2 connects the negative pole of E1, the utmost point of the base stage serial connection R7 of Q6, another utmost point of R7 connects the negative pole of E1, the base stage of the collector series connection Q7 of Q6, Q6, the negative pole of the common port serial connection Z3 of Q7 connects, the positive pole of Z3 connects the negative pole of E1, C3 and Z3 also connect, the positive pole of the emitter serial connection Z7 of Q7, Q7, the negative pole of the common port serial connection Z4 of Z7, the positive pole of Z4 connects the negative pole of E1, C4, Z5, Z6 also meets Z4; The negative pole of Z4 is the positive pole of output, the just very negative pole of output of Z4.

Described alternating-current bidirectional current limiting circuit is made up of diode D1, D1`, voltage stabilizing didoe Z1, Z1`, triode Q1, Q2, Q3, Q1`, Q2`, Q3`, resistance R 1, R2, R3, R4, R1`, R2`, R3`, R4`; The utmost point of the positive pole serial connection R1 of D1`, the common port of D1` and R1 is connected with the emitter of Q1, the utmost point of another utmost point serial connection R2 of R1, the base stage of another utmost point serial connection Q1 of R2, the utmost point of the common port serial connection R3 of R2 and Q1, the positive pole of another utmost point serial connection Z1 of R3, R1, the emitter of the common port serial connection Q3 of R2, the emitter of the base stage serial connection Q2 of Q3, the base stage of Q2 connects the collector electrode of Q1, Q1, the utmost point of the common port serial connection R4 of Q2, another utmost point of R4 and negative pole and the Q3 of Z1, the collector electrode of Q2 is attempted by the negative pole of D1, the utmost point of the positive pole serial connection R1` of D1, the common port of D1 and R1` is connected with the emitter of Q1`, the utmost point of another utmost point serial connection R2` of R1`, the base stage of another utmost point serial connection Q1` of R2`, the utmost point of the common port serial connection R3` of R2` and Q1`, the positive pole of another utmost point serial connection Z1` of R3`, R1`, the emitter of the common port serial connection Q3` of R`2, the emitter of the base stage serial connection Q2` of Q3`, the base stage of Q2` connects the collector electrode of Q1`, Q1`, the utmost point of the common port serial connection R4` of Q2`, another utmost point of R4` and negative pole and the Q3` of Z1`, the collector electrode of Q2` is attempted by on the negative pole of D1`.

Described alternating-current bidirectional pressure limiting circuit is made up of transient voltage inhibition diode Z7, Z8, Z7`, Z8`, resistance R 9, R9`, capacitor C 5, C5`; C5 also meets R9, the positive pole of the utmost point serial connection Z7 of R9, the negative pole of the negative pole serial connection Z8 of Z7; C5` also meets R9`, the positive pole of the utmost point serial connection Z7` of R9`, the negative pole of the negative pole serial connection Z8` of Z7`; Another utmost point of the two poles of the earth cross-over connection R9 of primary and the positive pole of Z8, the positive pole of another utmost point of R9` and Z8` also connects another utmost point of R9 and the positive pole of Z8.

Owing to adopt such scheme, the alternating-current bidirectional pressure limiting circuit that the utility model is provided with can absorb the issuable high voltage of primary, the interchange current-limiting circuit has guaranteed that ac input end can not produce big electric current, form intrinsic safety output through protective circuit.Because of transformer has been AC constant-current source, its output also is not afraid of short circuit, and output short circuit protection circuit can make output current reduce when the short circuit of intrinsic safety electric source output simultaneously, thereby makes components and parts not because of the unusual excessive heating of short circuit.The overvoltage protection voltage-stabiliser tube of three parallel connections plays triple overvoltage protections, breaks down even pipe is adjusted in voltage stabilizing, can guarantee that also output voltage is within the excursion of permission.Therefore; the utility model be have suppress 127V or 220V ac power input end when on/off electricity moment and circuit have just powered on because the big electric current that rectifying and wave-filtering electric capacity is charged and produces; and solve big electric current that the low-voltage output causes because of short circuit and components and parts because of the unusual excessive heating problem of short circuit (because can not produce big electric current), the intrinsically safe power supply that has the multiple protective mode simultaneously so can excessive heating.The utility model adopts discrete component, has that transient response is good, multiple protective, perfect performance, reliability is high and practical characteristics.

