CN103633613A - Over small-current automatic power-off protection circuit and charger - Google Patents
Over small-current automatic power-off protection circuit and charger Download PDFInfo
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- CN103633613A CN103633613A CN201310577376.4A CN201310577376A CN103633613A CN 103633613 A CN103633613 A CN 103633613A CN 201310577376 A CN201310577376 A CN 201310577376A CN 103633613 A CN103633613 A CN 103633613A
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Abstract
The invention discloses an over small-current automatic power-off protection circuit and a charger. The circuit comprises a first relay, a second relay, a current detection device, a first current amplifying device and a direct current power supplying module; the first relay and the second relay are respectively provided with a normally opening contact; the two normally opening contacts are connected in parallel and are then serially connected into a main power supplying loop; the first current amplifying device drives an electromagnetic coil of the second relay to close the normally opening contact of the second relay; the current detection device performs real time current sampling on the main power supplying loop; the sampled current is amplified by the current amplifying device to drive an electromagnetic coil of the relay; the contact connected into the main power supplying loop is disconnected when the current is over small, so the current backflow can be effectively prevented, the functions of over small current protection and overlarge current protection are realized, and the safe operation of load equipment can be effectively protected.
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 device such as common short-circuit protection, super-high-current power-off protection has played very important protective effect to the safe operation of electromechanical equipment.For example, electric motor car, motor bicycle have been widely known products, and it,, with features such as " energy-saving and environmental protection, convenience, at a low price ", has obtained huge market.Battery charger is one of per car substantially, and social recoverable amount is huge.Yet existing battery charger does not all have power-off (civil power of input) defencive function, more there is no " excessive, too little current bidirectional protective " function, so Frequent Accidents.Even often there is the event of causing death and huge property loss to occur.Although existing charger is when charging is near completion, can stop charging to storage battery, but its scheme adopting is: calculated in advance goes out the charging curve of battery, then utilize control chip in the time period of certain setting, to stop the charging work of charger, but circuit is in fact still in connection status, and it utilizes charging curve as basis for estimation, do not reflect the real-time of charging process, in the detection accuracy of charged state, there is certain defect.
As everyone knows, because the reason of the reason of battery charger operational environment or the reason of storage battery or charger all may make institute's power consumption stream increasing, super-high-current causes storage battery, charger and electric motor car or the heating of motor bicycle circuit; So just may cause a serious accident.In addition, the electric current charging along with the growth in charging interval is more and more less, if forget powered-down, is easy to fill bad storage battery and even fills quick-friedly, also can waste a large amount of energy.Yet, when the electric current by load too small (with normal value comparison), can cause great potential safety hazard to equipment equally, also can cause very large energy waste.Due to the internal memory electric weight of each storage battery to be charged, now input voltage and output gear be all difficult to consistent, obviously improper with the time relay.
Summary of the invention
The invention provides a kind of too little current automatic power-off protection circuit, can address the above problem.
A kind of too little current automatic power-off protection circuit that the embodiment of the present invention provides, comprise: the first relay, the second relay, current sensing means for detection of size of current in main current supply circuit sampling, for the electric current that current sensing means sampling is obtained, amplifies the first current-amplifying device of processing and for the direct current supply module of DC offset voltage is provided to the first current-amplifying device, the first relay and the second relay are serially connected in main current supply circuit after having respectively a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected in series and is connected to the feeder ear of main current supply circuit after a normally closed switch and over the ground between end, the current value that current sensing means sampling obtains is greater than while setting the first monitoring threshold values, the first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay closed.
Preferably, described current sensing means is the current transformer with the first primary coil and the first secondary coil, the feeder ear of main current supply circuit connects load input terminal through the primary coil of current transformer, the parallel branch consisting of described two normally opened contacts successively, and the first secondary coil of current transformer exports through one first rectification filtering module the electric current being coupled to first current-amplifying device.
Preferably, described the first current-amplifying device comprises: a NPN triode, the first resistance and the second resistance, the first rectification filtering module connects signal ground through the first resistance and the second resistance successively, the second resistance provides bias voltage to the base stage of a NPN triode, the emitter of the one NPN triode connects signal ground, and the collector electrode of a NPN triode is connected to the feeder ear of direct current supply module through the solenoid of described the second relay.
Preferably, the feeder ear of main current supply circuit is selected directly to power to the load or through the primary coil of current transformer, the parallel branch consisting of described two normally opened contacts, power to the load successively through a gating switch.
