CN105425082A - Apparatus, method and device for detecting arc faults - Google Patents
Apparatus, method and device for detecting arc faults Download PDFInfo
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Abstract
The invention discloses equipment, a method and a device for detecting arc faults. Wherein, this equipment includes: the filter circuit is arranged on a detection line between a power supply and a load and used for filtering a current signal in the detection line to obtain a filtered current; and the arc fault detector is arranged between the filter circuit and the load and used for judging whether an arc fault is generated in the detection line or not based on the filtered current. The invention solves the technical problem of arc fault detector misoperation caused by the existence of interference signals in the prior art.
Description
Technical field
The present invention relates to arc fault field, in particular to a kind of equipment, the method and apparatus that detect arc fault.
Background technology
Arc fault detector (Arc-FaultCircuit-Interrupter, abbreviation AFCI), for preventing the power fail such as electrical appliance power cord loose contact, aging circuit sparking, to avoid causing the situation of electrical fire to occur because of circuit sparking.Existing series fault arc detection technique, ultimate principle is all adopt current transformer to detect power circuit electric current, when comprising a large amount of high-frequency signals in the power circuit electric current detected, by high-frequency signal amplitude and number quantitative analysis, determine whether arc fault occurs.
But arc fault detector product in the market exists a common problem, namely detecting device easily causes the problem of detector false action by the impact of external interference signal, by carrying out analytic explanation to Fig. 1.As shown in Figure 1; two loads (the first load 15 ' and the second load 17 ') are powered by same power supply 20 '; and run under same power supply; first load is directly connected with power supply; an arc fault detector 23 ' is arranged in series, for the protection of the working condition with monitoring second load between second load and power supply.Known by analyzing, when producing string arc fault or other undesired signals in the first loaded line, a large amount of high frequency spikes can be produced in the electric current of this circuit, in the circuit of these high frequency spikes meeting crosstalk to the second load, arc fault detector detects action tripping after these high frequency spikes, cut off the connection of the second load and power supply, like this for the second loaded line, the string arc fault in the first loaded line or other undesired signals just result in the arc fault detector misoperation in the second loaded line.
For the problem causing arc fault detector misoperation because there is undesired signal of the prior art, at present effective solution is not yet proposed.
Summary of the invention
Embodiments provide a kind of equipment, the method and apparatus that detect arc fault, at least to solve the technical matters causing arc fault detector misoperation because there is undesired signal of the prior art.
According to an aspect of the embodiment of the present invention, provide a kind of equipment detecting arc fault, this equipment comprises: filtering circuit, is arranged on the detection line between power supply and load, for carrying out filtering to the current signal in described detection line, obtain filtered electric current; Arc fault detector, is arranged between described filtering circuit and described load, for judging whether produce arc fault in described detection line based on described filtered electric current.
Further, described arc fault detector comprises: current transformer, is connected with described filtering circuit, for described filtered electric current of sampling, obtains current sampling signal; Operational amplifier, is connected with described current transformer, is amplified signal for amplifying described current sampling signal; Bandwidth filtering circuit, is connected with described operational amplifier, for filtering described amplifying signal, obtains the signal of assigned frequency band; Processor, is connected with described bandwidth filtering circuit, for determining whether produce arc fault in described detection line based on the signal of described assigned frequency band.
Further, described processor comprises: microprocessor, be connected with described bandwidth filtering circuit, for carrying out Fourier transform to the signal of described assigned frequency band, obtain the component amplitude of each frequency of the signal of described assigned frequency band, and the component amplitude of each frequency described is added up, obtain amplitude accumulated value; The size of more described amplitude accumulated value, first threshold and Second Threshold; If described amplitude accumulated value is greater than described Second Threshold, then judges in described detection line, to produce string arc fault, and generate trip signal; If described amplitude accumulated value is greater than described first threshold and is less than described Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in described detection line.
Further, described arc fault detector also comprises: disconnecting circuit, is connected with described microprocessor, for after receiving described trip signal, disconnects described power supply.
Further, described power supply is AC power, and described filtering circuit comprises: the first electric capacity, and first end is connected with the live wire of described AC power, and the second end is connected with the zero line of described AC power; Inductance, first end is connected with the first end of described first electric capacity; Second end is connected with the second end of described first electric capacity; Second electric capacity, the three-terminal link of first end and described inductance, the second end is connected with the 4th end of described inductance; The first end of described arc fault detector is connected with the first end of described second electric capacity, and the second end of described arc fault detector is connected with the second end of described second electric capacity.