Below in conjunction with the drawings and specific embodiments the utility model is further described.

Description of drawings

The intrinsic safety electric source structure chart that Fig. 1 is common;

First example structure block diagram of Fig. 2 the utility model;

Fig. 3 alternating-current bidirectional pressure limiting circuit of the present utility model and transformer principle figure;

Fig. 4 alternating-current bidirectional current limiting circuit theory diagrams of the present utility model;

Fig. 5 rectification/filtering of the present utility model/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit schematic diagram;

Fig. 6 alternating-current bidirectional current limiting circuit application of the present utility model is in the structured flowchart of HF switch intrinsic safety electric source;

Fig. 7 alternating-current bidirectional current limiting circuit of the present utility model splits into the schematic diagram of unidirectional current-limiting circuit;

Fig. 8 is the schematic diagram of the full bridge rectifier of four unidirectional current-limiting circuits compositions of the present utility model;

Fig. 9 is that circuit theory of the present utility model is always schemed.

Embodiment

One, embodiment

Fig. 2 is first example structure figure of the present utility model.The utility model is a kind of interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus, and it is made up of two alternating-current bidirectional current limiting circuit A, an alternating-current bidirectional pressure limiting circuit and a transformer B, one rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C.The output of described two alternating-current bidirectional current limiting circuit A connects the two ends of primary respectively; the alternating-current bidirectional pressure limiting circuit is connected in parallel on the elementary of transformer, the secondary input that is connected described rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C of transformer.

The electric current of primary input is exported to alternating-current bidirectional pressure limiting circuit and transformer B after alternating-current bidirectional current limiting circuit A current limliting; absorb the issuable high voltage of primary through the alternating-current bidirectional pressure limiting circuit; by the secondary of transformer the voltage after the step-down is flowed to rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C, behind rectification, filtering, current limliting, voltage stabilizing, overvoltage protection, short-circuit protection, form intrinsic safety electric source output.

As shown in Figure 3, described alternating-current bidirectional pressure limiting circuit B mainly is made up of transient voltage inhibition diode Z7, Z8, Z7`, Z8`, resistance R 9, R9`, capacitor C 5, C5`; C5 also meets R9, the positive pole of the utmost point serial connection Z7 of R9, the negative pole of the negative pole serial connection Z8 of Z7; C5` also meets R9`, the positive pole of the utmost point serial connection Z7` of R9`, the negative pole of the negative pole serial connection Z8` of Z7`; Another utmost point of the two poles of the earth cross-over connection R9 of primary and the positive pole of Z8, the positive pole of another utmost point of R9` and Z8` also connects another utmost point of R9 and the positive pole of Z8.

As shown in Figure 4, alternating-current bidirectional current limiting circuit A mainly is made up of diode D1, D1`, voltage stabilizing didoe Z1, Z1`, triode Q1, Q2, Q3, Q1`, Q2`, Q3`, resistance R 1, R2, R3, R4, R1`, R2`, R3`, R4`; The utmost point of the positive pole serial connection R1 of D1`, the common port of D1` and R1 is connected with the emitter of Q1, the utmost point of another utmost point serial connection R2 of R1, the base stage of another utmost point serial connection Q1 of R2, the utmost point of the common port serial connection R3 of R2 and Q1, the positive pole of another utmost point serial connection Z1 of R3, R1, the emitter of the common port serial connection Q3 of R2, the emitter of the base stage serial connection Q2 of Q3, the base stage of Q2 connects the collector electrode of Q1, Q1, the utmost point of the common port serial connection R4 of Q2, another utmost point of R4 and negative pole and the Q3 of Z1, the collector electrode of Q2 is attempted by the negative pole of D1, the utmost point of the positive pole serial connection R1` of D1, the common port of D1 and R1` is connected with the emitter of Q1`, the utmost point of another utmost point serial connection R2` of R1`, the base stage of another utmost point serial connection Q1` of R2`, the utmost point of the common port serial connection R3` of R2` and Q1`, the positive pole of another utmost point serial connection Z1` of R3`, R1`, the emitter of the common port serial connection Q3` of R`2, the emitter of the base stage serial connection Q2` of Q3`, the base stage of Q2` connects the collector electrode of Q1`, Q1`, the utmost point of the common port serial connection R4` of Q2`, another utmost point of R4` and negative pole and the Q3` of Z1`, the collector electrode of Q2` is attempted by on the negative pole of D1`.

