CN104459291A - Method and system for detecting AC signals of specific frequency - Google Patents
Method and system for detecting AC signals of specific frequency Download PDFInfo
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- CN104459291A CN104459291A CN201410776707.1A CN201410776707A CN104459291A CN 104459291 A CN104459291 A CN 104459291A CN 201410776707 A CN201410776707 A CN 201410776707A CN 104459291 A CN104459291 A CN 104459291A
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Abstract
The invention discloses a method for detecting AC signals of a specific frequency. The method comprises the steps that a hollow coil is used for filtering direct current which is used for supplying power in an electric locomotive, and AC signals in the direct current are extracted; an AC amplifying circuit is used for amplifying the AC signals; and a filter circuit is used for filtering the amplified AC signals, and the AC signals of the specific frequency are obtained. The method can accurately detect the AC signals of the specific frequency in the direct current.
Description
Technical field
The present invention relates to electronic technology field, particularly relate to a kind of method and system detecting characteristic frequency AC signal.
Background technology
At direct current supply locomotive, or double fluid and multithread locomotive in DC current in often can there are some AC signal.The existence of these AC signal can cause cab signal system to be interfered, and directly can have influence on the security of operation of locomotive like this.
In existing detection DC current, the method for the AC signal of characteristic frequency utilizes high-speed computer Real-Time Monitoring locomotive specific currents amplitude (such as 50HZ current amplitude); Or adopt locomotive vehicle-mounted real-time monitoring of computer locomotive specific currents amplitude (such as 50HZ current amplitude).
But utilize the requirement of the method for high-speed computer Real-Time Monitoring locomotive to processor and computing machine very high, can cause that cost is high, volume is large, but precision can't reach requirement, can not meet the requirement of existing application; Utilize the method for locomotive vehicle-mounted real-time monitoring of computer locomotive, be locomotive vehicle-mounted computer system due to what adopt, therefore there is sample rate slow, precision is low, can not meet protection precision, therefore often occur misoperation.
Therefore, the AC signal of characteristic frequency in DC current how accurately being detected, is those skilled in the art's technical issues that need to address.
Summary of the invention
The object of this invention is to provide a kind of method detecting characteristic frequency AC signal, the method accurately can detect the AC signal of characteristic frequency in amplitude DC current, ensures the normal operation of cab signal system; Another object of the present invention is to provide a kind of system detecting characteristic frequency AC signal.
For solving the problems of the technologies described above, the invention provides a kind of method detecting characteristic frequency AC signal and comprising:
By air core coil, filtering is carried out to the DC current of powering in electric locomotive, extract the AC signal in described DC current;
By ac amplifier circuit, described AC signal is amplified;
By filtering circuit, filtering process is carried out to the AC signal after amplification, obtain the AC signal of characteristic frequency.
Wherein, the described AC signal of described extraction comprises:
When there is AC signal in DC current, the two ends output AC voltage signal of air core coil;
Utilize voltage integrator to process described ac voltage signal, obtain ac current signal.
Wherein, described by filtering circuit to amplify after AC signal carry out filtering process, the AC signal obtaining characteristic frequency comprises:
Utilize the high-pass filtering circuit of 0Hz ~ 49.5Hz to carry out filtering to the AC signal after described amplification, obtain the AC signal of more than 49.5Hz;
Utilize the low-pass filter circuit being greater than 50.5Hz to carry out filtering to the AC signal of described more than 49.5Hz, obtain the AC signal of 49.5Hz ~ 50.5Hz.
Described obtain the AC signal of characteristic frequency after also comprise:
The AC signal of described characteristic frequency is converted to by translation circuit the direct current signal that truck-mounted computer can identify;
Truck-mounted computer is monitored described direct current signal, and when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
Wherein, describedly the AC signal of described characteristic frequency be converted to by translation circuit the direct current signal that truck-mounted computer can identify comprise:
The AC signal of described characteristic frequency is converted to direct current signal by full-bridge rectification translation circuit;
Described direct current signal is transformed to through dc chopper DC/DC the DC current signal that truck-mounted computer can identify.
Wherein, when the characteristic frequency detected is the AC signal of 49.5Hz ~ 50.5Hz, described truck-mounted computer performs corresponding operation by preset program and comprises:
If described direct current signal reaches predetermined condition, truck-mounted computer will control direct current quick breaker and disconnect.
