CN116068244A - Wide-range overcurrent detection protection circuit, protection method and device for power meter - Google Patents
Wide-range overcurrent detection protection circuit, protection method and device for power meter Download PDFInfo
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- CN116068244A CN116068244A CN202310208363.3A CN202310208363A CN116068244A CN 116068244 A CN116068244 A CN 116068244A CN 202310208363 A CN202310208363 A CN 202310208363A CN 116068244 A CN116068244 A CN 116068244A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/36—Overload-protection arrangements or circuits for electric measuring instruments
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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Abstract
The invention belongs to the technical field of overcurrent detection protection, and particularly relates to a wide-range overcurrent detection protection circuit, a protection method and a device for a power meter, wherein the protection method comprises the following steps: the current signal sampling circuit is suitable for receiving an externally input current signal; the output end of the current signal sampling circuit is connected with the input end of the current signal filtering circuit; the output end of the current signal filtering circuit is connected with the input end of the current signal conditioning circuit; the output end of the current signal conditioning circuit is connected with the input end of the current signal comparison circuit; the output end of the current signal comparison circuit is connected with the input end of the overcurrent detection comparison output circuit; the output signal of the overcurrent detection comparison output circuit is used as an input signal for CPU overcurrent detection judgment; the multi-path sampling resistor is selected as a relay, and the rapid real-time sampling, accurate judgment and timely protection of external current signals are realized by matching an amplifying and conditioning circuit, a full-wave rectifying circuit and a two-stage comparator circuit.
Description
Technical Field
The invention belongs to the technical field of overcurrent detection protection, and particularly relates to a wide-range overcurrent detection protection circuit, a protection method and a device for a power meter.
Background
With the rapid development of the modern power electronic industry, power supply and load products are more and more, most of power electronic systems are not powered on or loaded, and the performance of related products is directly affected due to the related problems of conversion efficiency of the power supply, load power consumption and the like, so that special measuring instruments are required to detect the energy consumption use condition of the systems, and the requirements of household appliance manufacturers on detection of the power supply products and household appliances by using digital power meters are increased; however, since the current power equipment is developing in the direction of high current and high power, the digital power meter is becoming more and more popular for measuring the high current and high power equipment, and when the high current is connected into the instrument, if the instrument does not have more perfect overcurrent detection and protection functions, the instrument and operators are potentially damaged, so that an accurate and rapid overcurrent detection circuit is designed to have great protection and warning effects on the measuring instrument and operators.
Therefore, based on the above technical problems, a new protection circuit, protection method and device for detecting the wide range of overcurrent for the power meter are needed to be designed.
Disclosure of Invention
The invention aims to provide a wide-range overcurrent detection protection circuit, a protection method and a device for a power meter.
In order to solve the above technical problems, the present invention provides a wide-range overcurrent detection protection circuit for a power meter, comprising:
the current signal sampling circuit, the current signal filtering circuit, the current signal conditioning circuit, the current signal comparison circuit and the overcurrent detection comparison output circuit;
the current signal sampling circuit is suitable for receiving an externally input current signal;
the output end of the current signal sampling circuit is connected with the input end of the current signal filtering circuit;
the output end of the current signal filtering circuit is connected with the input end of the current signal conditioning circuit;
the output end of the current signal conditioning circuit is connected with the input end of the current signal comparison circuit;
the output end of the current signal comparison circuit is connected with the input end of the overcurrent detection comparison output circuit;
and the output signal of the overcurrent detection comparison output circuit is used as an input signal for CPU overcurrent detection judgment.
Further, the current signal sampling circuit is adapted to convert an externally input current signal into a voltage signal.
Further, the current signal filtering circuit performs filtering processing on the sampled voltage signal and performs primary overcurrent protection.
Further, the current signal conditioning circuit is suitable for adjusting the amplitude and the phase of the output signal of the current signal filtering circuit.
Further, the current signal comparison circuit is adapted to compare the input sampled and conditioned voltage signal with a set overcurrent reference voltage to obtain a compared overcurrent detection comparison signal, and
the current signal comparison circuit is suitable for detecting overcurrent under different measuring ranges by adopting a multi-range matching method.
Further, the over-current detection comparison output circuit is suitable for completing conversion of the level signal according to the over-current detection comparison signal, so that the level signal meets the pin level detection requirement of the CPU of the microprocessor.
In a second aspect, the present invention also provides a wide-range overcurrent detection protection method using the wide-range overcurrent detection protection circuit for a power meter, including:
converting a current signal into a voltage signal
Filtering noise signals of the voltage signals to obtain purer signals;
the method comprises the steps of adjusting amplitude and phase of a purer signal, adjusting a sine waveform with lower amplitude to a half-wave sine signal with higher amplitude, and taking the half-wave sine signal as an input comparison signal of a current signal comparison circuit;
obtaining an output comparison signal according to the input comparison signal;
and performing level signal conversion according to the output comparison signal.