Further, described inductance is common mode inductance, and described common mode inductance is the firm material of silicon.
According to the another aspect of the embodiment of the present invention, additionally provide a kind of method detecting arc fault, the method comprises: carry out filtering to the current signal in detection line between power supply and load, obtains filtered electric current; Judge whether produce arc fault in described detection line based on described filtered electric current.
Further, judge that whether producing arc fault in described detection line comprises based on described filtered electric current: described filtered electric current of sampling, obtains current sampling signal; Amplify described current sampling signal and be amplified signal; Filter described amplifying signal, obtain the signal of assigned frequency band; Signal based on described assigned frequency band determines whether produce arc fault in described detection line.
Further, the signal based on described assigned frequency band determines that whether producing arc fault in described detection line comprises: carry out Fourier transform to the signal of described assigned frequency band, obtain the component amplitude of each frequency of the signal of described assigned frequency band; The component amplitude of each frequency described is added up, obtains amplitude accumulated value; The size of more described amplitude accumulated value, first threshold and Second Threshold; If described amplitude accumulated value is greater than described Second Threshold, then judges in described detection line, to produce string arc fault, and generate trip signal; If described amplitude accumulated value is greater than described first threshold and is less than described Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in described detection line.
Further, after generation trip signal, described method also comprises: disconnect described power supply based on described trip signal.
According to the another aspect of the embodiment of the present invention, additionally provide a kind of device detecting arc fault, this device comprises: filtration module, for carrying out filtering to the current signal in detection line between power supply and load, obtains filtered electric current; Judge module, for judging whether produce arc fault in described detection line based on described filtered electric current.
Further, described judge module comprises: sampling submodule, for described filtered electric current of sampling, obtains current sampling signal; Amplifying submodule, being amplified signal for amplifying described current sampling signal; Filtering submodule, for filtering described amplifying signal, obtaining the signal of assigned frequency band; Determine submodule, for determining whether produce arc fault in described detection line based on the signal of described assigned frequency band.
In embodiments of the present invention, by increasing filtering hardware circuit in arc fault detector front end, the external interference signal that the string arc fault occurred by external loading of filtered arc fault detector front end or other undesired signals cause, judge whether arc fault occurs in circuit based on the electric current after this filtration, can effectively prevent external interference signal from producing misoperation to arc fault detector, solving the problem causing arc fault detector misoperation in prior art because there is undesired signal, enhancing the reliability of arc fault detector.
Accompanying drawing explanation
Accompanying drawing described herein is used to provide a further understanding of the present invention, and form a application's part, schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings:
Fig. 1 is a kind of schematic diagram detecting the equipment of arc fault according to prior art;
Fig. 2 is a kind of schematic diagram detecting the equipment of arc fault according to the embodiment of the present invention;
Fig. 3 is the schematic diagram of the equipment of a kind of optional detection arc fault according to the embodiment of the present invention;
Fig. 4 is a kind of process flow diagram detecting the method for arc fault according to the embodiment of the present invention;
Fig. 5 is the process flow diagram of the method for a kind of optional detection arc fault according to the embodiment of the present invention;
Fig. 6 is a kind of schematic diagram detecting the device of arc fault according to the embodiment of the present invention.
Embodiment
The present invention program is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the embodiment of a part of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, should belong to the scope of protection of the invention.
It should be noted that, term " first ", " second " etc. in instructions of the present invention and claims and above-mentioned accompanying drawing are for distinguishing similar object, and need not be used for describing specific order or precedence.Should be appreciated that the data used like this can be exchanged in the appropriate case, so as embodiments of the invention described herein can with except here diagram or describe those except order implement.In addition, term " comprises " and " having " and their any distortion, intention is to cover not exclusive comprising, such as, contain those steps or unit that the process of series of steps or unit, method, system, product or equipment is not necessarily limited to clearly list, but can comprise clearly do not list or for intrinsic other step of these processes, method, product or equipment or unit.
Fig. 2 is a kind of schematic diagram detecting the equipment of arc fault according to the embodiment of the present invention, and as shown in Figure 2, this equipment can comprise: filtering circuit 21 and arc fault detector 23.
Wherein, filtering circuit 21, is arranged on the detection line between power supply 20 and load 25, for carrying out filtering to the current signal in detection line, obtains filtered electric current.
Arc fault detector 23, is arranged between filtering circuit and load, for judging whether produce arc fault in detection line based on filtered electric current.