Preferably, described current sensing means also comprises: with the second subprime coil of the first primary coil coupling, the second rectification filtering module, the 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, second subprime coil exports through the second rectification filtering module the electric current being coupled to second current-amplifying device, the second current-amplifying device second subprime coil coupling to electric current surpass to set the second monitoring threshold values time drive the solenoid of the 3rd relay that the normally-closed contact of the 3rd relay is disconnected, the normally-closed contact of the solenoid of the 4th relay and the 3rd relay form a series arm be connected to the feeder ear of main current supply circuit and over the ground end between, the normally opened contact of the 4th relay is connected in main current supply circuit.
Preferably, described the second current-amplifying device comprises: the 2nd NPN triode, the 3rd resistance and the 4th resistance, the second rectification filtering module connects signal ground through the 3rd resistance and the 4th resistance successively, the 4th resistance provides bias voltage to the base stage of the 2nd NPN triode, the emitter of the 2nd NPN triode connects signal ground, and the collector electrode of the 2nd NPN triode is connected to the feeder ear of direct current supply module through the solenoid of described the 3rd relay.
Preferably, also comprise double-point double-throw switch, direct current supply module comprises transformer and the 3rd rectification filtering module, double-point double-throw switch comprises 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, the first moved end A1 switches between the first non-moved end B1 and the 3rd non-moved end C1, the second moved end A2 switches between the second non-moved end B2 and the 4th non-moved end C2, and the first relay and the 4th relay have respectively another normally opened contact; the first moved end A1 connects the feeder ear of main current supply circuit, the second moved end A2 and the first non-moved end B1 short circuit, the first non-moved end B1 connects load input terminal, the second non-moved end B2 is connected the end over the ground of main current supply circuit through the solenoid of the first relay successively with the series arm of normally closed switch formation, the second non-moved end B2 forms with the 3rd relay normally-closed contact the end over the ground that series arm is connected main current supply circuit through the solenoid of the 4th relay successively, the first moved end A1, when the 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 powered to the solenoid of the first relay and the 4th relay respectively, the solenoid of the first relay and the 4th relay is also connected to respectively the feeder ear formation self-locking structure of main current supply circuit by its another normally opened contact, the 3rd non-moved end C1 connects the input of current transformer primary coil, the 4th non-moved end C2 connects the end over the ground of main current supply circuit through the primary coil of transformer, the secondary coil of transformer 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, the first secondary coil and second subprime coil have respectively at least one tap, one end of the 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 of the first secondary coil or a wherein tap by one first selector 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 of second subprime coil or a wherein tap by one second selector switch.
Preferably, the first resistance and the 3rd resistance are adjustable resistance.
Preferably, in main current supply circuit, be connected in series an ammeter for detection of load current size.
Based on above-mentioned too little current automatic power-off protection circuit, the embodiment of the present invention also provides a kind of charger, and this charger has comprised above-mentioned too little current automatic power-off protection circuit.
Technique scheme can be found out, because adopting current sensing means, the embodiment of the present invention main current supply circuit is carried out to the real-time sampling of electric current, and by current-amplifying device, sample rate current is amplified to meet the condition that drives electromagnetic coil relay, when electric current too small (being less than this circuit set point), drive in time electromagnetic coil relay, disconnect it and be connected to the contact in main current supply circuit, make the complete state in disconnecting between main current supply circuit and load, can effectively prevent current reflux, the adverse effect of having avoided lasting too little current charging to cause load.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
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 that added the too little current automatic power-off protection circuit of super-high-current auto-breaking defencive function in the embodiment of the present invention.
Embodiment
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, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making all other embodiment that obtain under creative work prerequisite, belong to the scope of protection of the invention.
Embodiment:
The embodiment of the present invention provides a kind of charger, this charger has comprised a kind of too little current automatic power-off protection circuit, this too small automatic power-off protection circuit as shown in Figure 1, comprise: the first relay, the second relay, current sensing means for detection of size of current in main current supply circuit sampling, for the electric current that current sensing means sampling is obtained, amplifies the first current-amplifying device of processing and for the direct current supply module of DC offset voltage is provided to the first current-amplifying device, the first relay and the second relay are serially connected in main current supply circuit after having respectively a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected in series and is connected to the feeder ear of main current supply circuit after a normally closed switch and over the ground between end, the current value that current sensing means sampling obtains is greater than while setting the first monitoring threshold values, the first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay closed.