A kind of system detecting characteristic frequency AC signal provided by the present invention comprises:
Air core coil, for carrying out filtering to the DC current of powering in electric locomotive, makes, when there is AC signal in DC current, to extract described AC signal;
Amplifying circuit, for amplifying described AC signal;
Filtering circuit, carries out filtering process to the AC signal after amplifying, obtains the AC signal of characteristic frequency.
Wherein, the system detecting characteristic frequency AC signal also comprises:
Change-over circuit, for being converted to the direct current signal that truck-mounted computer can identify by the AC signal of characteristic frequency;
Truck-mounted computer, for monitoring described direct current signal, when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
Wherein, described change-over circuit comprises: dc chopper DC/DC, for direct current signal being transformed to the DC current signal that truck-mounted computer can identify.
Wherein, the system detecting characteristic frequency AC signal also comprises:
Voltage integrator, processes for the ac voltage signal extracted air core coil, obtains ac current signal.
Based on technique scheme, the method for detection characteristic frequency AC signal provided by the present invention, carries out filtering by air core coil to the DC current of powering in electric locomotive, extracts the AC signal in described DC current; By ac amplifier circuit, described AC signal is amplified; By filtering circuit, filtering process is carried out to the AC signal after amplification, obtain the AC signal of characteristic frequency; Through the filtering of air core coil to direct current carrier, when there is not AC signal in DC current, magnetic field in air core coil can not change, air core coil two ends can not produce voltage, when there is AC signal in DC current, magnetic field in air core coil can change, and air core coil two ends can produce AC signal, extracts described AC signal; Because this AC signal is very faint, therefore need to be amplified described AC signal by amplifying circuit; AC signal after amplification being carried out to the filtering circuit of characteristic frequency, when there is the AC signal of described characteristic frequency in this AC signal, the AC signal of this characteristic frequency can be obtained; The method accurately can detect the AC signal of characteristic frequency in DC current, and the method cost is low, convenient and easy.
Accompanying drawing explanation
In order to the technical scheme of the clearer explanation embodiment of the present invention or prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
The process flow diagram of the method for the detection characteristic frequency AC signal that Fig. 1 provides for the embodiment of the present invention;
The schematic diagram by air core coil, the DC current of powering in electric locomotive being carried out to filtering that Fig. 2 provides for the embodiment of the present invention;
The schematic diagram of limit, the electric locomotive Central Plains current signal before air core coil that Fig. 3 provides for the embodiment of the present invention;
The schematic diagram by air core coil, the DC current of powering in electric locomotive being carried out to filtered result that Fig. 4 provides for the embodiment of the present invention;
The method flow diagram of the described AC signal of extraction that Fig. 5 provides for the embodiment of the present invention;
The voltage integrator that utilizes that Fig. 6 provides for the embodiment of the present invention processes described ac voltage signal, obtains the schematic diagram of ac current signal;
The transition diagram of the truck-mounted computer that Fig. 7 provides for the embodiment of the present invention;
The structured flowchart of the system of the detection characteristic frequency AC signal that Fig. 8 provides for the embodiment of the present invention;
The filtering circuit schematic diagram of acquisition 49.5HZ ~ 50.5HZ AC signal that Fig. 9 provides for the embodiment of the present invention;
The structural representation of the voltage integrator that Figure 10 provides for the embodiment of the present invention;
49.5HZ ~ 50.5HZ AC signal that Figure 11 provides for the embodiment of the present invention arrives the circuit diagram of truck-mounted computer by change-over circuit.
Embodiment
The object of this invention is to provide a kind of method detecting characteristic frequency AC signal, the method accurately can detect the AC signal of characteristic frequency in amplitude DC current, ensures the normal operation of cab signal system; Another object of the present invention is to provide a kind of system detecting characteristic frequency AC signal.
For making the object of the embodiment of the present invention, technical scheme and advantage clearly, 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 the present invention's part embodiment, 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, belong to the scope of protection of the invention.
In current electric locomotive, DC power station 6 pulse wave or 12 Pulses Rectifier faults can cause the electric current and the circuit locomotive spontaneous generation characteristic frequency electric current that produce characteristic frequency, and the AC signal of these characteristic frequency can affect to the signal system of electric locomotive.Therefore electric locomotive needs the AC signal that these characteristic frequency accurately can be detected, and when the AC signal of these characteristic frequency reaches certain degree, electric locomotive needs to take appropriate measures the security of operation ensureing electric locomotive.Again because DC rated current in electric locomotive DC power-supply system is up to 2000A, but the AC signal that the inside may produce is again very faint, therefore very high to the accuracy requirement of DC current sensor and truck-mounted computer etc.Existing equipment can not meet accuracy requirement.On the basis of precision not changing these equipment, the AC signal of characteristic frequency in amplitude DC current can be detected accurately by the method for detection characteristic frequency AC signal of the present invention.
