CN103633613B - Too little current automatic power-off protection circuit and charger - Google Patents
Too little current automatic power-off protection circuit and charger Download PDFInfo
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- CN103633613B CN103633613B CN201310577376.4A CN201310577376A CN103633613B CN 103633613 B CN103633613 B CN 103633613B CN 201310577376 A CN201310577376 A CN 201310577376A CN 103633613 B CN103633613 B CN 103633613B
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Abstract
Too little current automatic power-off protection circuit and charger; this circuit includes: the first relay, the second relay, current sensing means, the first current-amplifying device and direct current supply module; first relay and the second relay are serially connected in main current supply circuit after being respectively provided with a normally opened contact and two normally opened contact parallel connections, and the first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay close. Main current supply circuit is carried out the real-time sampling of electric current by current sensing means; it is amplified driving electromagnetic coil relay to sample rate current by current-amplifying device; its contact being connected in main current supply circuit is disconnected when electric current is too small; can effectively prevent current reflux; avoid the adverse effect that load is caused by the charging of lasting too little current; but also the function of super-high-current monitoring can be increased simultaneously; realize too little current protection and the function of super-high-current protection simultaneously, be effectively protected load equipment safe operation.
Description
Technical field
The present invention relates to power protecting circuit technical field, be specifically related to a kind of too little current automatic power-off protection circuit and charger.
Background technology
On market, the safe operation of electromechanical equipment is served critically important protective effect by the device such as common short-circuit protection, super-high-current power-off protection. Such as, electric motor car, motor bicycle have been widely known products, and it is with features such as " energy-saving and environmental protection, convenience, at a low price ", it is thus achieved that huge market. Battery charger is substantially per car one, and society's recoverable amount is huge. But, existing battery charger, all without power-off (civil power of input) defencive function, does not more have " excessive, too little current bidirectional protective " function, therefore Frequent Accidents. The event even often having causing death and huge property loss occurs. Although existing charger is when charging is near completion, accumulator can be stopped charging, but its scheme adopted is: calculated in advance goes out the charging curve of battery, then control chip is utilized to stop the charging work of charger in the time period of certain setting, but circuit is actually still within connection status, and it utilizes charging curve as basis for estimation, does not reflect the real-time of charging process, there is certain defect in the detection accuracy of charged state.
It is known that owing to the reason of the reason of battery charger working environment or the reason of accumulator or charger is all likely to make institute's power consumption stream increasing, super-high-current causes accumulator, charger and electric motor car or the heating of motor bicycle circuit; Thus it is likely to result in major accident. It addition, the electric current charged along with the growth in charging interval is more and more less, if forgetting to close power supply, it is easy to fill bad accumulator and even fill quick-fried, also can waste the substantial amounts of energy. But, when too small by the electric current of load (comparing with normal value), equipment can be caused great potential safety hazard equally, also can cause very big energy waste. Owing to the internal memory electricity of accumulator every time to be charged, now input voltage are all difficult to consistent with output gear, obviously improper with the time relay.
Summary of the invention
The present invention provides a kind of too little current automatic power-off protection circuit, it is possible to solve the problems referred to above.
A kind of too little current automatic power-off protection circuit that the embodiment of the present invention provides, including: the first relay, second relay, for detecting size of current in main current supply circuit the current sensing means sampled, for the first current-amplifying device being amplified processing by the electric current that current sensing means sampling obtains and the direct current supply module being used for providing DC offset voltage to the first current-amplifying device, first relay and the second relay are serially connected in main current supply circuit after being respectively provided with a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected to the feeder ear of main current supply circuit and over the ground between end after concatenating a normally closed switch, the current value that current sensing means sampling obtains is more than when setting the first monitoring threshold values, first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay close.
Preferably, described current sensing means is the current transformer with the first primary coil and the first secondary coil, primary coil that the feeder ear of main current supply circuit sequentially passes through current transformer, the parallel branch being made up of described two normally opened contacts connect load input terminal, and the electric current that the first secondary coil of current transformer will be coupled into is through one first rectification filtering module output to the first current-amplifying device.
Preferably, described first current-amplifying device includes: a NPN audion, the first resistance and the second resistance, first rectification filtering module sequentially passes through the first resistance and the second resistance connects signal ground, second resistance provides bias voltage to the base stage of a NPN audion, the emitter stage of the oneth NPN audion connects signal ground, and the colelctor electrode of a NPN audion is connected to the feeder ear of direct current supply module through the solenoid of described second relay.