The common port of the common port of D1`, R1 and Q1 and D1, R1` and Q1` is the input and the output of any utmost point of alternating current, and because of this circuit adopts the holohedral symmetry design, optional any end is output for the input other end, and needn't distinguish polarity.

The two poles of the earth of alternating current power to the utility model by being connected in series two identical alternating-current bidirectional current limiting circuit respectively, to meet the duplicate protection requirement of intrinsic safety.

As shown in Figure 5, rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C is made up of rectifier bridge B1, electrochemical capacitor E1, capacitor C 1, C2, C3, C4, resistance R 5, R6, R7, R8, triode Q4, Q5, Q6, Q7, voltage stabilizing didoe Z3, Z4, Z5, Z6, Z7; The input of rectifier bridge B1 also connects the secondary of transformer T1, the output of rectifier bridge B1 just/negative pole and connect the both positive and negative polarity of E1, C1 and E1 also connect, the utmost point of the positive pole serial connection R5 of E1, the emitter of the common port serial connection Q5 of E1 and R5, the utmost point of another utmost point serial connection R6 of R5, R5, the emitter of the common port serial connection Q4 of R6, the base stage of another utmost point serial connection Q5 of R6, R6, the utmost point of the common port serial connection R8 of Q5, the negative pole of another utmost point serial connection Z7 of R8, the base stage of the collector series connection Q4 of Q5, Q5, the emitter of the common port serial connection Q6 of Q4, the collector electrode of the collector series connection Q7 of Q4, Q4, the utmost point of the common port serial connection C2 of Q7, another utmost point of C2 connects the negative pole of E1, the utmost point of the base stage serial connection R7 of Q6, another utmost point of R7 connects the negative pole of E1, the base stage of the collector series connection Q7 of Q6, Q6, the negative pole of the common port serial connection Z3 of Q7 connects, the positive pole of Z3 connects the negative pole of E1, C3 and Z3 also connect, the positive pole of the emitter serial connection Z7 of Q7, Q7, the negative pole of the common port serial connection Z4 of Z7, the positive pole of Z4 connects the negative pole of E1, C4, Z5, Z6 also meets Z4; The negative pole of Z4 is the positive pole of output, the just very negative pole of output of Z4.

Described transformer, alternating-current bidirectional pressure limiting circuit B and rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C can adopt the high frequency switch power that meets the intrinsic safety requirement to substitute.That is: respectively be connected in series an alternating-current bidirectional current limiting circuit A at the two poles of the earth of the input of high frequency switch power.

Fig. 6 is second embodiment of the present utility model.It is made up of alternating-current bidirectional current limiting circuit A and HF switch intrinsic safety electric source D.The output of alternating-current bidirectional current limiting circuit A connects HF switch intrinsic safety electric source D.The electric current of input HF switch intrinsic safety electric source D is to export to HF switch intrinsic safety electric source D to form intrinsic safety output again after alternating-current bidirectional current limiting circuit A current limliting.

Fig. 7 is the schematic diagram that the utility model alternating-current bidirectional current limiting circuit A splits into unidirectional current-limiting circuit.

Fig. 8 substitutes four full bridge rectifier schematic diagrams that rectifier diode constitutes by four unidirectional current-limiting circuits.In first embodiment of the present utility model, rectifying part can substitute with four unidirectional current-limiting circuits shown in Figure 8 among rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C.But since main in first embodiment of the present utility model be in order to limit the big electric current that 127V or 220V ac power input end produced in moment of on/off electricity, so be the input that two unidirectional current-limiting circuit reverse parallel connections is placed AC power, and owing to carried out current limliting at ac power input end, so just no longer repeated current limliting in rectifying part.But, then can substitute full bridge rectifier commonly used with Fig. 8 if be applied in the high-precision electronic instrument.The big electric current that causes when the charging of rectifying and wave-filtering electric capacity or other elements are produced faults when this full bridge rectifier can better be eliminated circuit and just powered on.