In the above-described embodiments, by increasing filtering hardware circuit in arc fault detector front end, the external interference signal that the string arc fault occurred by external loading of filtered arc fault detector front end or other undesired signals cause, judge whether arc fault occurs in circuit based on the electric current after this filtration, can effectively prevent external interference signal from producing misoperation to arc fault detector, solving the problem causing arc fault detector misoperation in prior art because there is undesired signal, enhancing the reliability of arc fault detector.
Pass through above-described embodiment, utilize the filtering circuit be arranged between power supply and arc fault detector, in conjunction with the software program in arc fault detector, filtered current information is carried out to the confirmation of arc fault, accurately can judge whether produce arc fault in detection line.
Particularly, between power supply and arc fault detector, filtering circuit is set, by this filtering circuit, filtering is carried out to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, and whether produce fault by the software program in arc fault detector based in filtered electric current determination detection line.
Above-mentioned arc fault detector AFCI is for the protection of connected backend load; particularly; on detection line between power supply and backend load or backend load generation arc fault time, arc fault detector disconnects and being connected with the energising of power supply, reaches and protects backend load effect.If arc fault detector front end is without any filtering, then this arc fault detector is easily subject to the impact of external interference signal and causes its misoperation.Therefore the present invention adds hardware filtering circuit in arc fault detector front end, the external interference signal caused by external loading appearance string arc fault or other undesired signals with abatement is on the impact of arc fault detector, and can prevent arc fault detector rear end from externally producing noise, there is good electromagnetic compatibility (ElectroMagneticCompatibility, abbreviation EMC) effect, strengthen arc fault detector reliability.
In the above embodiment of the present invention, arc fault detector can comprise: current transformer, is connected with filtering circuit, for the electric current after sampling filter, obtains current sampling signal; Operational amplifier, is connected with current transformer, is amplified signal for amplified current sampled signal; Bandwidth filtering circuit, is connected with operational amplifier, for filtering amplifying signal, obtains the signal of assigned frequency band; Processor, is connected with bandwidth filtering circuit, for whether producing arc fault based in the signal determination detection line of assigned frequency band.
Particularly, filtering circuit carries out filtering to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, current transformer connects in filtering circuit rear end, to sample this filtered electric current, obtain current sampling signal, this current sampling signal is raised through operational amplifier, amplify, be amplified signal, bandwidth filtering circuit again by being built by operational amplifier, this amplifying signal is carried out filtering, obtain the signal of assigned frequency band, and by the analog-digital conversion a/d interface of the processor of the signal of this assigned frequency band input arc fault detector AFCI, whether arc fault is produced based in the signal determination detection line of assigned frequency band by software program.
Pass through above-described embodiment, obtain the signal of assigned frequency band in the filtered electric current on detection line, this assigned frequency band covers each frequency that arc fault may occur, by the signal determination arc fault of assigned frequency band, while reduction calculated amount, the accuracy determining arc fault can be ensured.
In the above embodiment of the present invention, processor can comprise: microprocessor, be connected with bandwidth filtering circuit, for carrying out Fourier transform to the signal of assigned frequency band, obtain the component amplitude of each frequency of the signal of assigned frequency band, and the component amplitude of each frequency is added up, obtain amplitude accumulated value; The relatively size of amplitude accumulated value, first threshold and Second Threshold; If amplitude accumulated value is greater than Second Threshold, then judges in detection line, to produce string arc fault, and generate trip signal; If amplitude accumulated value is greater than first threshold and is less than Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in detection line.Alternatively, preset time period can be 1s, and predetermined number can pre-set.
Further, arc fault detector can also comprise: disconnecting circuit, is connected with microprocessor, for after receiving trip signal, and deenergization.
Particularly, the analog-digital conversion a/d interface of the processor (microprocessor described above) of arc fault detector AFCI to assigned frequency band signal after, main control microprocessor (the namely above-mentioned microprocessor) signal to this assigned frequency band carries out Fast Fourier Transform (FFT) (FastFourierTransformation, abbreviation FFT), obtain the component amplitude of each frequency of the signal of assigned frequency band, the component amplitude of each frequency is added up, obtains amplitude accumulated value; If amplitude accumulated value is greater than protection threshold value (namely above-mentioned Second Threshold); then judge in detection line, to produce string arc fault; main control microprocessor sends high level trip signal, and this high level takes off message number and acts on disconnecting circuit (as isolating switch), tripping power supply.If amplitude accumulated value is greater than normality threshold (namely above-mentioned first threshold) and is less than protection threshold value, then statistical number n (n represents the doubtful signal number of above-mentioned crosstalk) is added 1, if the numerical value of statistical number n is greater than with reference to number N (namely above-mentioned predetermined number) in 1s, then judge to occur crosstalk signal in detection line, main control microprocessor does not then send high level trip signal; If the numerical value of statistical number n is not more than with reference to number N in 1s, then main control microprocessor returns the magnitude relationship judging amplitude accumulated value and normality threshold and protect threshold value.