Preferably, the parallel branch that the feeder ear of main current supply circuit directly powers to the load or sequentially passes through the primary coil of current transformer through a gating switch selection, being made up of described two normally opened contacts powers to the load.
Preferably, described current sensing means also includes: the second subprime coil coupled with the first primary coil, second rectification filtering module, second current-amplifying device, there is the 3rd relay of normally-closed contact and there is the 4th relay of normally opened contact, direct current supply module provides DC offset voltage for the second current-amplifying device, the electric current that second subprime coil will be coupled into is through the second rectification filtering module output to the second current-amplifying device, second current-amplifying device drives the solenoid of the 3rd relay to make the normally-closed contact of the 3rd relay disconnect when the electric current that second subprime coil is coupled to exceedes the second monitoring threshold values of setting, the solenoid of the 4th relay and the normally-closed contact of the 3rd relay constitute a series arm and are connected to the feeder ear of main current supply circuit and over the ground between end, the normally opened contact of the 4th relay is connected in main current supply circuit.
Preferably, described second current-amplifying device includes: the 2nd NPN audion, the 3rd resistance and the 4th resistance, second rectification filtering module sequentially passes through the 3rd resistance and the 4th resistance connects signal ground, 4th resistance provides bias voltage to the base stage of the 2nd NPN audion, the emitter stage of the 2nd NPN audion connects signal ground, and the colelctor electrode of the 2nd NPN audion is connected to the feeder ear of direct current supply module through the solenoid of described 3rd relay.
Preferably, also include double-point double-throw switch, direct current supply module includes transformator and the 3rd rectification filtering module, double-point double-throw switch includes the first moved end A1, the second moved end A2, the first non-moved end B1, the second non-moved end B2, the 3rd non-moved end C1 and the 4th non-moved end C2, first moved end A1 switches between the first non-moved end C1 of non-moved end B1 and the three, second moved end A2 switches between the second non-moved end C2 of non-moved end B2 and the four, and the first relay and the 4th relay are respectively provided with another normally opened contact; first moved end A1 connects the feeder ear of main current supply circuit, second moved end A2 and the first non-moved end B1 short circuit, first non-moved end B1 connects load input terminal, second non-moved end B2 sequentially passes through the series arm that the solenoid of the first relay constitutes with normally closed switch and is connected the end over the ground of main current supply circuit, second non-moved end B2 sequentially passes through the solenoid of the 4th relay and the end over the ground of the 3rd relay normally-closed contact composition series arm main current supply circuit of connection, first moved end A1, when second moved end A2 is connected respectively the first non-moved end B1 and the second non-moved end B2, the feeder ear of main current supply circuit is respectively to the solenoid of the first relay and the 4th relay, the feeder ear that the solenoid of the first relay and the 4th relay is also connected to main current supply circuit respectively through its another normally opened contact constitutes self-locking structure, 3rd non-moved end C1 connects the input of current transformer primary coil, 4th non-moved end C2 is through the end over the ground of the primary coil main current supply circuit of connection of transformator, the secondary coil of transformator provides DC offset voltage through the 3rd rectification filtering module to the first direct current amplification device and the second direct current amplification device.
Preferably, first secondary coil and second subprime coil are respectively provided with at least one tap, one end of first secondary coil connects a wherein input of the first rectification filtering module, and another input of the first rectification filtering module selects to be switched to the other end or a wherein tap of the first secondary coil by one first selection switch; One end of second subprime coil connects a wherein input of the second rectification filtering module, and another input of the second rectification filtering module selects to be switched to the other end or a wherein tap of second subprime coil by one second selection switch.
Preferably, the first resistance and the 3rd resistance are adjustable resistance.
Preferably, main current supply circuit concatenates one for detecting the ammeter of load current size.
Based on above-mentioned too little current automatic power-off protection circuit, the embodiment of the present invention additionally provides a kind of charger, and this charger includes above-mentioned too little current automatic power-off protection circuit.