Fig. 9 is that the circuit theory of first embodiment of the present utility model is always schemed.

Two, operation principle:

1, the principle of alternating-current bidirectional pressure limiting circuit B

Alternating current is from the elementary input of transformer, and transformer is a big inductance in fact, when it contacts bad or disconnects suddenly with AC power, can produce high voltage.Alternating-current bidirectional pressure limiting circuit B of the present utility model is connected in parallel on transformer primary to absorb transient voltage.Operation principle is that Z7, Z8 get the 200V voltage-stabiliser tube, negative pole links to each other, it is two-way that all (this conducting voltage is applicable to the AC power of 127V ± 10% that mine adopts in the 200V conducting, its crest voltage is 127V * 110% * 1.414 ≈ 200V), when transformer produced a high voltage, because of the voltage at electric capacity two ends can not suddenly change, this voltage was added on Z7, the Z8 by R9 and C5, Z7, Z8 can absorb the transient voltage that exceeds 200V, have guaranteed that transformer primary can not produce high voltage.And play the step-down effect simultaneously by transformer T1.

Z7, Z8 select for use the P6KE200A transient voltage to suppress diode (use two series connection to compare and use a bi-directional voltage to suppress diode, can bear more high-power) when the input voltage unusual fluctuations, and C5 selects 104PF/400V for use, and R9 selects 2K2/3W for use.

According to the essential safety requirement, must use dual pressure limiting with the assurance reliability, thus also go up R9`, C5`, Z7`, Z8` again, to make the usefulness of duplicate protection.

According to the intrinsic safety requirement, R9, C5, Z7, Z8, R9`, C5`, Z7`, Z8` must and the input of transformer be potted in together.

2, the principle of alternating-current bidirectional current limiting circuit 1

As shown in Figure 4, when the alternating voltage of input be a right positive left side when bearing, Fig. 4 first half conducting Lower Half is ended, and the electric current of the first half flows through D1, enters the constant-current source circuit that is formed by R1, R2, Q1, Q2, Q3, R4, and the peak current that is limited is $\mathrm{Iop}\left(A\right)=\frac{\mathrm{Vbe}1}{R1\left(\mathrm{\Ω}\right)}=\frac{0.60\left(V\right)}{R1\left(\mathrm{\Ω}\right)}$ (less because of the operating current of Q1, as, to get Vbe1=0.60V) so its Vbe is also less, its average current $\stackrel{\‾}{\mathrm{Iop}}\left(A\right)=0.707\mathrm{Iop},$ Promptly $\stackrel{\‾}{\mathrm{Iop}}\left(A\right)=\frac{0.707\×0.60\left(V\right)}{R1\left(\mathrm{\Ω}\right)}\≈\frac{0.42\left(V\right)}{R1\left(\mathrm{\Ω}\right)}$ (formula one), example: when

When getting 50mA, $R1\left(\mathrm{\Ω}\right)=\frac{0.42\left(V\right)}{0.05\left(A\right)}=8.4\left(\mathrm{\Ω}\right),$ 8.4 Ω can use 8.2 Ω/0.25W high-precision metal film resistance.When Q1 and R4 determined, the precision of this constant-current source only depended on the precision of R1.The R3 of Fig. 4, the effect of Z1 are: when the voltage at A, A` two ends increased, because R4 exists, IR4 increases made the IC1 of Q1 increase, IB1 increases, Vbe1 also increases, and the electric current of this constant-current source will slightly increase thereupon.At this moment add R3, Z1, R2 is gone up produce some pressure drops, impel VR1 constant substantially, so that the electric current of constant-current source keeps substantially constant.The value computational methods of R3, Z1 are as follows: example when A, A` both end voltage when 3V is raised to 100V, it is about 10% that electric current increases, and at this moment just makes VR1 decline 10%, i.e. 0.60V * 10%, R1 gets 470 Ω resistance, at this moment Z1 gets the 2.7V voltage-stabiliser tube, then $R3\left(\mathrm{\Ω}\right)\≈\frac{100-(2.7+0.60)\left(V\right)}{0.60\left(V\right)\×10\%}\×R1\left(\mathrm{\Ω}\right)\≈757.5\left(\mathrm{K\Ω}\right)$ (formula two), desirable 750K Ω resistance during actual design, inserts the 0-100V stabilized voltage power supply to the A of Fig. 4, A` two ends and confirms by actual measurement.When input voltage during at 3V-100V, input current is constant substantially.