Please refer to Fig. 1, the process flow diagram of the method for the detection characteristic frequency AC signal that Fig. 1 provides for the embodiment of the present invention; The method can comprise:
Step s100, by air core coil, filtering is carried out to the DC current of powering in electric locomotive, extract the AC signal in described DC current;
Wherein, because DC rated current in electric locomotive DC power-supply system is up to 2000A, but the AC signal that the inside may produce is again very faint, and the collection therefore will carrying out AC signal on the basis of so big current is very difficult; Therefore the present invention adopts air core coil the DC current of amplitude to be filtered out, and when there is AC signal in this DC current, this AC signal can be extracted again.
AC signal in the DC current of such as, powering in electric locomotive carries out extraction can as shown in Figure 2, the schematic diagram by air core coil, the DC current of powering in electric locomotive being carried out to filtering that Fig. 2 provides for the embodiment of the present invention;
Wherein, when DC current is by electric wire, the magnetic field around air core coil is unchanged, and therefore coil two ends can not produce voltage output.
When there is alternating component in DC current, air core coil magnetic field changes, and coil two ends synchronously produce alternating voltage and export, and its output voltage is:
By adopting electrical current carriers to filter amplitude DC current by air core coil, synchronously restore the alternating component of current DC system.Wherein, the schematic diagram of limit, the electric locomotive Central Plains current signal before air core coil that provides for the embodiment of the present invention of Fig. 3; The schematic diagram by air core coil, the DC current of powering in electric locomotive being carried out to filtered result that Fig. 4 provides for the embodiment of the present invention.Can be clearly seen that by this two width figure the treatment effect utilizing air core coil, by whole for direct current signal filtering, extract AC signal.
Wherein, preferably, the parameter of air core coil can be set to:
The air core coil number of turn: 2800
Air core coil center of circle radius: 100mm
Air core coil radius: 8mm
Step s110, by ac amplifier circuit, described AC signal to be amplified;
Wherein, can see that the AC signal extracted is very faint by Fig. 4, therefore be easy to be interfered and also inconvenient follow-up process, when directly carrying out follow-up process, also need the instrument that precision is very high, and treatment effect also cannot ensure; Therefore can be amplified described AC signal by ac amplifier circuit; So namely, prevent feeble signal by external interference, make again subsequent treatment convenient.
Step s120, by filtering circuit to amplify after AC signal carry out filtering process, obtain the AC signal of characteristic frequency.
Wherein, filtering process is carried out to the AC signal after amplifying; because be not have the AC signal of frequency to be all can crisis electric locomotive security of operation, there is the AC signal of some frequencies not affect electric locomotive more, therefore unnecessaryly it to be monitored or other process.Such as, but the AC signal of some characteristic frequency just must be able to accurately detect, and processes, monitors it, prevent it from threatening to the operation of electric locomotive so that follow-up to it.The AC signal of such as 50HZ can cause interference to the signal system of electric locomotive, affects the normal operation of electric locomotive.Just filtering circuit must can be utilized accurately to detect the AC signal that whether there is 50HZ in this AC signal, when it is present, accurately must can detect, and obtain this AC signal, so that follow-up, it be monitored.To ensure the safe operation of electric locomotive.
Based on technique scheme, the method of the detection characteristic frequency AC signal that the embodiment of the present invention provides, through the filtering of air core coil to direct current carrier, when there is not AC signal in DC current, the magnetic field in air core coil can not change, and air core coil two ends can not produce voltage, when there is AC signal in DC current, magnetic field in air core coil can change, and air core coil two ends can produce AC signal, extracts described AC signal; Because this AC signal is very faint, therefore need to be amplified described AC signal by amplifying circuit; AC signal after amplification being carried out to the filtering circuit of characteristic frequency, when there is the AC signal of described characteristic frequency in this AC signal, the AC signal of this characteristic frequency can be obtained; The method accurately can detect the AC signal of characteristic frequency in DC current, and the method cost is low, convenient and easy.
Please refer to Fig. 5, the method flow diagram of the described AC signal of extraction that Fig. 5 provides for the embodiment of the present invention; The method can comprise:
Step s200, when there is AC signal in DC current, the two ends output AC voltage signal of air core coil;
Step s200, utilize voltage integrator to process described ac voltage signal, obtain ac current signal.