By above-described embodiment, by the signal of assigned frequency band that obtains by the computing of main control microprocessor, judge whether produce arc fault in detection line based on result of calculation.By the scheme that hardware filtering circuit combines with software program, accurately judge whether detection line arc fault occurs, thus reach the object of the generation reducing arc fault detector misoperation situation.
As shown in Figure 3, power supply 20 can be AC power AC, and above-mentioned filtering circuit can comprise: the first electric capacity C1, and first end is connected with the live wire L of AC power AC, and the second end is connected with the zero line N of AC power AC; Inductance L, first end is connected with the first end of the first electric capacity C1; Second end is connected with second end of the first electric capacity C1; Second electric capacity C2, the three-terminal link of first end and inductance L, the second end is connected with the 4th end of inductance L; The first end of arc fault detector 23 is connected with the first end of the second electric capacity C2, and the second end of arc fault detector 23 is connected with second end of the second electric capacity C2.Inductance in Fig. 3 can be common mode inductance, and the first end of this common mode inductance represents by numeral 1 to 4 respectively to the 4th end, and this common mode inductance is the firm material of silicon.
As shown in Figure 3, arc fault detector 23 comprises four ports, and the 3rd end is wherein connected with the first end of load 25, and the 4th end of arc fault detector 23 is connected with the second end of load 25, and this first end also can represent by numeral 1 to 4 respectively to the 4th end.
Below for dehumidifier or air conditioner as load, composition graphs 3 describes the embodiment of the present invention in detail:
At dehumidifier or air conditioner as in the application of load, the crosstalk signal in detection line is altogether/differential mode noise signal.As shown in Figure 3, filtering circuit is made up of the first electric capacity C1, the second electric capacity C2 and inductance L, and L can be common mode inductance, and its property value can be 5mH/10A, for eliminating common mode noise signal; But in actual applications, the inductance value not necessarily full symmetric of common mode inductance two coils, differential mode inductance is formed in the asymmetric situation of the inductance value of two coils, this differential mode inductance and the acting in conjunction of X electric capacity, for eliminating differential mode noise signal, wherein, X electric capacity is the electric capacity be connected between the zero line of AC power and live wire, as the first electric capacity C1 in Fig. 3 and the second electric capacity C2, the property value of two electric capacity can be 1 μ f; Above-mentioned common mode inductance L can adopt silicon steel material, compared with common mode inductance of the prior art, can reduce the area taking printed-wiring board (PWB) (PrintedCircuitBoard, abbreviation PCB) when reaching same effect.
Alternatively, the current signal in the detection line that can test according to reality of the X electric capacity of above-mentioned composition filtering circuit and the property value of common mode inductance L carries out type selecting adjustment.In addition, for making the filter effect of filtering circuit reach best, filtering circuit can be integrated on a pcb board with arc fault detector, also can take two plate form, specifically can carry out layout according to production, structure installment mode.
By above-described embodiment, above-mentioned filtering circuit is set in arc fault detector front end, filters out the undesired signal of arc fault detector front end, thus the problem causing arc fault detector misoperation because there is undesired signal of the prior art can be solved.
Pass through the above embodiment of the present invention, filtering circuit is increased in the hardware circuit front end of arc fault detector AFCI, with the string arc fault or other undesired signals of cutting down external loading appearance, the misoperation of arc fault detector is disturbed, and can prevent the rear end of arc fault detector from externally producing noise by this filtering circuit.Meanwhile, the present invention is based on the filtering circuit of hardware circuit and combining of software program, solve the generation of arc fault detector misoperation situation further, enhance the accuracy that arc fault detector detects.
According to the embodiment of the present invention, provide a kind of embodiment detecting the method for arc fault, it should be noted that, can perform in the computer system of such as one group of computer executable instructions in the step shown in the process flow diagram of accompanying drawing, and, although show logical order in flow charts, in some cases, can be different from the step shown or described by order execution herein.