Be understandable that, since be the protection of too little current auto-breaking, need a monitoring threshold values, be less than this monitoring threshold values and think that electric current is too small, can take the measure of auto-breaking, therefore, the first monitoring threshold values of setting in the present embodiment is to determine according to load characteristic or applied environment, for example a certain load is storage battery, when being reduced to 20mA, charging current can disconnect charge circuit, this 20mA can be set as the first monitoring threshold values, when the current value that current sampling device collects is greater than 20mA, through the first current-amplifying device, can provide sufficient electric current to drive the second relay, make the normally opened contact of the second relay closed, maintain charge circuit and continue charging, the current value collecting once current sampling device is less than 20mA, after the amplification of the first current-amplifying device is processed, this current value still cannot meet the condition that drives the second electromagnetic coil relay, the normally opened contact of the second relay returns to initial condition, 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, the current transformer of for example usining in this enforcement carries out current sample as current sensing means to main current supply circuit, so, can decide by the turn ratio of primary coil and secondary coil is set the sampling ratio of electric current, be appreciated that equally, the magnification ratio of the first current-amplifying device also can arrange, the setting of the first monitoring threshold values is that those skilled in the art institute can, according to the autonomous setting of the circuit structure in the present embodiment, repeat no more herein.
The feeder ear of main current supply circuit access AC220V civil power in the embodiment of the present invention; main current supply circuit is for being connected to and being held over the ground formed loop by power supply (civil power) connection load; its load has comprised the various power consumption equipments that need to use power supply; concrete is the rear end power consumption module of charger in embodiments of the present invention; certainly, in the domestic electric appliances such as other electric cookers, 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 that stable startup for the second relay provides preparatory condition, after the feeder ear access AC220V of main current supply circuit civil power, its electric current is through solenoid and the normally closed switch of the first relay, drive the normally opened contact closure of solenoid controlled first relay of the first relay, main current supply circuit can directly power to the load by the contact of the first relay, to guarantee whole circuit normal operation.Be appreciated that if power utilization environment now does not need to carry out too little current detection, can not disconnect normal open switch.Owing to there is certain relation in the driving of the solenoid of the second relay and the electric current in main current supply circuit, be that current sensing means detects sampling to the electric current in main current supply circuit, and amplify processing through the first current-amplifying device, drive the solenoid of the second relay, make the normally opened contact of the second relay closed, now, in main current supply circuit the normally opened contact of the normally opened contact of the first relay and the second relay all closed and and be connected in main current supply circuit, realize the pattern of " binary channels power supply ", now, if disconnection normally closed switch, the solenoid no current of the first relay passes through, the normally opened contact of the first relay in main current supply circuit is in off-state, in main current supply circuit, binary channels power supply becomes the closed connection of the independent normally opened contact by the second relay, and, as long as there is enough large current strength in main current supply circuit, current sensing means just can real-time sampling, and for driving the solenoid of the second relay, the normally opened contact of realizing the second relay in main current supply circuit is kept closed, for load supplying.Once electric current is too small in main current supply circuit, the current value that current sensing means sampling obtains is too small, even process and also cannot drive the solenoid of the second relay through the amplification 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 in disconnection completely physically, stop current reflux completely, and in the occasion to charge in batteries, can prevent battery discharging.
As can be seen here, in the embodiment of the present invention, Control is all carried out in real time when in the sampling of electric current and main current supply circuit, electric current is too small, it is comparatively objective that its disconnection to main current supply circuit is controlled, therefore, in accuracy, can be better than that existing to take the charging curve generating be in advance basic control mode.In addition, in whole circuit, without using control chip, from circuit cost aspect, there is larger advantage, be convenient to reduce product production cost, be conducive to the extensive popularization in market.