This interchange current-limiting circuit is actually by two unidirectional current-limiting circuit reverse parallel connections to be formed, and when input voltage is left side when positive right negative, Fig. 4 Lower Half conducting first half ends, and analytical method is the same.

The key element of Fig. 4 is Q2, Q2`, Q3, Q3`.When input ac voltage was 127V or 220V, Q3, Q3` can select MJE13003 (400V/1.5A/14W) or MJE13005 (400V/4A/60w) for use, and its Hfe generally at 30-40 doubly.Q2, Q2` can select the transistor of 2N3440 Vceo=400V-450V such as (450V/1A/1W) for use, and its Hfe generally at 60-80 doubly.When input ac voltage was 127V, Q2, Q2` also can select the transistor of 2SC227 (300V/0.1A/0.75W) or 2SC2610 Vceo=300V such as (300V/0.1A/0.80W) for use, and this type of transistor model is more.

The pressure drop when operate as normal of this alternating-current bidirectional constant-current source is about 3

, actual efficiency higher (efficient of in fact common intrinsic safety electric source is all on the low side, and the utility model efficient belongs to than higher).

According to the essential safety requirement, must adopt dual current limliting to guarantee reliability, historical facts or anecdotes border circuit need adopt the two poles of the earth of Fig. 4 circuit difference incoming transport input power supply of two.

According to the intrinsic safety requirement, Fig. 4 circuit must be potted in the box or adopt the thick film encapsulation, and the common port of the common port of D1`, R1 and Q1 and D1, R1` and Q1` is the input and the output of any utmost point of alternating current.Have only the lead-in wire at these two ends to expose after the embedding, because of this circuit adopts the holohedral symmetry design, optional any end is output for the input other end, and needn't distinguish polarity.

Alternating-current bidirectional current limiting circuit of the present utility model is actually by two unidirectional current-limiting circuit reverse parallel connections to be formed, so it also can split into two unidirectional current-limiting circuit (see figure 7)s.Can form a full bridge rectifier (see figure 8) by four so unidirectional current-limiting circuits, the big electric current that causes when the charging of rectifying and wave-filtering electric capacity or other elements are produced faults when this full bridge rectifier can be eliminated circuit and just powered on current-limiting function.

3, the principle of rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit C is as follows

As shown in Figure 5, rectifier bridge B1 plays rectification and buffer action, and the electric charge of the last storage of C1, E1 can not discharged by the AC port, and R5, R6, Q4, Q5 play metering function, and the electric current account form that is limited is $\mathrm{Io}\left(A\right)=\frac{\mathrm{Vbe}4}{R5\left(\mathrm{\Ω}\right)}=\frac{0.65\left(V\right)}{R5\left(\mathrm{\Ω}\right)}$ (formula three); when Io gets 500mA; R5=1.3 Ω; R7; Q6; Z3; Q7 plays pressure stabilization function; R7 wherein; Q6 is easy constant-current source, C2; C3 is a filter capacitor, and value must meet the intrinsic safety requirement; output voltage is Vo (V)=VZ3-0.65 (V); when being output as 12V, voltage-stabiliser tube Z3 gets 12.7V, and the precision of voltage regulation can reach the precision of common three terminal regulator Vo ± 5%; C4 is voltage stabilizing output filtering; less by intrinsic safety requirement value, the overvoltage protection voltage-stabiliser tube of three parallel connections is got 12.7V/5W, under triple current-limiting protections in front; break down even pipe is adjusted in voltage stabilizing, also can protect output voltage within the excursion of permission.Because of transformer has been AC constant-current source, its output also is not afraid of short circuit, forms output short circuit protection circuit but designed simultaneously by R8, Z7, R6, Q5; when the output short circuit, under the effect of Z7, R8, the electric current of Q5 increases; the electric current of Q4 is reduced, thereby output current is reduced.As long as make pressure drop on the VR6 near 0.65V, output current is reduced to about about 10mA, after short circuit was got rid of, under the effect of simple and easy constant-current source R7, Q6, Vo rose, and VR6 reduces gradually until disappearance, and output voltage reverts to normal voltage automatically.