Technique scheme can be seen that, owing to the embodiment of the present invention adopts current sensing means that main current supply circuit carries out the real-time sampling of electric current, and by current-amplifying device, sample rate current is amplified with the condition of satisfied driving electromagnetic coil relay, electromagnetic coil relay is driven in time when electric current too small (less than this circuit configuration value), disconnect its contact being connected in main current supply circuit, make to be completely between main current supply circuit and load the state of disconnection, can effectively prevent current reflux, avoid the adverse effect that load is caused by the charging of lasting too little current.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the structured flowchart of too little current automatic power-off protection circuit in the embodiment of the present invention;
Fig. 2 is the circuit theory diagrams adding the too little current automatic power-off protection circuit that super-high-current automatically powers off defencive function in the embodiment of the present invention.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments. Based on the embodiment in the present invention, all other embodiments that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.
Embodiment:
The embodiment of the present invention provides a kind of charger, this charger includes a kind of too little current automatic power-off protection circuit, this too small automatic power-off protection circuit is as shown in Figure 1, including: the first relay, second relay, for detecting size of current in main current supply circuit the current sensing means sampled, for the first current-amplifying device being amplified processing by the electric current that current sensing means sampling obtains and the direct current supply module being used for providing DC offset voltage to the first current-amplifying device, first relay and the second relay are serially connected in main current supply circuit after being respectively provided with a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected to the feeder ear of main current supply circuit and over the ground between end after concatenating a normally closed switch, the current value that current sensing means sampling obtains is more than when setting the first monitoring threshold values, first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay close.
It is understandable that, since being that too little current automatically powers off protection, then need a monitoring threshold values, then think that electric current is too small less than this monitoring threshold values, the measure automatically powered off can be taked, therefore, the the first monitoring threshold values set in the present embodiment can be determined according to load characteristic or applied environment, such as a certain load is accumulator, charge circuit can be disconnected when charging current is reduced to 20mA, this 20mA may be set to the first monitoring threshold values, when the current value that current sampling device collects is more than 20mA, the electric current of abundance can be provided to drive the second relay through the first current-amplifying device, the normally opened contact making the second relay closes, maintain charge circuit and continue charging, the current value collected once current sampling device is less than 20mA, after the processing and amplifying of the first current-amplifying device, this current value still cannot meet the condition driving the second electromagnetic coil relay, then the normally opened contact of the second relay returns to original state, charge circuit disconnects. it will be appreciated by those skilled in the art that, the ratio of its sampling can be set for current sampling device, this enforcement such as, carry out current sample as current sensing means to main current supply circuit using current transformer, so, the oversampling ratio of electric current can be determined by arranging the turn ratio of primary coil and secondary coil, again it will be understood that, the magnification ratio of the first current-amplifying device can also be arranged, the setting of the first monitoring threshold values is that those skilled in the art are caned and independently set according to the circuit structure in the present embodiment, repeats no more herein.
In the embodiment of the present invention, the feeder ear of main current supply circuit accesses AC220V civil power; main current supply circuit is connected to hold the loop formed over the ground for being connected load by power supply (civil power); its load includes the various electrical equipment needing to use power supply; it is specifically the rear end power consumption module of charger in embodiments of the present invention; certainly, in other domestic electric appliances such as electric cooker, electric refrigerator, still can use the too little current automatic power-off protection circuit in the embodiment of the present invention.
In the embodiment of the present invention, the first relay is to start offer preparatory condition for the stable of the second relay, namely after the feeder ear of main current supply circuit accesses AC220V civil power, its electric current is through the solenoid of the first relay and normally closed switch, drive the normally opened contact Guan Bi of solenoid controlled first relay of the first relay, main current supply circuit can directly be powered to the load by the contact of the first relay, to ensure whole normal circuit operation. it is appreciated that if power utilization environment now is made without too little current detection, then can not turn off normal open switch. owing to the driving of solenoid of the second relay exists certain relation with the electric current in main current supply circuit, namely the electric current in main current supply circuit is carried out detection sampling by current sensing means, and be amplified processing through the first current-amplifying device, drive the solenoid of the second relay, the normally opened contact making the second relay closes, now, in main current supply circuit the normally opened contact of the first relay and the normally opened contact of the second relay all closes and and be connected in main current supply circuit, realize the pattern of " dual pathways is powered ", now, if disconnection normally closed switch, then the solenoid no current of the first relay passes through, the normally opened contact of the first relay in main current supply circuit is off, in main current supply circuit, the dual pathways is powered and is become individually being closed by the normally opened contact of the second relay connecting, and, as long as main current supply circuit has sufficiently large current intensity, then current sensing means will real-time sampling, and for driving the solenoid of the second relay, realize the normally opened contact of the second relay in main current supply circuit to be kept closed, for load supplying. once electric current is too small in main current supply circuit, the current value that then current sensing means sampling obtains is too small, also the solenoid of the second relay cannot be driven even across the processing and amplifying of the first current-amplifying device, now, the normally opened contact of the second relay in main current supply circuit returns to off-state, and main current supply circuit stops powering to the load, and it is in being fully disconnected physically, stop current reflux completely, and in the occasion charged to accumulator, battery discharging can have been prevented.