Further, the method for obtaining the output comparison signal according to the input comparison signal comprises the following steps:
outputting a comparison signal Vsg5 according to comparison thresholds of the current signal two-stage comparison circuit and the first comparator;
the comparison signal Vsg6 is output according to the comparison threshold values of the current signal two-stage comparison circuit and the second comparator.
Further, the level signal is converted to output a signal Vsg7;
the Vsg7 is output to an external microprocessor CPU for detection processing to determine whether an external current is flowing.
In a third aspect, the present invention also provides a broad-range overcurrent detection protection device, including:
the wide-range overcurrent detection protection circuit for the power meter.
The invention has the beneficial effects that the current signal sampling circuit, the current signal filtering circuit, the current signal conditioning circuit, the current signal comparison circuit and the overcurrent detection comparison output circuit are adopted; the current signal sampling circuit is suitable for receiving an externally input current signal; the output end of the current signal sampling circuit is connected with the input end of the current signal filtering circuit; the output end of the current signal filtering circuit is connected with the input end of the current signal conditioning circuit; the output end of the current signal conditioning circuit is connected with the input end of the current signal comparison circuit; the output end of the current signal comparison circuit is connected with the input end of the overcurrent detection comparison output circuit; the output signal of the overcurrent detection comparison output circuit is used as an input signal for CPU overcurrent detection judgment; the multi-path sampling resistor is selected as a relay, and the rapid real-time sampling, accurate judgment and timely protection of external current signals are realized by matching an amplifying and conditioning circuit, a full-wave rectifying circuit and a two-stage comparator circuit.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic block diagram of a wide range over-current detection protection circuit for a power meter of the present invention;
fig. 2 is a specific circuit diagram of a wide range over-current detection protection circuit for a power meter according to the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In this embodiment, the current signal sampling circuit is adapted to convert an externally input current signal into a voltage signal; the current signal filtering circuit carries out filtering treatment on the voltage signal obtained by sampling and carries out primary overcurrent protection; the current signal conditioning circuit is suitable for adjusting the amplitude and the phase of an output signal of the current signal filtering circuit; the current signal comparison circuit is suitable for comparing the voltage signal after input sampling conditioning with a set overcurrent reference voltage to obtain a comparison signal after comparison, and is suitable for realizing overcurrent detection under different measuring ranges by adopting a multi-range matching method; the over-current detection comparison output circuit is suitable for completing conversion of the level signal according to the over-current detection comparison signal, so that the level signal meets the pin level detection requirement of the CPU of the microprocessor.
In this embodiment, as shown in fig. 2, the current signal sampling circuit is responsible for converting an externally input current signal into a voltage signal through a suitable sampling resistor, and is used as a processing signal of a subsequent circuit, and the current signal sampling circuit includes: a positive power supply VCC, a first RELAY RELAY1, a first current sampling resistor RS1 and a second current sampling resistor RS2; the positive end of the externally input current signal is connected with one end of a first current sampling resistor, the positive end of the externally input current signal is simultaneously connected with one end of the first current sampling resistor, the positive end of the externally input current signal is simultaneously connected with one end of a first resistor R1, the negative end of the externally input current signal is connected with the input end of a first relay, the negative end of the externally input current signal is simultaneously connected with a signal ground GND, the other end of the first current sampling resistor is connected with a normally closed output end of the first relay, the other end of the second current sampling resistor is connected with a normally open output end of the first relay, the high end of a coil power supply of the first relay is connected with a positive power supply VCC, the low end of the coil power supply of the first relay is connected with one end of a seventeenth resistor R17, and the low end of the coil power supply of the first relay is simultaneously connected with a CPU pin.