Wherein, very faint owing to extracting the ac voltage signal obtained, again because voltage signal is more easily subject to extraneous interference compared to current signal, therefore in order to obtain accurate result more accurately, prevent external interference, the alternating component preferably the output AC voltage signal of extraction being synchronously reduced to corresponding primary current by voltage integrator here is also ac current signal.Please refer to Fig. 6, the voltage integrator that utilizes that Fig. 6 provides for the embodiment of the present invention processes described ac voltage signal, obtains the schematic diagram of ac current signal; Can see that the amplitude of this AC signal is larger by this figure, easier subsequent treatment.
The ac voltage signal being easily subject to external interference can be made to change more stable ac current signal into by above-mentioned process; By such conversion, subsequent treatment can be made more accurate.
Optionally, described by filtering circuit to amplify after AC signal carry out filtering process, the AC signal obtaining characteristic frequency comprises:
Utilize the high-pass filtering circuit of 0Hz ~ 49.5Hz to carry out filtering to the AC signal after described amplification, obtain the AC signal of more than 49.5Hz;
Utilize the low-pass filter circuit being greater than 50.5Hz to carry out filtering to the AC signal of described more than 49.5Hz, obtain the AC signal of 49.5Hz ~ 50.5Hz.
Wherein, if when be the AC signal of characteristic frequency being here the AC signal of 50Hz, bandwidth-limited circuit can be utilized, or the filtering circuit of low pass and high pass combination, filtering is carried out to unwanted frequency in the AC signal obtained, if when there is required frequency in this AC signal, extracted.Preferably, here use the high-pass filtering circuit of 0Hz ~ 49.5Hz that all AC signal lower than 49.5HZ collected are carried out filtering, circuit exports 49, more than 5HZ voltage signals and all AC signal higher than 50.5HZ collected are carried out filtering to the AC signal obtained by the low-pass filter circuit that is greater than 50.5Hz.After filtering after circuit, the AC signal of 49.5Hz ~ 50.5Hz can be obtained, have more 0.5Hz up and down in the AC signal of 50Hz like this and can ensure that the AC signal of whole 50Hz can obtain.
Optionally, also comprise after obtaining the AC signal of characteristic frequency described in:
The AC signal of described characteristic frequency is converted to by translation circuit the direct current signal that truck-mounted computer can identify;
Wherein, truck-mounted computer due to current electric locomotive can't be identified by the AC signal of the characteristic frequency of filtering circuit or acquisition, therefore needs the AC signal of described characteristic frequency to be converted to by translation circuit the direct current signal that truck-mounted computer can identify.
Truck-mounted computer is monitored described direct current signal, and when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
Wherein, the direct current signal after truck-mounted computer Collect conversion, and described direct current signal is monitored, when the direct current signal monitored reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.Such as disconnect direct current quick breaker etc.To ensure the security of operation of electric locomotive.The AC signal of different characteristic frequency is to there being different predetermined conditions, and when reaching predetermined condition when the AC signal of characteristic frequency, vehicle computing chance controls according to the control program under each characteristic frequency the operation that adaptation made by corresponding device.
By utilizing the AC signal of the characteristic frequency accurately detected, its precision is transformed to and by the situation of truck-mounted computer identification, can be monitored by truck-mounted computer so again, and it is then more accurate to carry out corresponding process according to monitoring result, and cost is low, effective.
Preferably, describedly the AC signal of described characteristic frequency be converted to by translation circuit the direct current signal that truck-mounted computer can identify comprise:
The AC signal of described characteristic frequency is converted to direct current signal by full-bridge rectification translation circuit;
Described direct current signal is transformed to through dc chopper DC/DC the DC current signal that truck-mounted computer can identify.
Wherein, such as, when characteristic frequency is the AC signal of 49.5HZ ~ 50.5HZ, the AC signal of 49.5HZ ~ 50.5HZ can be transformed to 0V ~ 10V direct current signal through full-bridge rectification, and it can be that other can for 4mA ~ 20mA current signal that direct-flow signal voltage signal is converted to truck-mounted computer through DC/DC conversion.
Optionally, when the characteristic frequency detected is the AC signal of 49.5Hz ~ 50.5Hz, described truck-mounted computer performs corresponding operation by preset program and comprises:
If described direct current signal reaches predetermined condition, truck-mounted computer will control direct current quick breaker and disconnect.