As can be seen here, Control is all carried out in real time time too small by the embodiment of the present invention for electric current in the sampling of electric current and main current supply circuit, the disconnection of main current supply circuit is controlled to be comparatively objective by it, therefore, accuracy can be better than the control mode based on the existing charging curve to generate in advance. It addition, without using control chip in whole circuit, from the viewpoint of circuit cost, there is bigger advantage, it is simple to reduce the production cost of product, be conducive to being widely popularized of market.
Specifically, as shown in Figure 2, current sensing means is the current transformer with the first primary coil L1 and the first secondary coil L2 in embodiments of the present invention, first secondary coil L2 and the first primary coil L1 coupling, the feeder ear of main current supply circuit sequentially passes through the primary coil L1 of current transformer, by described two normally opened contact ka34, the parallel branch that kb34 is constituted connects load input terminal (namely powering to the load), the electric current that first secondary coil of current transformer will be coupled into is through one first rectification filtering module output to the first current-amplifying device, resistance sampling circuit can be adopted to realize for current sensing means in other embodiments, but resistance sampling circuit has extra power consumption, the present embodiment adopt current transformer to have energy consumption as current sampling circuit low, sampling feature promptly and accurately. it is understandable that for rectification filtering module be technology known in those skilled in the art, the structure and working principle of rectification filtering module is not done herein and too much repeat, as seen from Figure 2, rectification filtering module in the present embodiment all adopts diode rectification (in figure D3, D4), then passing through energy storage filter capacitor C11 to be filtered processing, the stable signal of output smoothing is to the first current-amplifying device. and the first current-amplifying device includes in the present embodiment: a NPN audion Q1, the first resistance R2 and the second resistance R3, first rectification filtering module sequentially passes through the first resistance R2 and the second resistance R3 and connects signal ground, second resistance R3 provides bias voltage to the base stage of a NPN audion Q1, the emitter stage of the oneth NPN audion Q1 connects signal ground, and the colelctor electrode of a NPN audion Q1 is connected to the feeder ear of direct current supply module through the solenoid kb of described second relay. visible, in the present embodiment, the first current-amplifying device adopts the linear amplification modes of crystal triode, processing and amplifying process has power supplementary characteristic, it is understandable that, those skilled in the art can adopt the electric current that sampling is obtained by other current amplification circuits to be amplified in other embodiments, to drive the solenoid of the second relay, repeat no more herein. in order to realize the controllability of the first current-amplifying device further, namely can monitor threshold values by circuit to first to be set, first resistance R2 adopts adjustable resistance, such as, when the resistance of the first resistance R2 increases, then current sensing means needs sample bigger electric current and can drive the solenoid of the second relay.
In the embodiment of the present invention, the second relay also has another normally opened contact kb12; direct current supply module outfan VDD sequentially passes through another normally opened contact kb12 of the second relay, a resistance R4 and a display lamp S2 connects signal ground; therefore; whole circuit be in too little current automatically power off guard mode time; display lamp S2 can be bright, to point out user.
Defencive function is automatically powered off in order to realize super-high-current further, described in the present embodiment, current sensing means also includes: the second subprime coil L3 coupled with the first primary coil L1, second rectification filtering module, second current-amplifying device, there is the 3rd relay of normally-closed contact and there is the 4th relay of normally opened contact, direct current supply module provides DC offset voltage for the second current-amplifying device, the electric current that second subprime coil L3 will be coupled into is through the second rectification filtering module output to the second current-amplifying device, second current-amplifying device drives the solenoid kc of the 3rd relay to make the normally-closed contact kc34 of the 3rd relay disconnect when the second subprime coil L3 electric current being coupled to exceedes the second monitoring threshold values of setting, the normally-closed contact kc34 of solenoid kd and the three relay of the 4th relay constitutes a series arm and is connected to the feeder ear of main current supply circuit and over the ground between end, the normally opened contact kd34 of the 4th relay is connected in main current supply circuit.