The current signal filter circuit carries out filtering treatment on the sampled voltage signal to filter useless high-frequency noise signals, so that the signal for subsequent treatment is purer, meanwhile, the current signal filter circuit has primary overcurrent protection function, clamps and protects the voltage signal through a voltage stabilizing tube to avoid impact damage to a rear device, and the current signal filter circuit comprises a positive power supply VCC, a negative power supply VEE, a first resistor, a first capacitor C1, a first voltage stabilizing tube D1, a second voltage stabilizing tube D2, a second capacitor C2, a thirteenth capacitor C13 and a first operational amplifier U1; the other end of the first resistor is connected with one end of the first capacitor, the other end of the first resistor is simultaneously connected with one end of the first voltage stabilizing tube, the other end of the first resistor is simultaneously connected with one end of the second voltage stabilizing tube, the other end of the first resistor is simultaneously connected with the homodromous input end of the first operational amplifier, the other end of the first capacitor is connected with the signal ground GND, the other end of the first voltage stabilizing tube is connected with the signal ground GND, the reverse input end of the first operational amplifier is connected with the output end of the first operational amplifier, the output end of the first operational amplifier is simultaneously connected with the homodromous input end of the second operational amplifier, one end of the second capacitor is connected with the negative power supply VEE, the other end of the second capacitor is connected with the signal ground GND, one end of the thirteenth capacitor is connected with the positive power supply VCC, and the other end of the thirteenth capacitor is connected with the signal ground GND.
The current signal conditioning circuit is mainly responsible for adjusting the amplitude and the phase of an output signal of the current signal filtering circuit, and a diode and an operational amplifier are utilized to adjust a sine waveform with lower amplitude into a half-wave sine signal with proper amplitude; the circuit comprises a positive power supply VCC, a negative power supply VEE, a second operational amplifier U2, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9 and a third operational amplifier U3; the reverse input end of the second operational amplifier is connected with one end of the second resistor, the reverse input end of the second operational amplifier is simultaneously connected with the anode of the third diode, the reverse input end of the second operational amplifier is simultaneously connected with one end of the fifth capacitor, the reverse input end of the second operational amplifier is simultaneously connected with one end of the third resistor, the other end of the second resistor is connected with the signal ground GND, the output end of the second operational amplifier is connected with the cathode of the third diode, the output end of the second operational amplifier is simultaneously connected with the anode of the fourth diode, the output end of the second operational amplifier is simultaneously connected with the other end of the fifth capacitor, the other end of the third resistor is simultaneously connected with the reverse input end of the third operational amplifier, the other end of the third resistor is simultaneously connected with one end of the sixth capacitor, the other end of the fourth diode is simultaneously connected with one end of the fifth resistor, the other end of the fourth diode is simultaneously connected with the signal ground GND, the output end of the third operational amplifier is simultaneously connected with the other end of the seventh resistor, the other end of the fourth resistor is simultaneously connected with the signal ground, the other end of the ninth resistor is simultaneously connected with the ninth capacitor, the other end of the eighth resistor is simultaneously connected with the negative end of the sixth capacitor is simultaneously connected with the sixth capacitor, the other end of the eighth capacitor is connected to the signal ground GND.
The current signal comparison circuit is a comparison circuit based on a current reference, and the comparison circuit is used for comparing the voltage signal after input sampling conditioning with the set overcurrent reference voltage to obtain a comparison signal for overcurrent detection after comparison, and meanwhile, the overcurrent detection under different measuring ranges is realized by adopting a multi-range matching method, so that the overcurrent judgment under the current condition in a wide range can be realized; the circuit comprises a positive power supply VCC, a negative power supply VEE, a seventh resistor R7, a seventeenth resistor R17, a first triode Q1, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a tenth capacitor C10, an eleventh capacitor C11, a fourth operational amplifier U4 and a fifth operational amplifier U5; the other end of the seventh resistor is connected with the collector of the first triode, the other end of the seventeenth resistor is connected with the base of the first triode, the emitter of the first triode is connected with the signal ground GND, one end of the ninth resistor is connected with the positive power supply VCC, the other end of the ninth resistor is connected with one end of the eighth resistor, the other end of the ninth resistor is simultaneously connected with the homodromous input end of the fourth operational amplifier, the other end of the eighth resistor is connected with the signal ground GND, the output end of the fourth operational amplifier is connected with one end of the tenth resistor, the output end of the fourth operational amplifier is simultaneously connected with the other end of the eleventh resistor, the output end of the fourth operational amplifier is simultaneously connected with the reverse input end of the fifth operational amplifier, the other end of the tenth resistor is connected with the positive power supply VCC, the homodromous input end of the fifth operational amplifier is simultaneously connected with one end of the thirteenth resistor, the other end of the twelfth resistor is connected with the positive power supply, the other end of the thirteenth resistor is connected with the signal ground GND, the output end of the fifth operational amplifier is connected with one end of the fifteenth resistor, and the other end of the eleventh capacitor is connected with the signal ground GND.