Particularly, 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, the first secondary coil L2 and the first primary coil L1 coupling, the feeder ear of main current supply circuit passes through the primary coil L1 of current transformer successively, by described two normally opened contact ka34, the parallel branch that kb34 forms connects load input terminal (powering to the load), the first secondary coil of current transformer exports through one first rectification filtering module the electric current being coupled to first current-amplifying device, for current sensing means, can adopt resistance sampling circuit to realize in other embodiments, but resistance sampling circuit has extra power consumption, in the present embodiment, adopt current transformer to there is energy consumption as current sampling circuit low, sampling feature promptly and accurately.Be understandable that for rectification filtering module be technology known in those skilled in the art, the structure of rectification filtering module and operation principle are not done too much and repeated herein, as seen from Figure 2, rectification filtering module in the present embodiment all adopts diode rectification (D3, D4 in figure), then by energy storage filter capacitor C11, carry out filtering processing, signal to the first current-amplifying device that output smoothing is stable.And the first current-amplifying device comprises in the present embodiment: a NPN triode Q1, the first resistance R 2 and the second resistance R 3, the first rectification filtering module connects signal ground through the first resistance R 2 and the second resistance R 3 successively, the second resistance R 3 provides bias voltage to the base stage of a NPN triode Q1, the emitter of the one NPN triode Q1 connects signal ground, and the collector electrode of a NPN triode Q1 is connected to the feeder ear of direct current supply module through the solenoid kb of described the second relay.Visible, in the present embodiment, the first current-amplifying device adopts the linear amplification mode of transistor, amplify in processing procedure and there is power supplementary characteristic, be understandable that, the electric current that those skilled in the art can adopt other current amplification circuits to obtain sampling in other embodiments amplifies, to drive the solenoid of the second relay, repeat no more herein.In order further to realize the controllability of the first current-amplifying device, can to the first monitoring threshold values, set by circuit, the first resistance R 2 adopts adjustable resistance, for example, when the resistance of the first resistance R 2 increases, current sensing means need to sample the solenoid that larger electric current can drive the second relay.
In the embodiment of the present invention, the second relay also has another normally opened contact kb12; direct current supply module output VDD is connected signal ground through another normally opened contact kb12, a resistance R 4 and an indicator light S2 of the second relay successively; therefore; at whole circuit during in too little current auto-breaking guard mode; indicator light S2 can be bright, to point out user.
In order further to realize super-high-current auto-breaking defencive function, described in the present embodiment, current sensing means also comprises: with the second subprime coil L3 of the first primary coil L1 coupling, the second rectification filtering module, the 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, second subprime coil L3 exports through the second rectification filtering module the electric current being coupled to second current-amplifying device, the electric current that the second current-amplifying device is coupled at second subprime coil L3 drives the solenoid kc of the 3rd relay that the normally-closed contact kc34 of the 3rd relay is disconnected while surpassing the second monitoring threshold values of setting, the normally-closed contact kc34 of the solenoid kd of the 4th relay and the 3rd relay form a series arm be connected to the feeder ear of main current supply circuit and over the ground end between, the normally opened contact kd34 of the 4th relay is connected in main current supply circuit.
Described the second current-amplifying device comprises: the 2nd NPN triode Q2, the 3rd resistance R 5 and the 4th resistance R 6, the second rectification filtering module connects signal ground through the 3rd resistance R 5 and the 4th resistance R 6 successively, the 4th resistance R 6 provides bias voltage to the base stage of the 2nd NPN triode Q2, the emitter of the 2nd NPN triode Q2 connects signal ground, and the collector electrode of the 2nd NPN triode Q2 is connected to the feeder ear VDD of direct current supply module through the solenoid kc of described the 3rd relay.In the present embodiment, the second rectification filtering module has identical circuit structure with the first rectification filtering module, repeats no more herein.In fact, the second current-amplifying device also has identical circuit structure with above-mentioned the first current-amplifying device, all adopts transistor to carry out linearity to electric current and amplifies, and guarantees the connection of electromagnetic coil relay in loop simultaneously.Its operation principle can, referring to above-mentioned the first current-amplifying device, repeat no more herein.
In order further to realize the controllability of the second current-amplifying device, can to the second monitoring threshold values, set by circuit, the 3rd resistance R 5 adopts adjustable resistance, for example, when the resistance of the 3rd resistance R 5 increases, second subprime coil need to be coupled to the solenoid that larger electric current can drive the 3rd relay, and its normally-closed contact is disconnected.