Described second current-amplifying device includes: the 2nd NPN audion Q2, the 3rd resistance R5 and the 4th resistance R6, second rectification filtering module sequentially passes through the 3rd resistance R5 and the four resistance R6 and connects signal ground, 4th resistance R6 provides bias voltage to the base stage of the 2nd NPN audion Q2, the emitter stage of the 2nd NPN audion Q2 connects signal ground, and the colelctor electrode of the 2nd NPN audion Q2 is connected to the feeder ear VDD of direct current supply module through the solenoid kc of described 3rd relay. In the present embodiment, the second rectification filtering module and the first rectification filtering module have identical circuit structure, repeat no more herein. It is true that the second current-amplifying device and above-mentioned first current-amplifying device also have identical circuit structure, all adopt crystal triode that electric current is carried out linear amplification, ensure electromagnetic coil relay connection in the loop simultaneously. Its operation principle referring to above-mentioned first current-amplifying device, can repeat no more herein.
In order to realize the controllability of the second current-amplifying device further, namely can monitor threshold values by circuit to second to be set, 3rd resistance R5 adopts adjustable resistance, such as, when the resistance of the 3rd resistance R5 increases, then second subprime coil needs are coupled to bigger electric current and can drive the solenoid of the 3rd relay so that it is normally-closed contact disconnects.
In actual use, the setting of the second monitoring threshold values can be far longer than the first monitoring threshold values, it will be understood by those skilled in the art that, what the second monitoring threshold values was corresponding is big current protection (overcurrent protection), such as monitoring the electric current of main current supply circuit, to reach 20A be then stream, need to take protective measure, what the first monitoring threshold values was corresponding is too little current protection, therefore the higher of threshold value setting ought to be monitored by second, and first monitoring threshold values can set smaller, such as 20mA, and as mentioned above, current sample is to gather the electric current in main current supply circuit with certain proportion, therefore, the electric current that suitable reduction sampling obtains can be carried out by the oversampling ratio of current sampling device, then second subprime coil can adopt the coil that the number of turn is less to couple, to reduce it, the current value obtained, therefore, in actual mechanical process, as long as the suitable number of turn adjusting second subprime coil and the second current-amplifying device can also reduce the setting of the second monitoring threshold values, when relatively big or the second current-amplifying device the amplification of the number of turn even at second subprime coil is less, second monitoring threshold values can monitor threshold values less than first, but still the excessive or too little current monitoring in the main current supply circuit that can correspond to. certainly, second monitoring threshold values can set that and monitors threshold values more than first in other embodiments, the electric current that the sampling of current sensing means obtains can also be divided into two-way export respectively to the first current-amplifying device and the second current-amplifying device, but, the magnification ratio of the second current-amplifying device, less than the first current-amplifying device, realizes too little current monitoring and protecting and super-high-current monitoring and protecting with this.
In order to increase the practicality of this protection circuit, the feeder ear of main current supply circuit can power to the load through the parallel branch that a gating switch selection directly powers to the load or sequentially passes through the primary coil of current transformer, being made up of described two normally opened contacts in other examples. This gating switch can be single-pole double-throw switch (SPDT) or alternative electrical switch. If when this protection circuit is applied in certain socket or be applied to the power input part timesharing of certain household electrical appliance, it is possible to chosen whether the function starting too little current detection protection and super-high-current detection protection by gating switch.
In the embodiment of the present invention, the 3rd relay also has another normally-closed contact kc12; direct current supply module outfan VDD sequentially passes through another normally-closed contact kc12 of the 3rd relay, a resistance R7 and a display lamp S3 connects signal ground; therefore; whole circuit be in super-high-current automatically power off guard mode time; display lamp S3 can be bright, to point out user.
