CN111965422A - Frequency monitoring circuit - Google Patents
Frequency monitoring circuit Download PDFInfo
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- CN111965422A CN111965422A CN202010708249.3A CN202010708249A CN111965422A CN 111965422 A CN111965422 A CN 111965422A CN 202010708249 A CN202010708249 A CN 202010708249A CN 111965422 A CN111965422 A CN 111965422A
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 6
- 238000013461 design Methods 0.000 abstract description 3
- 239000003990 capacitor Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
- G01R23/06—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into an amplitude of current or voltage
Abstract
The invention discloses a frequency monitoring circuit, which comprises an RC filter circuit, a reference voltage circuit, two comparison circuits and a switch circuit, wherein the RC filter circuit is connected with the reference voltage circuit; wherein: the RC filter circuit processes the frequency signal to be monitored into a direct-current voltage signal; the reference voltage circuit generates two paths of reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold; the two comparison circuits respectively realize the comparison between the direct-current voltage signals generated by the RC filter circuit and the reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold, and output signals of the comparison circuits are connected to the switch circuit; and the switching circuit outputs a fault signal when the frequency of the frequency signal exceeds a set threshold range. The invention adopts different reference voltages corresponding to different frequency thresholds, can flexibly adjust the monitoring range of the frequency by adjusting the value of the reference voltage, and reduces the circuit cost. Meanwhile, the frequency signals are filtered into voltage signals for comparison, so that the circuit design is simplified, and the circuit reliability is improved.
Description
Technical Field
The present invention relates to frequency signal monitoring, and more particularly to a frequency monitoring circuit.
Background
With the technical development of high-tech fields such as communication synchronization, test metering and the like, the demand of frequency signals is increased, and more occasions are needed for monitoring the frequency signals. In the motor controller, if the clock frequency signal of the MCU chip fails, a control instruction may not be sent normally, and the motor will operate according to an expected condition, so that the clock frequency signal of the MCU chip is monitored to further execute a corresponding control strategy in order to avoid risks caused by unexpected operation, and the safety and reliability of the system can be greatly improved.
This patent has designed a frequency monitoring circuit based on the demand of the security and the reliability of system.
The closest technology to the technology is mainly as follows:
1. monitoring the phase difference between the frequency to be monitored and the reference frequency, and obtaining corresponding frequency deviation through an evaluating circuit so as to realize the monitoring of the frequency signal; according to the scheme, the frequency monitoring is realized by carrying out phase comparison on the frequency to be monitored and the reference frequency, a reference frequency generating circuit needs to be added, and the cost of the circuit is increased.
2. Capturing the rising edge of a frequency signal to be detected through a signal processing chip, and obtaining the frequency of the signal through calculation so as to realize frequency monitoring; according to the scheme, the signal processing chip captures the rising edge of the frequency signal to be detected, so that frequency monitoring is realized, and when the clock frequency signal of the signal processing chip is in fault, fault detection cannot be realized.
Disclosure of Invention
The invention aims to: based on the requirements of safety and reliability of the system, the invention designs a frequency monitoring circuit.
The technical scheme of the invention is as follows:
a frequency monitoring circuit comprises an RC filter circuit, a reference voltage circuit, two comparison circuits and a switch circuit; wherein:
the RC filter circuit processes the frequency signal to be monitored into a direct-current voltage signal;
the reference voltage circuit generates two paths of reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold;
the two comparison circuits respectively realize the comparison between the direct-current voltage signals generated by the RC filter circuit and the reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold, and output signals of the comparison circuits are connected to the switch circuit;
and the switching circuit outputs a fault signal when the frequency of the frequency signal exceeds a set threshold range.
Preferably, the frequency monitoring threshold is adjusted by adjusting two paths of reference voltages corresponding to the upper and lower limit frequency thresholds generated by the reference voltage circuit.
Preferably, the reference voltage adjusting circuit is composed of a plurality of voltage dividing resistors, and the reference voltages corresponding to the upper and lower threshold values are obtained through resistor voltage division and are respectively input to the non-inverting terminals of the first and second comparison circuits,
and respectively inputting the frequency signals filtered by the RC filter circuit to the inverting ends of the first comparison circuit and the second comparison circuit.
In another scheme, the reference voltage circuit is composed of a low dropout linear regulator.
Preferably, the switching circuit comprises two first switching units and two second switching units, wherein the first switching units and the second switching units are respectively composed of switching tubes; the output ends of the two switch units are connected together and used as the output end of the switch circuit.
Preferably, the switching tube in the switching circuit is a transistor or a MOS tube.
Preferably, when the frequency signal exceeds the upper limit frequency threshold, the first comparison circuit outputs a low level signal to control the first switch unit to be switched on, and the switch circuit outputs a high level fault signal;
when the frequency signal is lower than the lower limit frequency threshold, the second comparison circuit outputs a high level signal to control the second switch unit to be conducted, and the switch circuit outputs a high level fault signal;
when the frequency signal is in the set frequency range, the first comparison circuit outputs a high level, the second comparison circuit outputs a low level, the two switch units are not conducted, and the switch circuit outputs a low level signal.