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 large current protection (overcurrent protection), it is overcurrent that the electric current of for example monitoring main current supply circuit reaches 20A, need to take safeguard measure, what the first monitoring threshold values was corresponding is too little current protection, therefore ought to be by the second monitoring threshold value setting higher, and first monitoring threshold values can set smaller, 20mA for example, and as mentioned above, current sample is to gather the electric current in main current supply circuit with certain proportion, therefore, can carry out the suitable electric current that sampling obtains that reduces by the sampling ratio of current sampling device, second subprime coil can adopt the coil that the number of turn is less to reduce the current value that its coupling obtains, therefore, in actual mechanical process, as long as the number of turn and second current-amplifying device of suitable adjustment second subprime coil also can reduce the setting of the second monitoring threshold values, even in the situation that the number of turn of second subprime coil multiplication factor large or the second current-amplifying device is less, the second monitoring threshold values can be less than the first monitoring threshold values, but still the monitoring of the excessive or too little current in the main current supply circuit that can correspond to.Certainly; the second monitoring threshold values can be set and be greater than the first monitoring threshold values in other embodiments; the electric current that also sampling of current sensing means can be obtained is divided into two-way and exports respectively the first current-amplifying device and the second current-amplifying device to; but; the magnification ratio of the second current-amplifying device is less than the first current-amplifying device, with this, realizes too little current monitoring and protecting and super-high-current monitoring and protecting.
In order to increase the practicality of this protective circuit, in other embodiment, the feeder ear of main current supply circuit can be selected directly to power to the load or through the primary coil of current transformer, the parallel branch consisting of described two normally opened contacts, power to the load successively through a gating switch.This gating switch can be single-pole double-throw switch (SPDT) or alternative electronic switch.If when this protective circuit is applied in certain socket or be applied to the power input part timesharing of certain household electrical appliance, can select whether to start by gating switch that too little current detects protection and super-high-current detects the function of protecting.
In the embodiment of the present invention, the 3rd relay also has another normally-closed contact kc12; direct current supply module output VDD is connected signal ground through another normally-closed contact kc12, a resistance R 7 and an indicator light S3 of the 3rd relay successively; therefore; at whole circuit during in super-high-current auto-breaking guard mode; indicator light S3 can be bright, to point out user.
As shown in Figure 2, the embodiment of the present invention has further increased by a double-point double-throw switch, direct current supply module comprises transformer T1 and the 3rd rectification filtering module, double-point double-throw switch comprises 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, the first moved end A1 switches between the first non-moved end B1 and the 3rd non-moved end C1, the second moved end A2 switches between the second non-moved end B2 and the 4th non-moved end C2, and the first relay and the 4th relay have respectively another normally opened contact ka12, kd12, the first moved end A1 connects the feeder ear of main current supply circuit, the second moved end A2 and the first non-moved end B1 short circuit, the first non-moved end B1 connects load input terminal, the second non-moved end B2 is connected the end over the ground of main current supply circuit through the solenoid of the first relay successively with the series arm of normally closed switch formation, the second non-moved end B2 forms with the 3rd relay normally-closed contact kc34 the end over the ground that series arm is connected main current supply circuit through the solenoid kd of the 4th relay successively, the first moved end A1, when the 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 power supply, the solenoid ka of the first relay and the 4th relay, kd is also respectively by its another normally opened contact ka12, the feeder ear that kd12 is connected to main current supply circuit forms self-locking structure, the 3rd non-moved end C1 connects the input of current transformer primary coil L1, the 4th non-moved end C2 connects the end over the ground of main current supply circuit through the primary coil of transformer T1, the secondary coil of transformer 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, in the embodiment of the present invention, increase the self-locking structure of the first relay, the 4th relay, can guarantee the stability of circuit operation.Double-point double-throw switch can increase the practicality of protective circuit, and it not only starts important function in realizing relay latching circuit, and can realize and directly power to the load and by too little current, detect the handoff functionality that powers to the load of protection structure.When the first moved end A1 connects the first non-moved end B1, when the 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 the normally opened contact ka34 of the first relay and the 4th relay, the startup that detects defencive function for follow-up too little current provides path to prepare, now, by the A1 of double-point double-throw switch, A2 switching is switched to C1, C2, transformer T1 makes it enter operating state as direct current supply module to the first current-amplifying device and the power supply of the second current-amplifying device, current transformer starts to be linked in main current supply circuit and enters operating state, too little current monitoring and super-high-current monitoring function are activated.
In order to be further convenient to control and regulate sampling ratio, in the embodiment of the present invention, the first secondary coil L2 and second subprime coil L3 have respectively at least one tap, one end of the 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 of the first secondary coil or a wherein tap by one first selector 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 K3 to be switched to the other end of second subprime coil or a wherein tap by one second selector switch.In different application scenarios, different to the requirement of current monitoring, can regulate by selector switch, easy to operate, simple and practical.