Wherein, the current signal being transformed to 1 ~ 60A that circuit locomotive vehicle-mounted computer acquisition system can be corresponding by transformation for mula by the 4 ~ 20mA current signal gathered.Can as described in Figure 7, the transition diagram of the truck-mounted computer that Fig. 7 provides for the embodiment of the present invention, in 4 ~ 20mA current signal, each numerical value is corresponding with the current signal of 1 ~ 60A.
Occur reaching predetermined condition when truck-mounted computer monitors in the current signal of 1 ~ 60A corresponding to 49.5HZ ~ 50.5HZ AC signal; wherein; this predetermined condition can for current value be greater than 6A and this duration being greater than the current signal of 6A more than 2S; control direct current quick breaker disconnects by truck-mounted computer, to protect cab signal system not by 50HZ current interference.
Based on technique scheme, the method of the detection characteristic frequency AC signal that the embodiment of the present invention provides, through the filtering of air core coil to direct current carrier, when there is not AC signal in DC current, the magnetic field in air core coil can not change, and air core coil two ends can not produce voltage, when there is AC signal in DC current, magnetic field in air core coil can change, and air core coil two ends can produce AC signal, extracts described AC signal; Because this AC signal is very faint, therefore need to be amplified described AC signal by amplifying circuit; AC signal after amplification being carried out to the filtering circuit of characteristic frequency, when there is the AC signal of described characteristic frequency in this AC signal, the AC signal of this characteristic frequency can be obtained; The method accurately can detect the AC signal of characteristic frequency in DC current, and the method cost is low, convenient and easy.By monitoring the AC signal of the characteristic frequency accurately extracted, can prevent the AC signal of characteristic frequency from impacting electric locomotive.And the AC signal of the characteristic frequency of acquisition can be made the accuracy of identification of truck-mounted computer is met by change-over circuit, ensure the order of accuarcy of subsequent treatment, also reducing cost does not need at the high-precision processor of use.
Embodiments provide the method detecting characteristic frequency AC signal, the AC signal of characteristic frequency in amplitude DC current accurately can be detected by said method.
Be introduced the system of the detection characteristic frequency AC signal that the embodiment of the present invention provides below, the system of detection characteristic frequency AC signal described below can mutual corresponding reference with the method for above-described detection characteristic frequency AC signal.
Please refer to Fig. 8, the structured flowchart of the system of the detection characteristic frequency AC signal that Fig. 8 provides for the embodiment of the present invention; This system can comprise:
Air core coil 100, for carrying out filtering to the DC current of powering in electric locomotive, makes, when there is AC signal in DC current, to extract described AC signal;
Amplifying circuit 200, for amplifying described AC signal;
Wherein, amplifying circuit 200 here can utilize sample resistance to carry out, and namely current signal is enlarged into through sample resistance the AC signal that computing machine can identify.
Filtering circuit 300, carries out filtering process to the AC signal after amplifying, obtains the AC signal of characteristic frequency.
Wherein, for the AC signal of the characteristic frequency of 50HZ, can obtain with filtering circuit 300 49.5HZ ~ 50.5HZ AC signal to draw together the characteristic frequency of all 50HZ AC signal with letter.The filtering circuit 300 of this 49.5HZ ~ 50.5HZ AC signal can as shown in Figure 9, the filtering circuit schematic diagram of acquisition 49.5HZ ~ 50.5HZ AC signal that Fig. 9 provides for the embodiment of the present invention;
Optionally, the system of the detection characteristic frequency AC signal that the embodiment of the present invention provides can also comprise voltage integrator, please refer to Figure 10, the structural representation of the voltage integrator that Figure 10 provides for the embodiment of the present invention;
Voltage integrator, processes for the ac voltage signal extracted air core coil, obtains ac current signal.
Optionally, the system of detection characteristic frequency AC signal that the embodiment of the present invention provides can also comprise:
Change-over circuit, for being converted to the direct current signal that truck-mounted computer can identify by the AC signal of characteristic frequency;
Truck-mounted computer, for monitoring described direct current signal, when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
Optionally, described change-over circuit comprises: dc chopper DC/DC, for direct current signal being transformed to the DC current signal that truck-mounted computer can identify.
Wherein, 49.5HZ ~ 50.5HZ AC signal that can provide for the embodiment of the present invention with reference to Figure 11, Figure 11 arrives the circuit diagram of truck-mounted computer by change-over circuit; By 49.5HZ ~ 50.5HZ AC signal by process shown in this figure, can identify by truck-mounted computer, and can gather it and monitor; And operated accordingly by the corresponding electric locomotive topworks of output control of monitoring, to protect electric locomotive security of operation.