And according to the requirement of intrinsic safety electric source, rectification, filtering, current limliting, voltage stabilizing, overvoltage protection part should be potted in the box, and what expose has only input the two poles of the earth and output the two poles of the earth, has four ports.

The key element of Fig. 5 is Q4, Q7 and Z4, Z5, Z6.Q4 can select MJE2955T (60V/10A/75W) or TIP42C (100V/6A/65W) etc. for use, Q7 can select MJE3055T (60V/10A/75W) or TIP41C (100V/6A/65W) etc. for use, in addition, the power of any voltage-stabiliser tube among Z4, Z5, the Z6 all will be selected the real output near intrinsic safety electric source, is higher than more than the power output twice of intrinsic safety electric source to guarantee the power that three voltage-stabiliser tubes can bear when in parallel.

Must consider when the highest alternating voltage peak (AC127V * 110% * 1.414) because of ac input end and meet voltage, the current requirements of intrinsic safety.When operate as normal, then must when the minimum effective value of alternating voltage, (AC127V * 90%) enough power output can be arranged, and when the output of step-down and intrinsic safety, adopted the transformer step-down and the linear voltage stabilization technology of poor efficiency commonly used, guaranteeing again has the certain power allowance, so power output of the present utility model is more less than common intrinsic safety electric source.But if adopt the alternating-current bidirectional current limiting circuit of two Fig. 4, add efficient than the higher high frequency switch power (as shown in Figure 6) that intrinsic safety requires that meets, power output then of the present utility model can be improved largely.

If step-down and intrinsic safety input must be adopted transformer step-down and linear voltage stabilization technology, and keep the power output of common intrinsic safety electric source again, interchange input current then of the present utility model requires bigger than intrinsic safety, but under the effect of alternating-current bidirectional pressure limiting technology and alternating-current bidirectional current limiting technology, electric spark that ac input end produced and thermal effect also will be far smaller than electric spark and the thermal effect that common intrinsic safety electric source produces.

If input voltage, input current are by intrinsic safety requirement value, then the input of transformer of the present utility model and output are under the malfunction of operate as normal or regulation, and the electric spark of generation and thermal effect can not lighted explosive mixture on every side.But because of the AC power of 127V or 220V is the power supply of non-intrinsic safety, so press the intrinsic safety regulation

Casing of the present utility model still need adopt explosion-proof design.

Through test, the utility model is to alternating-current bidirectional pressure limiting technology and alternating-current bidirectional current limiting technology that the intrinsic safety electric source input stage adopts, can effectively suppress 127V or 220V ac power input end when on/off electricity moment and circuit have just powered on because big electric current that charging produces to rectifying and wave-filtering electric capacity and ac power input end contact the big electric current of generation when bad.Even the input stage contact is bad; or output stage produces fault (as: internal short-circuit or break down); alternating-current bidirectional pressure limiting technology of the present utility model can absorb the issuable high voltage of primary; and the alternating-current bidirectional current limiting technology can guarantee that ac input end can not produce big electric current; solving big electric current that the intrinsic safety electric source output causes because of short circuit and components and parts simultaneously because of the unusual excessive heating problem of short circuit, is a kind of intrinsically safe power supply that has the multiple protective mode simultaneously.

Three, actual parameter is set

Below the setting of actual parameter when illustrating that with two examples the utility model is applied in dissimilar intrinsic safety electric equipments.

Example 1, input voltage, input current are by the DC12V intrinsic safety electric source of the intrinsic safety requirement value of I class colliery electrical installation.