For further convenient operation person can understand the size of load current timely, better to regulate too little current monitoring state or super-high-current monitoring state, in main current supply circuit, be connected in series an ammeter for detection of load current size.In the embodiment of the present invention, this ammeter is connected to the front end that is positioned at load in main current supply circuit.
Feeder ear at main current supply circuit is also serially connected with fuse F, the feeder ear of main current supply circuit also connects end over the ground through a resistance R 1, a power supply indicator S1 successively, when the feeder ear of main current supply circuit accesses power supply, power supply indicator lights, and prompting operation person has power supply access.
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 to introduction.
When the feeder ear access power supply of main current supply circuit, power supply indicator S1 lights, now double-point double-throw switch switches in A1, A2 connects respectively B1, the state of B2, power supply directly powers to the load, ammeter shows load current, electric current passes through A1 successively, B1, A2, B2 drives the solenoid ka of the first relay and the solenoid kd of the 4th relay, all normally opened contacts of the first relay and the 4th relay are closed, for current transformer the first loop, primary coil place provides path, main current supply circuit feeder ear is powered to the first electromagnetic coil relay ka and the 4th 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 start too little current monitoring function and super-high-current monitoring function, switch dual double-pole double throw switch is to A1, A2 connects respectively C1, the state of C2, the electric current of the feeder ear of main current supply circuit passes through A1 successively, C1, current transformer the first primary coil, contact kd34, the parallel branch that contact kb34 and contact ka34 form 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 operating state, start the first current-amplifying device and the second current-amplifying device, the second relay and the 3rd relay enter into operating state, owing to there being normal current flowing in main current supply circuit, first level coil coupling of current transformer to electric current can be greater than the first monitoring threshold values, make the contact kb34 adhesive of the second relay, but now current transformer second subprime coil coupling to electric current can be less than the second monitoring threshold values (not over-current state), so the normally-closed contact kc34 of the 3rd relay is also 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 only kept connecting by contact kd34 and contact kb34 in main current supply circuit, now, if occur, in main current supply circuit, electric current is too small, the second relay quits work, contact kb34 disconnects, if electric current is excessive in main current supply circuit, the solenoid of the 3rd relay is driven, contact kc34 disconnects, cause the 4th relay to quit work, contact kd34 disconnects, below realize respectively the too small auto-breaking protection of electric current and the excessive auto-breaking defencive function of electric current.
The too little current automatic power-off protection circuit and the charger that above the embodiment of the present invention are provided are described in detail, applied specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment is just for helping to understand method of the present invention and core concept thereof; , for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention meanwhile.
Claims (10)
1. too little current automatic power-off protection circuit, it is characterized in that, comprise: the first relay, the second relay, current sensing means for detection of size of current in main current supply circuit sampling, for the electric current that current sensing means sampling is obtained, amplifies the first current-amplifying device of processing and for the direct current supply module of DC offset voltage is provided to the first current-amplifying device, the first relay and the second relay are serially connected in main current supply circuit after having respectively a normally opened contact and two normally opened contact parallel connections, the solenoid of the first relay is connected in series and is connected to the feeder ear of main current supply circuit after a normally closed switch and over the ground between end, the current value that current sensing means sampling obtains is greater than while setting the first monitoring threshold values, the first current-amplifying device drives the solenoid of the second relay to make the normally opened contact of the second relay closed.
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; the feeder ear of main current supply circuit connects load input terminal through the primary coil of current transformer, the parallel branch consisting of described two normally opened contacts successively, and the first secondary coil of current transformer exports through one first rectification filtering module the electric current being coupled to first current-amplifying device.
3. too little current automatic power-off protection circuit as claimed in claim 2; it is characterized in that; described the first current-amplifying device comprises: a NPN triode, the first resistance and the second resistance; the first rectification filtering module connects signal ground through the first resistance and the second resistance successively; the second resistance provides bias voltage to the base stage of a NPN triode; the emitter of the one NPN triode connects signal ground, and the collector electrode of a NPN triode is connected to the feeder ear of direct current supply module through the solenoid of described the second relay.