As shown in Figure 2, the embodiment of the present invention further increases double-pole double-throw switch, direct current supply module includes transformator T1 and the 3rd rectification filtering module, double-point double-throw switch includes the first moved end A1, the second moved end A2, the first non-moved end B1, the second non-moved end B2, the 3rd non-moved end C1 and the 4th non-moved end C2, first moved end A1 switches between the first non-moved end C1 of non-moved end B1 and the three, second moved end A2 switches between the second non-moved end C2 of non-moved end B2 and the four, and the first relay and the 4th relay are respectively provided with another normally opened contact ka12, kd12, first moved end A1 connects the feeder ear of main current supply circuit, second moved end A2 and the first non-moved end B1 short circuit, first non-moved end B1 connects load input terminal, second non-moved end B2 sequentially passes through the series arm that the solenoid of the first relay constitutes with normally closed switch and is connected the end over the ground of main current supply circuit, second non-moved end B2 sequentially passes through the end over the ground of solenoid kd and the three relay normally-closed contact kc34 composition series arm main current supply circuit of connection of the 4th relay, first moved end A1, when second moved end A2 is connected respectively the first non-moved end B1 and the second non-moved end B2, the feeder ear of main current supply circuit is respectively to the solenoid ka of the first relay and the 4th relay, kd powers, the solenoid ka of the first relay and the 4th relay, kd is also respectively through its another normally opened contact ka12, kd12 is connected to the feeder ear of main current supply circuit and constitutes self-locking structure, 3rd non-moved end C1 connects the input of current transformer primary coil L1, 4th non-moved end C2 is through the end over the ground of the primary coil main current supply circuit of connection of transformator T1, the secondary coil of transformator T1 provides DC offset voltage through the 3rd rectification filtering module to the first direct current amplification device and the second direct current amplification device.
As can be seen here, the embodiment of the present invention adds the self-locking structure of the first relay, the 4th relay, it is possible to ensure the stability that circuit runs. double-point double-throw switch can increase the practicality of protection circuit, and it not only starts important function in realizing relay latching circuit, and is capable of the handoff functionality directly powering to the load with being powered to the load by too little current detection protection structure. when the first moved end A1 connects the first non-moved end B1, when second moved end A2 connects the second non-moved end B2, the feeder ear of main current supply circuit directly powers to the load, and the equal adhesive of normally opened contact kd34 of normally opened contact ka34 and the four relay of the first relay, the startup detecting defencive function for follow-up too little current provides path to prepare, now, by the A1 of double-point double-throw switch, A2 is switched on C1, C2, then transformator T1 powers as direct current supply module make it into duty to the first current-amplifying device and the second current-amplifying device, current transformer starts to be linked into entrance duty in main current supply circuit, too little current monitoring and super-high-current monitoring function are activated.
In order to be easy to manipulation further and regulate oversampling ratio, in the embodiment of the present invention, the first secondary coil L2 and second subprime coil L3 is respectively provided with at least one tap, one end of first secondary coil L2 connects a wherein input of the first rectification filtering module, and another input of the first rectification filtering module selects to be switched to the other end or a wherein tap of the first secondary coil by one first selection switch K2; One end of second subprime coil L3 connects a wherein input of the second rectification filtering module, and another input of the second rectification filtering module selects switch to select K3 to be switched to the other end or a wherein tap of second subprime coil by one second. In different application scenarios, the requirement of current monitoring is different, it is possible to by selecting switch to be adjusted, easy to operate, simple and practical.
The size of load current can be understood to be easy to operator further timely, better to regulate too little current monitoring state or super-high-current monitoring state, main current supply circuit concatenates one for detecting the ammeter of load current size. In the embodiment of the present invention, this ammeter is connected to the front end being positioned at load in main current supply circuit.
Feeder ear at main current supply circuit is also serially connected with electric fuse F, the feeder ear of main current supply circuit also sequentially passes through a resistance R1, a power supply indicator S1 connection is held over the ground, when the feeder ear of main current supply circuit accesses power supply, power supply indicator lights, and prompting operator has plant-grid connection.
Below in conjunction with accompanying drawing, the operation principle of too little current automatic power-off protection circuit in the embodiment of the present invention is made introduction.