Fig. 4 is a kind of process flow diagram detecting the method for arc fault according to the embodiment of the present invention, and as shown in Figure 4, the method comprises the steps:
Step S402, carries out filtering to the current signal in detection line between power supply and load, obtains filtered electric current.
Step S404, judges whether produce arc fault in detection line based on filtered electric current.
Adopt embodiments of the invention, by increasing filtering hardware circuit in arc fault detector front end, the external interference signal that the string arc fault occurred by external loading of filtered arc fault detector front end or other undesired signals cause, judge whether arc fault occurs in circuit based on the electric current after this filtration, can effectively prevent external interference signal from producing misoperation to arc fault detector, solving the problem causing arc fault detector misoperation in prior art because there is undesired signal, enhancing the reliability of arc fault detector.
Pass through above-described embodiment, utilize the filtering circuit be arranged between power supply and arc fault detector, in conjunction with the software program in arc fault detector, filtered current information is carried out to the confirmation of arc fault, accurately can judge whether produce arc fault in detection line.
Particularly, between power supply and arc fault detector, filtering circuit is set, by this filtering circuit, filtering is carried out to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, and whether produce fault by the software program in arc fault detector based in filtered electric current determination detection line.
Above-mentioned arc fault detector AFCI is for the protection of connected backend load; particularly; on detection line between power supply and backend load or backend load generation arc fault time, arc fault detector disconnects and being connected with the energising of power supply, reaches and protects backend load effect.If arc fault detector front end is without any filtering, then this arc fault detector is easily subject to the impact of external interference signal and causes its misoperation.Therefore the present invention adds hardware filtering circuit in arc fault detector front end, the external interference signal caused by external loading appearance string arc fault or other undesired signals with abatement is on the impact of arc fault detector, and can prevent arc fault detector rear end from externally producing noise, there is good electromagnetic compatibility (ElectroMagneticCompatibility, abbreviation EMC) effect, strengthen arc fault detector reliability.
In the above embodiment of the present invention, judge that whether producing arc fault in detection line comprises based on filtered electric current: the electric current after sampling filter, obtains current sampling signal; Amplified current sampled signal is amplified signal; Filter amplifying signal, obtain the signal of assigned frequency band; Whether arc fault is produced based in the signal determination detection line of assigned frequency band.
Particularly, filtering circuit carries out filtering to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, current transformer connects in filtering circuit rear end, to sample this filtered electric current, obtain current sampling signal, this current sampling signal is raised through operational amplifier, amplify, be amplified signal, bandwidth filtering circuit again by being built by operational amplifier, this amplifying signal is carried out filtering, obtain the signal of assigned frequency band, and by the analog-digital conversion a/d interface of the processor of the signal of this assigned frequency band input arc fault detector AFCI, whether arc fault is produced based in the signal determination detection line of assigned frequency band by software program.
Pass through above-described embodiment, obtain the signal of assigned frequency band in the filtered electric current on detection line, this assigned frequency band covers each frequency that arc fault may occur, by the signal determination arc fault of assigned frequency band, while reduction calculated amount, the accuracy determining arc fault can be ensured.
In the above embodiment of the present invention, based on whether producing arc fault in the signal determination detection line of assigned frequency band comprise: Fourier transform is carried out to the signal of assigned frequency band, obtains the component amplitude of each frequency of the signal of assigned frequency band; The component amplitude of each frequency is added up, obtains amplitude accumulated value; The relatively size of amplitude accumulated value, first threshold and Second Threshold; If amplitude accumulated value is greater than Second Threshold, then judges in detection line, to produce string arc fault, and generate trip signal; If amplitude accumulated value is greater than first threshold and is less than Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in detection line.Alternatively, preset time period can be 1s, and predetermined number can pre-set.
Further, after generation trip signal, the method can also comprise: based on trip signal deenergization.
Particularly, the analog-digital conversion a/d interface of the processor (microprocessor described above) of arc fault detector AFCI to assigned frequency band signal after, main control microprocessor (the namely above-mentioned microprocessor) signal to this assigned frequency band carries out Fast Fourier Transform (FFT) (FastFourierTransformation, abbreviation FFT), obtain the component amplitude of each frequency of the signal of assigned frequency band, the component amplitude of each frequency is added up, obtains amplitude accumulated value; If amplitude accumulated value is greater than protection threshold value (namely above-mentioned Second Threshold); then judge in detection line, to produce string arc fault; main control microprocessor sends high level trip signal, and this high level takes off message number and acts on disconnecting circuit (as isolating switch), tripping power supply.If amplitude accumulated value is greater than normality threshold (namely above-mentioned first threshold) and is less than protection threshold value, then statistical number n (n represents the doubtful signal number of above-mentioned crosstalk) is added 1, if the numerical value of statistical number n is greater than with reference to number N (namely above-mentioned predetermined number) in 1s, then judge to occur crosstalk signal in detection line, main control microprocessor does not then send high level trip signal; If the numerical value of statistical number n is not more than with reference to number N in 1s, then main control microprocessor returns the magnitude relationship judging amplitude accumulated value and normality threshold and protect threshold value.