Embodiments provide the system detecting characteristic frequency AC signal, the AC signal of characteristic frequency in amplitude DC current accurately can be detected by said system.
In instructions, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar portion mutually see.For device disclosed in embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part illustrates see method part.
Professional can also recognize further, in conjunction with unit and the algorithm steps of each example of embodiment disclosed herein description, can realize with electronic hardware, computer software or the combination of the two, in order to the interchangeability of hardware and software is clearly described, generally describe composition and the step of each example in the above description according to function.These functions perform with hardware or software mode actually, depend on application-specific and the design constraint of technical scheme.Professional and technical personnel can use distinct methods to realize described function to each specifically should being used for, but this realization should not thought and exceeds scope of the present invention.
The software module that the method described in conjunction with embodiment disclosed herein or the step of algorithm can directly use hardware, processor to perform, or the combination of the two is implemented.Software module can be placed in the storage medium of other form any known in random access memory (RAM), internal memory, ROM (read-only memory) (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.
Above the method and system of detection characteristic frequency AC signal provided by the present invention are described in detail.Apply specific case herein to set forth principle of the present invention and embodiment, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping.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 carry out some improvement and modification to the present invention, these improve and modify and also fall in the protection domain of the claims in the present invention.
Claims (10)
1. detect a method for characteristic frequency AC signal, it is characterized in that, comprising:
By air core coil, filtering is carried out to the DC current of powering in electric locomotive, extract the AC signal in described DC current;
By ac amplifier circuit, described AC signal is amplified;
By filtering circuit, filtering process is carried out to the AC signal after amplification, obtain the AC signal of characteristic frequency.
2. the method for claim 1, is characterized in that, the described AC signal of described extraction comprises:
When there is AC signal in DC current, the two ends output AC voltage signal of air core coil;
Utilize voltage integrator to process described ac voltage signal, obtain ac current signal.
3. the method for claim 1, is characterized in that, described by filtering circuit to amplify after AC signal carry out filtering process, the AC signal obtaining characteristic frequency comprises:
Utilize the high-pass filtering circuit of 0Hz ~ 49.5Hz to carry out filtering to the AC signal after described amplification, obtain the AC signal of more than 49.5Hz;
Utilize the low-pass filter circuit being greater than 50.5Hz to carry out filtering to the AC signal of described more than 49.5Hz, obtain the AC signal of 49.5Hz ~ 50.5Hz.
4. the method for claim 1, is characterized in that, described in obtain the AC signal of characteristic frequency after also comprise:
The AC signal of described characteristic frequency is converted to by translation circuit the direct current signal that truck-mounted computer can identify;
Truck-mounted computer is monitored described direct current signal, and when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
5. method as claimed in claim 4, is characterized in that, describedly the AC signal of described characteristic frequency is converted to by translation circuit the direct current signal that truck-mounted computer can identify comprises:
The AC signal of described characteristic frequency is converted to direct current signal by full-bridge rectification translation circuit;
Described direct current signal is transformed to through dc chopper DC/DC the DC current signal that truck-mounted computer can identify.
6. method as claimed in claim 4, is characterized in that, when the characteristic frequency detected is the AC signal of 49.5Hz ~ 50.5Hz, described truck-mounted computer performs corresponding operation by preset program and comprises:
If described direct current signal reaches predetermined condition, truck-mounted computer will control direct current quick breaker and disconnect.
7. detect a system for characteristic frequency AC signal, it is characterized in that, comprising:
Air core coil, for carrying out filtering to the DC current of powering in electric locomotive, makes, when there is AC signal in DC current, to extract described AC signal;
Amplifying circuit, for amplifying described AC signal;
Filtering circuit, carries out filtering process to the AC signal after amplifying, obtains the AC signal of characteristic frequency.
8. system as claimed in claim 7, is characterized in that, also comprise:
Change-over circuit, for being converted to the direct current signal that truck-mounted computer can identify by the AC signal of characteristic frequency;
Truck-mounted computer, for monitoring described direct current signal, when described direct current signal reaches predetermined condition, truck-mounted computer performs corresponding operation by preset program.
9. system as claimed in claim 8, it is characterized in that, described change-over circuit comprises: dc chopper DC/DC, for direct current signal being transformed to the DC current signal that truck-mounted computer can identify.
10. system as claimed in claim 7, is characterized in that, also comprise: voltage integrator, process, obtain ac current signal for the ac voltage signal extracted air core coil.
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Application publication date: 20150325 |