When the feeder ear of main current supply circuit accesses power supply, power supply indicator S1 lights, now double-point double-throw switch switches in A1, A2 connects B1 respectively, the state of B2, power supply directly powers to the load, ammeter display load current, electric current sequentially passes through A1, B1, A2, B2 drives the solenoid kd of solenoid ka and the four relay of the first relay, all normally opened contacts Guan Bi of the first relay and the 4th relay, path is provided for loop, current transformer the first primary coil place, main current supply circuit feeder ear is powered to the first electromagnetic coil relay ka and the four electromagnetic coil relay kd respectively by contact ka12 and contact kd12, form latching circuit, the stability of holding circuit. now circuit can directly power to the load, if desired too little current monitoring function and super-high-current monitoring function are started, then switching double-point double-throw switch is to A1, A2 connects C1 respectively, the state of C2, the electric current of the feeder ear of main current supply circuit sequentially passes through A1, C1, current transformer the first primary coil, contact kd34, the parallel branch that contact kb34 and contact ka34 is constituted arrives ammeter and powers to the load, simultaneously, electric current is through another road B1, A2, C2 arrives transformer and makes direct current supply module enter duty, start the first current-amplifying device and the second current-amplifying device, then the second relay and the 3rd relay enter into duty, owing to main current supply circuit existing normal current flowing, the electric current that then current transformer the first secondary coil is coupled to can monitor threshold values more than first, make the contact kb34 adhesive of the second relay, but the electric current that now current transformer second subprime coil is coupled to can monitor threshold values (non-over-current state) less than second, so the normally-closed contact kc34 of the 3rd relay being failure to actuate, whole circuit is still stable, now disconnect normally closed switch K1, the solenoid of the first relay quits work, the contact ka12 of the first relay, ka34 all disconnects, so that main current supply circuit is only remained up by contact kd34 and contact kb34, now, if occurring, in main current supply circuit, electric current is too small, then the second relay quits work, contact kb34 disconnects, if electric current is excessive in main current supply circuit, then the solenoid of the 3rd relay is driven, contact kc34 disconnects, cause that the 4th relay quits work, contact kd34 disconnects, below realize that electric current is too small automatically powers off protection and electric current is excessive automatically powers off defencive function respectively.
The too little current the automatic power-off protection circuit above embodiment of the present invention provided and charger are described in detail, principles of the invention and embodiment are set forth by specific case used herein, and the explanation of above example is only intended to help to understand method and the core concept thereof of the present invention; Simultaneously for one of ordinary skill in the art, according to the thought of the present invention, all will change in specific embodiments and applications, in sum, this specification content should not be construed as limitation of the present invention.
Claims (10)
1. too little current automatic power-off protection circuit, it is characterized in that, including: the first relay, second relay, for detecting size of current in main current supply circuit the current sensing means sampled, for the first current-amplifying device being amplified processing by the electric current that current sensing means sampling obtains and the direct current supply module being used for providing DC offset voltage to the first current-amplifying device, first relay and the second relay are serially connected in main current supply circuit after being respectively provided with a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected to the feeder ear of main current supply circuit and over the ground between end after concatenating a normally closed switch, the current value that current sensing means sampling obtains is more than when setting the first monitoring threshold values, first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay close.
2. too little current automatic power-off protection circuit as claimed in claim 1; it is characterized in that; described current sensing means is the current transformer with the first primary coil and the first secondary coil; primary coil that the feeder ear of main current supply circuit sequentially passes through current transformer, the parallel branch being made up of described two normally opened contacts connect load input terminal, and the electric current that the first secondary coil of current transformer will be coupled into is through one first rectification filtering module output to the first current-amplifying device.
3. too little current automatic power-off protection circuit as claimed in claim 2; it is characterized in that; described first current-amplifying device includes: a NPN audion, the first resistance and the second resistance; first rectification filtering module sequentially passes through the first resistance and the second resistance connects signal ground; second resistance provides bias voltage to the base stage of a NPN audion; the emitter stage of the oneth NPN audion connects signal ground, and the colelctor electrode of a NPN audion is connected to the feeder ear of direct current supply module through the solenoid of described second relay.
4. too little current automatic power-off protection circuit as claimed in claim 2; it is characterized in that, the parallel branch that the feeder ear of main current supply circuit directly powers to the load or sequentially passes through the primary coil of current transformer through a gating switch selection, being made up of described two normally opened contacts powers to the load.
5. too little current automatic power-off protection circuit as claimed in claim 2, it is characterized in that, described current sensing means also includes: the second subprime coil coupled with the first primary coil, second rectification filtering module, second current-amplifying device, there is the 3rd relay of normally-closed contact and there is the 4th relay of normally opened contact, direct current supply module provides DC offset voltage for the second current-amplifying device, the electric current that second subprime coil will be coupled into is through the second rectification filtering module output to the second current-amplifying device, second current-amplifying device drives the solenoid of the 3rd relay to make the normally-closed contact of the 3rd relay disconnect when the electric current that second subprime coil is coupled to exceedes the second monitoring threshold values of setting, the solenoid of the 4th relay and the normally-closed contact of the 3rd relay constitute a series arm and are connected to the feeder ear of main current supply circuit and over the ground between end, the normally opened contact of the 4th relay is connected in main current supply circuit.