4. too little current automatic power-off protection circuit as claimed in claim 2; it is characterized in that, the feeder ear of main current supply circuit is selected directly to power to the load or through the primary coil of current transformer, the parallel branch consisting of described two normally opened contacts, power to the load successively through a gating switch.
5. too little current automatic power-off protection circuit as claimed in claim 2, it is characterized in that, described current sensing means also comprises: with the second subprime coil of the first primary coil coupling, the second rectification filtering module, the 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, second subprime coil exports through the second rectification filtering module the electric current being coupled to second current-amplifying device, the second current-amplifying device second subprime coil coupling to electric current surpass to set the second monitoring threshold values time drive the solenoid of the 3rd relay that the normally-closed contact of the 3rd relay is disconnected, the normally-closed contact of the solenoid of the 4th relay and the 3rd relay form a series arm be connected to the feeder ear of main current supply circuit and over the ground end between, 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 the second current-amplifying device comprises: the 2nd NPN triode, the 3rd resistance and the 4th resistance; the second rectification filtering module connects signal ground through the 3rd resistance and the 4th resistance successively; the 4th resistance provides bias voltage to the base stage of the 2nd NPN triode; the emitter of the 2nd NPN triode connects signal ground, and the collector electrode of the 2nd NPN triode is connected to the feeder ear of direct current supply module through the solenoid of described the 3rd relay.
7. too little current automatic power-off protection circuit as claimed in claim 5, it is characterized in that, also comprise double-point double-throw switch, direct current supply module comprises transformer and the 3rd rectification filtering module, double-point double-throw switch comprises 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, the first moved end A1 switches between the first non-moved end B1 and the 3rd non-moved end C1, the second moved end A2 switches between the second non-moved end B2 and the 4th non-moved end C2, the first relay and the 4th relay have respectively another normally opened contact, the first moved end A1 connects the feeder ear of main current supply circuit, the second moved end A2 and the first non-moved end B1 short circuit, the first non-moved end B1 connects load input terminal, the second non-moved end B2 is connected the end over the ground of main current supply circuit through the solenoid of the first relay successively with the series arm of normally closed switch formation, the second non-moved end B2 forms with the 3rd relay normally-closed contact the end over the ground that series arm is connected main current supply circuit through the solenoid of the 4th relay successively, the first moved end A1, when the 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 powered to the solenoid of the first relay and the 4th relay respectively, the solenoid of the first relay and the 4th relay is also connected to respectively the feeder ear formation self-locking structure of main current supply circuit by its another normally opened contact, the 3rd non-moved end C1 connects the input of current transformer primary coil, the 4th non-moved end C2 connects the end over the ground of main current supply circuit through the primary coil of transformer, the secondary coil of transformer 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, the first secondary coil and second subprime coil have respectively at least one tap, one end of the 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 of the first secondary coil or a wherein tap by one first selector 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 of second subprime coil or a wherein tap by one second selector switch.
9. too little current automatic power-off protection circuit as claimed in claim 5, is characterized in that, the first resistance and the 3rd resistance are adjustable resistance.
10. a charger, is characterized in that, comprises 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 true CN103633613A (en) | 2014-03-12 |
| CN103633613B CN103633613B (en) | 2016-06-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| 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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| Country | Link |
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| CN (1) | CN103633613B (en) |
Cited By (3)
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| CN110716421A (en) * | 2018-07-11 | 2020-01-21 | 兰州大成铁路信号有限公司 | Execution unit switching circuit, electronic execution system comprising same and switching method |
| CN112821347A (en) * | 2021-03-17 | 2021-05-18 | 广东电网有限责任公司 | Electrified current protection circuit |
| CN114373660A (en) * | 2022-01-25 | 2022-04-19 | 深圳市君安电气设备有限公司 | Intelligent circuit breaker |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110716421A (en) * | 2018-07-11 | 2020-01-21 | 兰州大成铁路信号有限公司 | Execution unit switching circuit, electronic execution system comprising same and switching method |
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| CN112821347A (en) * | 2021-03-17 | 2021-05-18 | 广东电网有限责任公司 | Electrified current protection circuit |
| CN114373660A (en) * | 2022-01-25 | 2022-04-19 | 深圳市君安电气设备有限公司 | Intelligent circuit breaker |
| CN114373660B (en) * | 2022-01-25 | 2024-02-09 | 深圳市君安电气设备有限公司 | Intelligent circuit breaker |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103633613B (en) | 2016-06-15 |
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