As shown in Figure 9, the component parameters of beating " * " is calculated as follows:

1, the calculating of alternating-current bidirectional pressure limiting element:

The colliery is AC:127V ± 10% with AC power, its peak-peak voltage is 127V * 110% * 1.414=200V, then Z7, Z8, Z7`, Z8` get transient voltage inhibition diode P6KE200A (200V/5W, transient peak power 600W/1ms), C5, C5` get 104J/400V electric capacity, and R9, R9` get 2K2/3W resistance.

2, the calculating of alternating-current bidirectional constant-current source:

According to GB3836.4-2000 explosive gas atmosphere electrical installation essential safe type standard.The voltage/current of I class colliery electrical installation, electric current is 35mA when voltage is 200V, the peak current when this is crest voltage, its current effective value are 35 ÷ 1.414=25mA, with this as input current of the present utility model, then by formula one ( $\stackrel{\‾}{\mathrm{Iop}}\left(A\right)=\frac{0.707\×0.60\left(V\right)}{R1\left(\mathrm{\Ω}\right)}\≈\frac{0.42\left(V\right)}{R1\left(\mathrm{\Ω}\right)}$ ) calculate, R1=16.8 Ω (getting 10 Ω+6.8 Ω high-precision metal film resistances series connection), by formula two ( $R3\left(\mathrm{\Ω}\right)\≈\frac{100-(2.7+0.60)\left(V\right)}{0.60\left(V\right)\×10\%}\×R1\left(\mathrm{\Ω}\right)\≈757.5\left(\mathrm{K\Ω}\right)$ ) calculate, R3=757.5K Ω determines that with stabilized voltage power supply actual measurement back R3 is 750K Ω.

The design's minimum average B configuration input power is 127V * 90% * 25mA ≈ 2.85W.

The calculating of 3, rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection intrinsic safety electric source output stage:

The efficient of general linear stabilized power supply can only reach about 50%, add the loss of alternating-current bidirectional constant-current source, transformer, rectifying and wave-filtering etc., the design's actual efficiency is greatly about about 40%, promptly when output voltage is DC12V, can export the 100mA electric current; getting intrinsic safety output current limiting value is 100mA, by formula three ( $\mathrm{Io}\left(A\right)=\frac{\mathrm{Vbe}4}{R5\left(\mathrm{\Ω}\right)}=\frac{0.65\left(V\right)}{R5\left(\mathrm{\Ω}\right)}$ ) calculate, R5=6.5 Ω (with the high-precision metal film resistance parallel connection of two 13 Ω), the choosing method of all the other elements indicates with reference to Fig. 7.

4, about the points for attention of triode:

Triode Q3, Q3` (MJE13003), Q4 (MJE2955T), Q7 (MJE3055T) be finned suitably.

The design is applicable to input voltage DC12V, the maximum current intrinsic safety electric equipment less than 100mA.

Example 2, output voltage, output current are by the DC12V intrinsic safety electric source of IIC class electric equipment requirement value.

According to GB3836.4-2000 explosive gas atmosphere electrical installation IIC class electric equipment essential safe type standard.The design output voltage is that DC12V, output current are 500mA, and leaves certain electric current allowance, and the output current limiting design is about 525mA.Reach example 1 described computational methods as shown in Figure 9, play " * " element and be calculated as follows:

R5=1.24 Ω, R1=3.3 Ω, R3 confirm as 820K Ω with actual measurement as calculated, and because of power output is bigger, Z4, Z5, Z6 can select 12.7V/5W (as: P6KE13A) for use, and Q3, Q3` can select MJE13005 for use, and all fin suitably strengthen.

The design is applicable to input voltage DC12V, maximum current less than/equal the intrinsic safety electric equipment of 500mA.

In sum, the utility model is owing to adopted alternating-current bidirectional pressure limiting and alternating-current bidirectional current limiting technology at power input, the electric spark and the thermal effect that make the utility model be produced under the malfunction of regulation greatly reduce, and can be when output short-circuit short circuit current be reduced to extremely low state, make components and parts can effectively not reduce installation personnel because of not installing, safeguarding the serious consequence that may cause under the powering-off state in violation of rules and regulations because of the short circuit abnormal heating.Therefore, the utility model is particularly suitable for using in the high risk industries of inflammable and explosive types such as the outstanding colliery industry of the high gas of China and oil, natural gas and other has the instrument of special requirement, the intrinsically safe power supply device that instrument is used to power supply.