In another scheme, when the frequency signal exceeds an upper limit frequency threshold, the first comparison circuit outputs a low level signal to control the first switch unit to be switched on, and the switch circuit outputs a low level fault signal;
when the frequency signal is lower than the lower limit frequency threshold, the second comparison circuit outputs a high level signal to control the second switch unit to be conducted, and the switch circuit outputs a low level fault signal;
when the frequency signal is in the set frequency range, the first comparison circuit outputs a high level, the second comparison circuit outputs a low level, the two switch units are not conducted, and the switch circuit outputs a high level signal.
The invention has the advantages that:
1. the invention adopts different reference voltages corresponding to different frequency thresholds, and can flexibly adjust the monitoring range of the frequency by adjusting the value of the reference voltage.
2. The frequency signal to be monitored is filtered into a direct-current voltage signal, and the direct-current voltage signal is compared with the reference voltage corresponding to the upper limit frequency threshold and the lower limit frequency threshold respectively, so that the signal frequency is monitored. The reference frequency generation circuit required by the scheme of directly comparing the reference frequency with the reference frequency is solved, and the circuit cost is reduced. Meanwhile, the frequency signals are filtered into voltage signals for comparison, so that the circuit design is simplified, and the circuit reliability is improved.
Drawings
The invention is further described with reference to the following figures and examples:
FIG. 1 is a schematic diagram of a frequency monitoring circuit according to the present invention;
fig. 2 is a schematic diagram of an embodiment of the frequency monitoring circuit of the present invention.
Detailed Description
As shown in fig. 1, the frequency monitoring circuit of the present invention includes an RC filter circuit, a reference voltage circuit, two comparison circuits, and a switch circuit; wherein:
the RC filter circuit processes the frequency signal to be monitored into a direct-current voltage signal;
the reference voltage circuit generates two paths of reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold;
the two comparison circuits respectively realize the comparison between the direct-current voltage signals generated by the RC filter circuit and the reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold, and output signals of the comparison circuits are connected to the switch circuit;
and the switching circuit outputs a fault signal when the frequency of the frequency signal exceeds a set threshold range.
As shown in fig. 2, the RC filter circuit is composed of capacitors C1 and C2, resistors R1 and R2, and voltage regulators D1 and D2, and processes frequency signals to be monitored into direct-current voltage signals.
The reference voltage adjusting circuit is composed of three voltage dividing resistors R3, R4 and R5 which are connected in series, a reference voltage corresponding to an upper limit threshold value is output through a capacitor C3 and a resistor R6, and a reference voltage corresponding to a lower limit threshold value is output through a capacitor C4 and a resistor R7. And the reference voltages corresponding to the upper and lower limit thresholds are respectively input to the in-phase ends of the first and second comparison circuits, and the frequency signals filtered by the RC filter circuit are respectively input to the inverting ends of the first and second comparison circuits.
The reference voltage circuit can also be composed of a low dropout linear regulator, i.e. an LDO circuit.
The frequency monitoring threshold value can be adjusted by adjusting the two paths of reference voltages corresponding to the upper and lower limit frequency threshold values generated by the reference voltage circuit.
In fig. 2, the switching circuit includes two first switching units and two second switching units, each of which is composed of a transistor Q1B and a transistor Q2A; the output ends of the two switch units are connected together and used as the output end of the switch circuit.
Besides the transistor, the switch tube in the switch circuit can also adopt an MOS tube.
The embodiment specifically works as follows:
when the frequency signal exceeds the upper limit frequency threshold, the first comparison circuit outputs a low level signal to control the first switch unit to be conducted, and the switch circuit outputs a high level fault signal;
when the frequency signal is lower than the lower limit frequency threshold, the second comparison circuit outputs a high level signal to control the second switch unit to be conducted, and the switch circuit outputs a high level fault signal;
when the frequency signal is in the set frequency range, the first comparison circuit outputs a high level, the second comparison circuit outputs a low level, the two switch units are not conducted, and the switch circuit outputs a low level signal.
When the invention is implemented, the switching circuit can output low level as fault signal by changing the connection method of the switching tube.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All modifications made according to the spirit of the main technical scheme of the invention are covered in the protection scope of the invention.
Claims (8)
1. A frequency monitoring circuit is characterized by comprising an RC filter circuit, a reference voltage circuit, two comparison circuits and a switch circuit; wherein:
the RC filter circuit processes the frequency signal to be monitored into a direct-current voltage signal;
the reference voltage circuit generates two paths of reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold;
the two comparison circuits respectively realize the comparison between the direct-current voltage signals generated by the RC filter circuit and the reference voltages corresponding to the upper limit frequency threshold and the lower limit frequency threshold, and output signals of the comparison circuits are connected to the switch circuit;
and the switching circuit outputs a fault signal when the frequency of the frequency signal exceeds a set threshold range.
