CN112491001B - Filtering-free signal acquisition method and system and leakage protection device - Google Patents
Filtering-free signal acquisition method and system and leakage protection device Download PDFInfo
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- CN112491001B CN112491001B CN202011405891.0A CN202011405891A CN112491001B CN 112491001 B CN112491001 B CN 112491001B CN 202011405891 A CN202011405891 A CN 202011405891A CN 112491001 B CN112491001 B CN 112491001B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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Abstract
The invention discloses a filtering-free signal acquisition method, which relates to the technical field of signal acquisition methods and comprises the following steps: step S1: generating a PWM carrier signal with a certain frequency F through a main control end and outputting the PWM carrier signal to a modulation signal end; step S2: the modulation signal end modulates information to be detected onto a PWM carrier signal to form a modulation signal with a carrier, and the modulation signal is transmitted to the main control end; step S3: the main control end obtains N according to a modulation signal oscillogram with a carrier; step S4: calculating the delay time T according to a formula T = (1/F) × N; step S5: and the main control end carries out ADC sampling on the modulation signal with the carrier wave at the optimal sampling time point M in each PWM carrier wave signal period to obtain information to be detected. The invention collects the modulation signal with the carrier wave at the best sampling time without filtering the signal, thereby increasing the reliability of the product and effectively reducing the volume of the product.
Description
Technical Field
The invention relates to the technical field of signal acquisition methods, in particular to a filtering-free signal acquisition method, a system thereof and a leakage protection device.
Background
In recent years, signal acquisition technologies are widely applied in more and more fields, and in the traditional signal acquisition technologies, before data sampling, a peripheral hardware filter circuit is firstly built to filter carrier signals, only baseband signals are left, and then the baseband signals are sampled. The peripheral hardware filter circuit is built, so that the reliability of the product is reduced, the hardware cost is increased, and the miniaturization degree of the product is limited.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a filtering-free signal acquisition method, a system thereof and a leakage protection device.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a filtering-free signal acquisition method comprises the following steps:
step S1: generating a PWM carrier signal with a certain frequency F through a main control end, and outputting the PWM carrier signal to a modulation signal end;
step S2: after receiving a PWM carrier signal with the frequency of F, the modulation signal end modulates information to be detected onto the PWM carrier signal to form a modulation signal with a carrier, and retransmits the modulation signal to the main control end;
step S3: the main control end receives a modulation signal with a carrier, and obtains N according to a waveform diagram of the modulation signal with the carrier, wherein N is the proportion of the time interval between the time point with the minimum waveform slope close to the waveform starting point and the waveform starting point in each waveform period to the whole waveform period;
step S4: calculating delay time T according to a formula T = (1/F) × N, wherein T is a time interval from the starting point of each waveform period to an optimal sampling time point M;
step S5: and the main control end carries out ADC sampling on the modulation signal with the carrier wave at the optimal sampling time point M in each PWM carrier wave signal period to obtain information to be detected.
As a preferable scheme of the filtering-free signal acquisition method of the present invention, wherein: the information to be detected may be leakage information.
The invention also discloses a filtering-free signal acquisition system, which comprises: the main control module is used for generating a PWM carrier signal with a certain frequency F, outputting the PWM carrier signal to a modulation signal end, obtaining N according to a waveform diagram of the modulation signal with the carrier after receiving the modulation signal with the carrier returned by the signal modulation module, wherein N is the proportion of the time interval between the time point with the minimum waveform slope close to the waveform starting point and the waveform starting point in each waveform period to the whole waveform period, calculating the delay time T according to a formula T = (1/F) × N, and performing ADC sampling on the modulation signal with the carrier after the delay time T passes through the starting point of each PWM carrier signal period to obtain information to be detected; and the signal modulation module is used for modulating the information to be detected onto the PWM carrier signal after receiving the PWM carrier signal with the frequency F generated by the main control module to form a modulation signal with carrier and retransmitting the modulation signal to the main control module.
As a preferable scheme of the filtering-free signal acquisition system of the present invention, wherein: the master control module comprises an MCU master control chip with the model of XMC1302 or a master control chip with the model of STM32G 071.