Claims (7)

1, exchanges pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus; it comprises a transformer, one rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit; rectification/filtering/current limliting/voltage stabilizing/overvoltage protection/short-circuit protection circuit input connects the secondary of transformer; it is characterized in that: it comprises that one exchanges current-limiting circuit, and the output of described interchange current-limiting circuit connects primary.

2, interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus according to claim 1, it is characterized in that it comprises that also one can absorb the issuable high-tension alternating-current bidirectional pressure limiting circuit of primary, this alternating-current bidirectional pressure limiting circuit is connected in parallel on primary.

3, interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus according to claim 1 is characterized in that described interchange current-limiting circuit is made of an alternating-current bidirectional current limiting circuit.

4, interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus according to claim 1 is characterized in that described interchange current-limiting circuit is actually by two that can split into two unidirectional current-limiting circuits unidirectional current-limiting circuit reverse parallel connections to form.

5, interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus according to claim 1, it is characterized in that described interchange current-limiting circuit can split into two unidirectional current-limiting circuits, can form a full bridge rectifier with current-limiting function by four unidirectional current-limiting circuits.

6, interchange pressure-limit current-limit type intrinsic safe explosion-proof DC voltage-stablized source apparatus according to claim 1 is characterized in that: be made up of diode D1, D1`, voltage stabilizing didoe Z1, Z1`, triode Q1, Q2, Q3, Q1`, Q2`, Q3`, resistance R 1, R2, R3, R4, R1`, R2`, R3`, R4` at described alternating-current bidirectional current limiting circuit; The utmost point of the positive pole serial connection R1 of D1`, the common port of D1` and R1 is connected with the emitter of Q1, the utmost point of another utmost point serial connection R2 of R1, the base stage of another utmost point serial connection Q1 of R2, the utmost point of the common port serial connection R3 of R2 and Q1, the positive pole of another utmost point serial connection Z1 of R3, R1, the emitter of the common port serial connection Q3 of R2, the emitter of the base stage serial connection Q2 of Q3, the base stage of Q2 connects the collector electrode of Q1, Q1, the utmost point of the common port serial connection R4 of Q2, another utmost point of R4 and negative pole and the Q3 of Z1, the collector electrode of Q2 is attempted by the negative pole of D1, the utmost point of the positive pole serial connection R1` of D1, the common port of D1 and R1` is connected with the emitter of Q1`, the utmost point of another utmost point serial connection R2` of R1`, the base stage of another utmost point serial connection Q1` of R2`, the utmost point of the common port serial connection R3` of R2` and Q1`, the positive pole of another utmost point serial connection Z1` of R3`, R1`, the emitter of the common port serial connection Q3` of R`2, the emitter of the base stage serial connection Q2` of Q3`, the base stage of Q2` connects the collector electrode of Q1`, Q1`, the utmost point of the common port serial connection R4` of Q2`, another utmost point of R4` and negative pole and the Q3` of Z1`, the collector electrode of Q2` is attempted by on the negative pole of D1`.

7, intrinsic safe explosion-proof type DC voltage-stablized source apparatus according to claim 1 is characterized in that: be made up of transient voltage inhibition diode Z7, Z8, Z7`, Z8`, resistance R 9, R9`, capacitor C 5, C5` at described alternating-current bidirectional pressure limiting circuit; C5 also meets R9, the positive pole of the utmost point serial connection Z7 of R9, the negative pole of the negative pole serial connection Z8 of Z7; C5` also meets R9`, the positive pole of the utmost point serial connection Z7` of R9`, the negative pole of the negative pole serial connection Z8` of Z7`; Another utmost point of the two poles of the earth cross-over connection R9 of primary and the positive pole of Z8, the positive pole of another utmost point of R9` and Z8` also connects another utmost point of R9 and the positive pole of Z8.

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