2. The frequency monitoring circuit according to claim 1, wherein the adjustment of the frequency monitoring threshold is achieved by adjusting two reference voltages corresponding to the upper and lower frequency thresholds generated by the reference voltage circuit.
3. The frequency monitoring circuit of claim 1,
the reference voltage adjusting circuit consists of a plurality of divider resistors, reference voltages corresponding to upper and lower limit thresholds are obtained through resistor voltage division and are respectively input to the in-phase ends of the first comparison circuit and the second comparison circuit;
and respectively inputting the frequency signals filtered by the RC filter circuit to the inverting ends of the first comparison circuit and the second comparison circuit.
4. The frequency monitoring circuit of claim 3,
the switching circuit comprises a first switching unit and a second switching unit, wherein the first switching unit and the second switching unit are respectively composed of switching tubes; the output ends of the two switch units are connected together and used as the output end of the switch circuit.
5. The frequency monitoring circuit of claim 4,
when the frequency signal exceeds the upper limit frequency threshold, the first comparison circuit outputs a low level signal to control the first switch unit to be conducted, and the switch circuit outputs a high level fault signal;
when the frequency signal is lower than the lower limit frequency threshold, the second comparison circuit outputs a high level signal to control the second switch unit to be conducted, and the switch circuit outputs a high level fault signal;
when the frequency signal is in the set frequency range, the first comparison circuit outputs a high level, the second comparison circuit outputs a low level, the two switch units are not conducted, and the switch circuit outputs a low level signal.
6. The frequency monitoring circuit of claim 1,
the reference voltage circuit is composed of a low dropout linear regulator.
7. The frequency monitoring circuit of claim 4,
and a switching tube in the switching circuit adopts a transistor or an MOS tube.
8. The frequency monitoring circuit of claim 4,
when the frequency signal exceeds the upper limit frequency threshold, the first comparison circuit outputs a low level signal to control the first switch unit to be conducted, and the switch circuit outputs a low level fault signal;
when the frequency signal is lower than the lower limit frequency threshold, the second comparison circuit outputs a high level signal to control the second switch unit to be conducted, and the switch circuit outputs a low level fault signal;
when the frequency signal is in the set frequency range, the first comparison circuit outputs a high level, the second comparison circuit outputs a low level, the two switch units are not conducted, and the switch circuit outputs a high level signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010708249.3A CN111965422A (en) | 2020-07-22 | 2020-07-22 | Frequency monitoring circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010708249.3A CN111965422A (en) | 2020-07-22 | 2020-07-22 | Frequency monitoring circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111965422A true CN111965422A (en) | 2020-11-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010708249.3A Pending CN111965422A (en) | 2020-07-22 | 2020-07-22 | Frequency monitoring circuit |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103022965A (en) * | 2012-12-20 | 2013-04-03 | 安徽巨一自动化装备有限公司 | Monitoring circuit of 12V voltage in electric vehicle electric drive controller |
| CN103077346A (en) * | 2012-12-20 | 2013-05-01 | 深圳国微技术有限公司 | Clock frequency detection based chip anti-attack system and method |
| CN103677082A (en) * | 2013-12-20 | 2014-03-26 | 深圳国微技术有限公司 | Clock frequency monitoring circuit and method |
| CN104218532A (en) * | 2014-09-19 | 2014-12-17 | 中冶南方（武汉）自动化有限公司 | Voltage protection circuit for frequency converter direct current (DC) bus |
| CN206099298U (en) * | 2016-10-19 | 2017-04-12 | 山东艾诺仪器有限公司 | Power supply monitoring circuit |
| CN208479166U (en) * | 2018-08-09 | 2019-02-05 | 上海奉天电子股份有限公司 | A kind of high-precision overvoltage/undervoltage detection control circuit |
-
2020
- 2020-07-22 CN CN202010708249.3A patent/CN111965422A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103022965A (en) * | 2012-12-20 | 2013-04-03 | 安徽巨一自动化装备有限公司 | Monitoring circuit of 12V voltage in electric vehicle electric drive controller |
| CN103077346A (en) * | 2012-12-20 | 2013-05-01 | 深圳国微技术有限公司 | Clock frequency detection based chip anti-attack system and method |
| CN103677082A (en) * | 2013-12-20 | 2014-03-26 | 深圳国微技术有限公司 | Clock frequency monitoring circuit and method |
| CN104218532A (en) * | 2014-09-19 | 2014-12-17 | 中冶南方（武汉）自动化有限公司 | Voltage protection circuit for frequency converter direct current (DC) bus |
| CN206099298U (en) * | 2016-10-19 | 2017-04-12 | 山东艾诺仪器有限公司 | Power supply monitoring circuit |
| CN208479166U (en) * | 2018-08-09 | 2019-02-05 | 上海奉天电子股份有限公司 | A kind of high-precision overvoltage/undervoltage detection control circuit |
Non-Patent Citations (1)
| Title |
|---|
| 王宏，张江石: "《安全仪器监测工：从入门到精通》", 煤炭工业出版社, pages: 29 * |
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Application publication date: 20201120 |
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