Below in conjunction with Fig. 5 in detail embodiments of the invention are described in detail, as shown in Figure 5, this embodiment can comprise the steps:
Step S501, carries out filtering by filtering circuit to the current signal in the detection line between power supply and load, obtains filtered electric current.
Step S502, the electric current after sampling filter, and filtered electric current is amplified and filters, obtain the signal of assigned frequency band.
Step S503, by the analog-digital conversion a/d interface of the microprocessor of the signal of assigned frequency band input arc fault detector.
Step S504, microprocessor carries out Fast Fourier Transform (FFT) to the signal of assigned frequency band, obtains the component amplitude of each frequency of the signal of assigned frequency band.
Step S505, adds up the component amplitude of each frequency, obtains amplitude accumulated value.
Step S506, judges whether amplitude accumulated value is greater than normality threshold and is less than protection threshold value.
If judge, amplitude accumulated value is greater than normality threshold and is less than protection threshold value, then perform step S507; Otherwise, perform step S510.
Step S507, adds 1 by statistical number n.
Wherein, n represents the doubtful signal number of above-mentioned crosstalk.
Step S508, judges whether the numerical value of statistical number n in 1s is greater than with reference to number N.
If judge, in 1s, the numerical value of statistical number n is greater than with reference to number N, then perform step S509; Otherwise, return and perform step S506.
Step S509, judges to occur crosstalk signal in detection line.
Step S510, judges whether amplitude accumulated value is greater than protection threshold value.
If judge, amplitude accumulated value is greater than protection threshold value, then perform step S511; Otherwise, return and perform step S506.
Step S511, judges to produce string arc fault in detection line, and sends high level trip signal by microprocessor.
Step S512, takes off message disconnection disconnecting circuit, with deenergization based on high level.
By above-described embodiment, by the signal of assigned frequency band that obtains by the computing of main control microprocessor, judge whether produce arc fault in detection line based on result of calculation.By the scheme that hardware filtering circuit combines with software program, accurately judge whether detection line arc fault occurs, thus reach the object of the generation reducing arc fault detector misoperation situation.
Pass through the above embodiment of the present invention, filtering circuit is increased in the hardware circuit front end of arc fault detector AFCI, with the string arc fault or other undesired signals of cutting down external loading appearance, the misoperation of arc fault detector is disturbed, and can prevent the rear end of arc fault detector from externally producing noise by this filtering circuit.Meanwhile, the present invention is based on the filtering circuit of hardware circuit and combining of software program, solve the generation of arc fault detector misoperation situation further, enhance the accuracy that arc fault detector detects.
Fig. 6 is a kind of schematic diagram detecting the device of arc fault according to the embodiment of the present invention, and as shown in Figure 6, this device can comprise: filtration module 61 and judge module 63.
Wherein, filtration module 61, for carrying out filtering to the current signal in detection line between power supply and load, obtains filtered electric current.
Judge module 63, for judging whether produce arc fault in detection line based on filtered electric current.
Adopt embodiments of the invention, by increasing filtering hardware circuit in arc fault detector front end, the external interference signal that the string arc fault occurred by external loading of filtered arc fault detector front end or other undesired signals cause, judge whether arc fault occurs in circuit based on the electric current after this filtration, can effectively prevent external interference signal from producing misoperation to arc fault detector, solving the problem causing arc fault detector misoperation in prior art because there is undesired signal, enhancing the reliability of arc fault detector.
Pass through above-described embodiment, utilize the filtering circuit be arranged between power supply and arc fault detector, in conjunction with the software program in arc fault detector, filtered current information is carried out to the confirmation of arc fault, accurately can judge whether produce arc fault in detection line.
Particularly, between power supply and arc fault detector, filtering circuit is set, by this filtering circuit, filtering is carried out to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, and whether produce fault by the software program in arc fault detector based in filtered electric current determination detection line.