6. too little current automatic power-off protection circuit as claimed in claim 5; it is characterized in that; described second current-amplifying device includes: the 2nd NPN audion, the 3rd resistance and the 4th resistance; second rectification filtering module sequentially passes through the 3rd resistance and the 4th resistance connects signal ground; 4th resistance provides bias voltage to the base stage of the 2nd NPN audion; the emitter stage of the 2nd NPN audion connects signal ground, and the colelctor electrode of the 2nd NPN audion is connected to the feeder ear of direct current supply module through the solenoid of described 3rd relay.
7. too little current automatic power-off protection circuit as claimed in claim 5, it is characterized in that, also include double-point double-throw switch, direct current supply module includes transformator and the 3rd rectification filtering module, double-point double-throw switch includes the first moved end A1, second moved end A2, first non-moved end B1, second non-moved end B2, 3rd non-moved end C1 and the 4th non-moved end C2, first moved end A1 switches between the first non-moved end C1 of non-moved end B1 and the three, second moved end A2 switches between the second non-moved end C2 of non-moved end B2 and the four, first relay and the 4th relay are respectively provided with another normally opened contact, first moved end A1 connects the feeder ear of main current supply circuit, second moved end A2 and the first non-moved end B1 short circuit, first non-moved end B1 connects load input terminal, second non-moved end B2 sequentially passes through the series arm that the solenoid of the first relay constitutes with normally closed switch and is connected the end over the ground of main current supply circuit, second non-moved end B2 sequentially passes through the solenoid of the 4th relay and the end over the ground of the 3rd relay normally-closed contact composition series arm main current supply circuit of connection, first moved end A1, when second moved end A2 is connected respectively the first non-moved end B1 and the second non-moved end B2, the feeder ear of main current supply circuit is respectively to the solenoid of the first relay and the 4th relay, the feeder ear that the solenoid of the first relay and the 4th relay is also connected to main current supply circuit respectively through its another normally opened contact constitutes self-locking structure, 3rd non-moved end C1 connects the input of current transformer primary coil, 4th non-moved end C2 is through the end over the ground of the primary coil main current supply circuit of connection of transformator, the secondary coil of transformator provides DC offset voltage through the 3rd rectification filtering module to the first direct current amplification device and the second direct current amplification device.
8. too little current automatic power-off protection circuit as claimed in claim 5, it is characterized in that, first secondary coil and second subprime coil are respectively provided with at least one tap, one end of first secondary coil connects a wherein input of the first rectification filtering module, and another input of the first rectification filtering module selects to be switched to the other end or a wherein tap of the first secondary coil by one first selection switch; One end of second subprime coil connects a wherein input of the second rectification filtering module, and another input of the second rectification filtering module selects to be switched to the other end or a wherein tap of second subprime coil by one second selection switch.
9. too little current automatic power-off protection circuit as claimed in claim 5, it is characterised in that the first resistance and the 3rd resistance are adjustable resistance.
10. a charger, it is characterised in that include the too little current automatic power-off protection circuit described in any one in the claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310577376.4A CN103633613B (en) | 2013-11-18 | 2013-11-18 | Too little current automatic power-off protection circuit and charger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310577376.4A CN103633613B (en) | 2013-11-18 | 2013-11-18 | Too little current automatic power-off protection circuit and charger |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103633613A CN103633613A (en) | 2014-03-12 |
| CN103633613B true CN103633613B (en) | 2016-06-15 |
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| CN201310577376.4A Expired - Fee Related CN103633613B (en) | 2013-11-18 | 2013-11-18 | Too little current automatic power-off protection circuit and charger |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110716421B (en) * | 2018-07-11 | 2023-11-24 | 兰州大成铁路信号股份有限公司 | Execution unit switching circuit, electronic execution system comprising same and switching method |
| CN112821347B (en) * | 2021-03-17 | 2023-05-02 | 广东电网有限责任公司 | Bandpass current protection circuit |
| CN114373660B (en) * | 2022-01-25 | 2024-02-09 | 深圳市君安电气设备有限公司 | Intelligent circuit breaker |
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| CN103633613A (en) | 2014-03-12 |
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