As a preferable scheme of the filtering-free signal acquisition system of the present invention, wherein: the signal modulation module comprises a magnetic core winding and a signal source to be tested, the magnetic core winding comprises a magnetic core, and an N1 winding and an N2 winding which are wound on the magnetic core, the main control module is connected with the N1 winding, and the signal source to be tested is connected with the N2 winding.
The invention also discloses a leakage protection device, which comprises an MCU circuit board, a magnetic core winding, a relay and a leakage signal source, wherein the MCU circuit board, the magnetic core winding, the relay and the leakage signal source are arranged in a shell, the relay is connected with the MCU circuit board, the magnetic core winding comprises a magnetic core, an N1 winding and an N2 winding, the N1 winding and the N2 winding are wound on the magnetic core, the MCU circuit board is connected with the N1 winding, the leakage signal source is connected with the N2 winding, the MCU circuit board generates a PWM carrier signal, leakage information is modulated onto the PWM carrier signal through the magnetic core winding to form a modulation signal with carrier waves, and the modulation signal with carrier waves is transmitted back to the MCU circuit board, an MCU main control chip on the MCU circuit board directly acquires the leakage information without filtering the modulation signal with carrier waves, and controls the relay to act according to the leakage information, so that leakage protection is realized.
As a preferable aspect of the earth leakage protection device of the present invention, wherein: the model of the MCU master control chip is XMC1302 or STM32G 071.
The invention has the beneficial effects that:
(1) when the periodic excitation signal is level, the magnetic core works in a linear region, the change of the detected signal can be effectively detected, the point with the minimum sampling waveform slope is provided, the detection precision of the magnetic core is highest, and the change of the detected signal can be reflected most, so that the modulation signal with the carrier wave is acquired at the optimal sampling time, the signal does not need to be filtered, the reliability of the product is improved, and the volume of the product is effectively reduced;
(2) the invention saves a hardware filter circuit in an external circuit, effectively reduces the number of components and saves the development and production cost of the hardware filter circuit.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a waveform diagram of a PWM carrier signal according to an embodiment;
FIG. 2 is a waveform diagram of a modulated signal with a carrier wave in an embodiment;
FIG. 3 is a schematic diagram of an optimal sampling time in a waveform diagram of a modulated signal with a carrier in an embodiment;
FIG. 4 is a schematic diagram of an embodiment of an earth leakage protection device;
FIG. 5 is a schematic diagram of a modulation signal with carrier entering a main control chip MCU in an embodiment;
fig. 6 is a diagram of sampling beats of the ADC in the embodiment.
Detailed Description
In order that the present invention may be more readily and clearly understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings.
Example 1:
the embodiment provides a filtering-free signal acquisition method, which comprises the following steps:
step S1: a PWM carrier signal with a frequency of 6KHz is generated by the main control terminal and output to the modulation signal terminal, wherein a waveform diagram of the PWM carrier signal is shown in fig. 1.
Step S2: after receiving the PWM carrier signal with the frequency of 6KHz, the modulation signal end modulates information to be detected, such as a leakage signal, onto the PWM carrier signal to form a modulation signal with carrier, and retransmits the modulation signal to the main control end, where a waveform diagram of the modulation signal with carrier is shown in fig. 2.
Step S3: the main control end receives a modulation signal with a carrier, and obtains a machine N according to a waveform diagram of the modulation signal with the carrier, wherein N is a proportion of a time interval between a time point adjacent to a waveform starting point and having a minimum waveform slope in each waveform period and the waveform starting point in the whole waveform period, specifically, in the waveform diagram of the modulation signal with the carrier, a point which is a quarter of the waveform period away from the waveform starting point in each period is the smoothest, the slope is the minimum, and therefore N is a quarter, as shown by a dotted line in fig. 3.
Step S4: the delay time T, which is the time interval between the starting point of each waveform cycle and the optimal sampling timing point M, is calculated according to the formula T = (1/F) × N, i.e., T = 1000000/(6000 × 4) = 41.67 us.
Step S5: and the main control end carries out ADC sampling on the modulation signal with the carrier wave at the optimal sampling time point M in each PWM carrier wave signal period to obtain information to be detected.