Above-mentioned arc fault detector AFCI is for the protection of connected backend load; particularly; on detection line between power supply and backend load or backend load generation arc fault time, arc fault detector disconnects and being connected with the energising of power supply, reaches and protects backend load effect.If arc fault detector front end is without any filtering, then this arc fault detector is easily subject to the impact of external interference signal and causes its misoperation.Therefore the present invention adds hardware filtering circuit in arc fault detector front end, the external interference signal caused by external loading appearance string arc fault or other undesired signals with abatement is on the impact of arc fault detector, and can prevent arc fault detector rear end from externally producing noise, there is good electromagnetic compatibility (ElectroMagneticCompatibility, abbreviation EMC) effect, strengthen arc fault detector reliability.
In the above embodiment of the present invention, judge module can comprise: sampling submodule, for the electric current after sampling filter, obtains current sampling signal; Amplify submodule, be amplified signal for amplified current sampled signal; Filtering submodule, for filtering amplifying signal, obtaining the signal of assigned frequency band; Determine submodule, for whether producing arc fault based in the signal determination detection line of assigned frequency band.
Particularly, filtering circuit carries out filtering to the current signal in the detection line of arc fault detector front end, obtain filtered electric current, current transformer connects in filtering circuit rear end, to sample this filtered electric current, obtain current sampling signal, this current sampling signal is raised through operational amplifier, amplify, be amplified signal, bandwidth filtering circuit again by being built by operational amplifier, this amplifying signal is carried out filtering, obtain the signal of assigned frequency band, and by the analog-digital conversion a/d interface of the processor of the signal of this assigned frequency band input arc fault detector AFCI, whether arc fault is produced based in the signal determination detection line of assigned frequency band by software program.
Pass through above-described embodiment, obtain the signal of assigned frequency band in the filtered electric current on detection line, this assigned frequency band covers each frequency that arc fault may occur, by the signal determination arc fault of assigned frequency band, while reduction calculated amount, the accuracy determining arc fault can be ensured.
Pass through the above embodiment of the present invention, filtering circuit is increased in the hardware circuit front end of arc fault detector AFCI, with the string arc fault or other undesired signals of cutting down external loading appearance, the misoperation of arc fault detector is disturbed, and can prevent the rear end of arc fault detector from externally producing noise by this filtering circuit.Meanwhile, the present invention is based on the filtering circuit of hardware circuit and combining of software program, solve the generation of arc fault detector misoperation situation further, enhance the accuracy that arc fault detector detects.
The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
In the above embodiment of the present invention, the description of each embodiment is all emphasized particularly on different fields, in certain embodiment, there is no the part described in detail, can see the associated description of other embodiments.
In several embodiments that the application provides, should be understood that, disclosed technology contents, the mode by other realizes.Wherein, device embodiment described above is only schematic, the such as division of described unit, can be that a kind of logic function divides, actual can have other dividing mode when realizing, such as multiple unit or assembly can in conjunction with or another system can be integrated into, or some features can be ignored, or do not perform.Another point, shown or discussed coupling each other or direct-coupling or communication connection can be by some interfaces, and the indirect coupling of unit or module or communication connection can be electrical or other form.
The described unit illustrated as separating component or can may not be and physically separates, and the parts as unit display can be or may not be physical location, namely can be positioned at a place, or also can be distributed on multiple unit.Some or all of unit wherein can be selected according to the actual needs to realize the object of the present embodiment scheme.
In addition, each functional unit in each embodiment of the present invention can be integrated in a processing unit, also can be that the independent physics of unit exists, also can two or more unit in a unit integrated.Above-mentioned integrated unit both can adopt the form of hardware to realize, and the form of SFU software functional unit also can be adopted to realize.
If described integrated unit using the form of SFU software functional unit realize and as independently production marketing or use time, can be stored in a computer read/write memory medium.Based on such understanding, the part that technical scheme of the present invention contributes to prior art in essence in other words or all or part of of this technical scheme can embody with the form of software product, this computer software product is stored in a storage medium, comprises all or part of step of some instructions in order to make a computer equipment (can be personal computer, server or the network equipment etc.) perform method described in each embodiment of the present invention.And aforesaid storage medium comprises: USB flash disk, ROM (read-only memory) (ROM, Read-OnlyMemory), random access memory (RAM, RandomAccessMemory), portable hard drive, magnetic disc or CD etc. various can be program code stored medium.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (12)
1. detect an equipment for arc fault, it is characterized in that, comprising:
Filtering circuit, is arranged on the detection line between power supply and load, for carrying out filtering to the current signal in described detection line, obtains filtered electric current;
Arc fault detector, is arranged between described filtering circuit and described load, for judging whether produce arc fault in described detection line based on described filtered electric current.