When the periodic excitation signal is level and gentle, the magnetic core works in a linear region, the change of the detected signal can be effectively detected, the point with the minimum sampling waveform slope is provided, the detection precision of the magnetic core is highest, and the change of the detected signal can be reflected most, so that the modulation signal with the carrier wave is acquired through the optimal sampling time point M, the signal does not need to be filtered, the reliability of a product is improved, the volume of the product is effectively reduced, meanwhile, a hardware filter circuit in an external circuit is omitted, the number of components is effectively reduced, and the development and production cost of the hardware filter circuit is saved.
Corresponding to the filtering-free signal acquisition method, the embodiment further provides a filtering-free signal acquisition system, which comprises a main control module and a signal modulation module. The main control module is used for generating a PWM carrier signal with a certain frequency F and outputting the PWM carrier signal to the modulation signal end. And the signal modulation module is used for modulating the information to be detected onto the PWM carrier signal after receiving the PWM carrier signal with the frequency F generated by the main control module to form a modulation signal with carrier and retransmitting the modulation signal to the main control module. The main control module obtains N according to a waveform diagram of the modulation signal with the carrier after receiving the modulation signal with the carrier returned by the signal modulation module, wherein N is a proportion of a time interval between a time point with the minimum waveform slope close to a waveform starting point and the waveform starting point in each waveform period to the whole waveform period, calculates a delay time T according to a formula T = (1/F) × N, and performs ADC sampling on the modulation signal with the carrier after the delay time T passes through the starting point of each PWM carrier signal period to obtain information to be detected.
The main control module comprises an MCU main control chip with the model of XMC1302 or the model of STM32G 071. The signal modulation module comprises a magnetic core winding and a signal source to be measured, the magnetic core winding comprises a magnetic core, an N1 winding and an N2 winding, the N1 winding and the N2 winding are wound on the magnetic core, the MCU main control chip is connected with the N1 winding, the signal source to be measured is connected with the N2 winding, signals output by the N1 winding of the magnetic core winding comprise signals to be measured and PWM carrier signals according to the fluxgate principle, and reference voltage Vref is modulated on the signals to form modulation signals with carriers.
Example 2:
the embodiment provides a leakage protection device, which comprises an MCU circuit board, a magnetic core winding, a relay and a leakage signal source, wherein the MCU circuit board, the magnetic core winding, the relay and the leakage signal source are arranged in a shell. The relay is connected with the MCU circuit board. The magnetic core winding comprises a magnetic core, an N1 winding and an N2 winding, the N1 winding and the N2 winding are wound on the magnetic core, the MCU circuit board is connected with the N1 winding, and the leakage signal source is connected with the N2 winding. The MCU circuit board generates a PWM carrier signal and transmits the PWM carrier signal to the magnetic core winding, according to the fluxgate principle, a signal output by the N1 winding in the magnetic core winding comprises a signal to be acquired and the PWM carrier signal, a reference voltage Vref is modulated on the signal to form a modulation signal with a carrier and is transmitted back to the MCU circuit board, an MCU main control chip on the MCU circuit board directly acquires leakage information on the modulation signal with the carrier without filtering, and the relay is controlled to act according to the leakage information to realize leakage protection.
It should be noted that the MCU main control chip needs to have more than two ADC conversion modules, more than one PWM wave generation module with a frequency of about 6KHz, more than one serial port module, and several GPIO ports, so the model of the MCU main control chip is XMC1302 or STM32G071, and of course, other main control chips meeting the requirements can also be used.
The leakage protection device is free of a hardware filter circuit, the modulation signal with the carrier comprises a PWM carrier signal when entering the main control chip MCU, fig. 5 shows the modulation signal with the carrier entering the main control chip MCU, the leakage signal is an alternating current leakage signal with 50Hz, and as can be seen from fig. 5, the sampling signal comprises the PWM carrier signal with the frequency of 6KHz, and the leakage signal can be obtained by directly sampling without filtering through the constraint on the sampling time.
Fig. 6 is an ADC sampling beat graph, in which a solid line waveform is a modulation signal with a 6KHz PWM carrier signal returned to the main control chip MCU, and a dotted line waveform is a sampling beat performed by using the ADC data sampling module of the main control chip MCU after the sampling timing is constrained by the method of the present invention, and the acquired data is leakage signal data.
In addition to the above embodiments, the present invention may have other embodiments; all technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (5)
1. A filtering-free signal acquisition method is characterized in that: the method comprises the following steps:
step S1: generating a PWM carrier signal with a certain frequency F through a main control end, and outputting the PWM carrier signal to a modulation signal end;
step S2: after receiving a PWM carrier signal with the frequency of F, the modulation signal end modulates information to be detected onto the PWM carrier signal to form a modulation signal with a carrier, and retransmits the modulation signal to the main control end;
step S3: the main control end receives a modulation signal with a carrier, and obtains N according to a waveform diagram of the modulation signal with the carrier, wherein N is the proportion of the time interval between the time point with the minimum waveform slope close to the waveform starting point and the waveform starting point in each waveform period to the whole waveform period;
step S4: calculating delay time T according to a formula T = (1/F) × N, wherein T is a time interval from a starting point of each waveform period to an optimal sampling time point M;
step S5: and the main control end carries out ADC sampling on the modulation signal with the carrier wave at the optimal sampling time point M in each PWM carrier wave signal period to obtain information to be detected.
2. The filter-free signal acquisition method according to claim 1, wherein: the information to be detected is leakage information.
3. A filtering-free signal acquisition system is characterized in that: the method comprises the following steps:
the main control module is used for generating a PWM carrier signal with a certain frequency F, outputting the PWM carrier signal to a modulation signal end, obtaining N according to a waveform diagram of the modulation signal with the carrier after receiving the modulation signal with the carrier returned by the signal modulation module, wherein N is the proportion of the time interval between the time point with the minimum waveform slope close to the waveform starting point and the waveform starting point in each waveform period to the whole waveform period, calculating the delay time T according to a formula T = (1/F) × N, and performing ADC sampling on the modulation signal with the carrier after the delay time T passes through the starting point of each PWM carrier signal period to obtain information to be detected;
and the signal modulation module is used for modulating the information to be detected onto the PWM carrier signal after receiving the PWM carrier signal with the frequency F generated by the main control module to form a modulation signal with carrier and retransmitting the modulation signal to the main control module.
4. The filter-free signal acquisition system of claim 3, wherein: the master control module comprises an MCU master control chip with the model of XMC1302 or a master control chip with the model of STM32G 071.
5. The filter-free signal acquisition system of claim 3, wherein: the signal modulation module comprises a magnetic core winding and a signal source to be tested, the magnetic core winding comprises a magnetic core, and an N1 winding and an N2 winding which are wound on the magnetic core, the main control module is connected with the N1 winding, and the signal source to be tested is connected with the N2 winding.
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| CN113495186B (en) * | 2021-07-27 | 2024-03-15 | 国创移动能源创新中心(江苏)有限公司 | Signal acquisition method, device and protection system of magnetic modulation current transformer |
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| CN101325404A (en) * | 2007-06-11 | 2008-12-17 | 震一科技股份有限公司 | Frequency-hopping carrier generator |
| CN102355283A (en) * | 2011-09-23 | 2012-02-15 | 青岛鼎信通讯有限公司 | ASIC (application-specific integrated circuit) chip applicable to low-voltage power line carrier communication |
| WO2015139655A1 (en) * | 2014-03-21 | 2015-09-24 | 上海电科电器科技有限公司 | Residual current protection device |
| CN107607779A (en) * | 2016-07-12 | 2018-01-19 | 上海盛相电子科技有限公司 | Electric current detecting method and device based on magnetic modulation technique |
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- 2020-12-04 CN CN202011405891.0A patent/CN112491001B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325404A (en) * | 2007-06-11 | 2008-12-17 | 震一科技股份有限公司 | Frequency-hopping carrier generator |
| CN102355283A (en) * | 2011-09-23 | 2012-02-15 | 青岛鼎信通讯有限公司 | ASIC (application-specific integrated circuit) chip applicable to low-voltage power line carrier communication |
| WO2015139655A1 (en) * | 2014-03-21 | 2015-09-24 | 上海电科电器科技有限公司 | Residual current protection device |
| CN107607779A (en) * | 2016-07-12 | 2018-01-19 | 上海盛相电子科技有限公司 | Electric current detecting method and device based on magnetic modulation technique |
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