2. equipment according to claim 1, is characterized in that, described arc fault detector comprises:
Current transformer, is connected with described filtering circuit, for described filtered electric current of sampling, obtains current sampling signal;
Operational amplifier, is connected with described current transformer, is amplified signal for amplifying described current sampling signal;
Bandwidth filtering circuit, is connected with described operational amplifier, for filtering described amplifying signal, obtains the signal of assigned frequency band;
Processor, is connected with described bandwidth filtering circuit, for determining whether produce arc fault in described detection line based on the signal of described assigned frequency band.
3. equipment according to claim 2, is characterized in that, described processor comprises:
Microprocessor, being connected with described bandwidth filtering circuit, for carrying out Fourier transform to the signal of described assigned frequency band, obtaining the component amplitude of each frequency of the signal of described assigned frequency band, and the component amplitude of each frequency described is added up, obtain amplitude accumulated value; The size of more described amplitude accumulated value, first threshold and Second Threshold; If described amplitude accumulated value is greater than described Second Threshold, then judges in described detection line, to produce string arc fault, and generate trip signal; If described amplitude accumulated value is greater than described first threshold and is less than described Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in described detection line.
4. equipment according to claim 3, is characterized in that, described arc fault detector also comprises:
Disconnecting circuit, is connected with described microprocessor, for after receiving described trip signal, disconnects described power supply.
5. equipment according to claim 1, is characterized in that, described power supply is AC power, and described filtering circuit comprises:
First electric capacity, first end is connected with the live wire of described AC power, and the second end is connected with the zero line of described AC power;
Inductance, first end is connected with the first end of described first electric capacity; Second end is connected with the second end of described first electric capacity;
Second electric capacity, the three-terminal link of first end and described inductance, the second end is connected with the 4th end of described inductance;
The first end of described arc fault detector is connected with the first end of described second electric capacity, and the second end of described arc fault detector is connected with the second end of described second electric capacity.
6. equipment according to claim 5, is characterized in that, described inductance is common mode inductance, and described common mode inductance is the firm material of silicon.
7. detect a method for arc fault, it is characterized in that, comprising:
Filtering is carried out to the current signal in detection line between power supply and load, obtains filtered electric current;
Judge whether produce arc fault in described detection line based on described filtered electric current.
8. method according to claim 7, is characterized in that, judges that whether producing arc fault in described detection line comprises based on described filtered electric current:
To sample described filtered electric current, obtain current sampling signal;
Amplify described current sampling signal and be amplified signal;
Filter described amplifying signal, obtain the signal of assigned frequency band;
Signal based on described assigned frequency band determines whether produce arc fault in described detection line.
9. method according to claim 8, is characterized in that, the signal based on described assigned frequency band determines that whether producing arc fault in described detection line comprises:
Fourier transform is carried out to the signal of described assigned frequency band, obtains the component amplitude of each frequency of the signal of described assigned frequency band;
The component amplitude of each frequency described is added up, obtains amplitude accumulated value;
The size of more described amplitude accumulated value, first threshold and Second Threshold;
If described amplitude accumulated value is greater than described Second Threshold, then judges in described detection line, to produce string arc fault, and generate trip signal;
If described amplitude accumulated value is greater than described first threshold and is less than described Second Threshold, then the numerical value of doubtful for crosstalk signal number is added one, if the doubtful signal number of the crosstalk of recording in preset time period is greater than predetermined number, then judge to occur crosstalk signal in described detection line.
10. method according to claim 9, is characterized in that, after generation trip signal, described method also comprises:
Described power supply is disconnected based on described trip signal.
11. 1 kinds of devices detecting arc fault, is characterized in that, comprising:
Filtration module, for carrying out filtering to the current signal in detection line between power supply and load, obtains filtered electric current;
Judge module, for judging whether produce arc fault in described detection line based on described filtered electric current.
12. devices according to claim 11, is characterized in that, described judge module comprises:
Sampling submodule, for described filtered electric current of sampling, obtains current sampling signal;
Amplifying submodule, being amplified signal for amplifying described current sampling signal;
Filtering submodule, for filtering described amplifying signal, obtaining the signal of assigned frequency band;
Determine submodule, for determining whether produce arc fault in described detection line based on the signal of described assigned frequency band.
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