The overcurrent detection comparison output circuit finishes the conversion of the level signal and meets the pin level detection requirement of the CPU of the microprocessor; the circuit comprises a positive power supply VCC, a negative power supply VEE, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a second triode Q2 and a twelfth capacitor C12; the other end of the fifteenth resistor is connected with one end of the fourteenth resistor, the other end of the fifteenth resistor is simultaneously connected with the base electrode of the second triode, the other end of the fourteenth resistor is connected with the positive power supply VCC, the collector electrode of the second triode is connected with the positive power supply VCC, the emitter electrode of the second triode is connected with one end of the sixteenth resistor, the other end of the sixteenth resistor is connected with one end of the twelfth capacitor, the other end of the sixteenth resistor is simultaneously connected with the external microprocessor, and the other end of the twelfth capacitor is connected with the signal ground GND.
In this embodiment, the first relay, the first sampling resistor, and the second sampling resistor form a current signal sampling circuit, and firstly, a suitable current range is selected, and an external current signal is converted into a voltage signal Vsg1 through the current sampling resistor; the first resistor, the first capacitor, the first voltage stabilizing tube, the second voltage stabilizing tube and the first operational amplifier form a current signal filter circuit, other useless noise signals in the voltage signal Vsg1 are filtered, meanwhile, the voltage stabilizing tube plays a role in clamping and limiting the voltage signal, a later-stage circuit is better protected, damage to a later-stage device caused by overcurrent is avoided, and the current signal filter circuit obtains a purer signal Vsg2; the second operational amplifier, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor and the third operational amplifier form a current signal conditioning circuit, the amplitude and the phase of an output signal Vsg2 of the current signal filtering circuit are adjusted, a diode and the operational amplifier are utilized to adjust a sine waveform with lower amplitude into a half-wave sine signal Vsg3 with higher amplitude, and the conditioned Vsg3 signal is used as an input comparison signal of the current signal comparison circuit; a seventh resistor, a seventeenth resistor, a first triode, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a tenth capacitor, an eleventh capacitor, a fourth operational amplifier and a fifth operational amplifier form a current signal two-stage comparison circuit, a voltage division comparison value formed by the eighth resistor and the ninth resistor is used as a comparison threshold value of a first comparator formed by the fourth operational amplifier, a comparison signal Vsg5 is output, and a voltage division comparison value formed by the twelfth resistor and the thirteenth resistor is used as a comparison threshold value of a second comparator formed by the fifth operational amplifier, and a comparison signal Vsg6 is output; the fourteenth resistor, the fifteenth resistor, the sixteenth resistor, the second triode and the twelfth capacitor form an overcurrent detection comparison output circuit, level signal conversion is completed, an output signal Vsg7 is sent to an external microprocessor CPU for detection processing, and whether external current is overcurrent is judged; the external current signal can be detected rapidly and accurately in real time, when the overcurrent signal is generated, the current range is automatically switched through the hardware circuit, and meanwhile, the accurate overcurrent detection and judgment of different current ranges are met.
Specifically, the current signal sampling circuit is based on a relay to current sampling resistors with different current ranges, and converts a current signal into a voltage signal through the current sampling resistor and sends the voltage signal to the current signal filtering circuit; the current signal filter circuit is mainly based on an RC filter circuit, an overvoltage clamping protection circuit and a follower circuit, filters an input signal to obtain a purer alternating current signal, and outputs the purer alternating current signal to the current signal conditioning circuit through the follower circuit with high input impedance; the current signal conditioning circuit amplifies and full-wave rectifies full-sine signals containing positive and negative potentials into pulsating waveforms based on the operational amplification circuit and the rectifier diode, and sends the pulsating waveforms into the current signal comparison circuit; the current signal comparison circuit is mainly composed of two stages of comparators, wherein if an input comparison signal is smaller than a comparison threshold value, the second stage of comparator outputs a low level, and if the input comparison signal is larger than the comparison threshold value, the second stage of comparator outputs a high level; the overcurrent detection comparison output circuit converts the comparison output signal of the current signal comparison circuit into a level signal which can be processed by an external microprocessor CPU, the CPU judges whether the external circuit is overcurrent or not according to the output high-low level, if the external circuit is overcurrent, the external current is overcurrent, the CPU outputs a control signal CTRL_CPU to control a relay of the current signal sampling circuit, a current sampling resistor of the next current measuring range is selected, and meanwhile, the CPU outputs the control signal CTRL_CPU to control a voltage division proportion triode of the current signal comparison circuit, so that the signal amplification proportion under the current measuring range is obtained again to be used as the comparison signal of the current measuring range.
RELAY1 is RELAY type number 832A, U1, U2, U3 are integrated operational amplifier type number UPC812, U4, U5 are comparator chip type number LM393, Q1, Q2 are NPN triode type number 2SC2712, D1, D2 are clamp protection voltage regulator type number LM385-1.2V, D3, D4 are protection diode type number 4148, RS1, RS2 are current sampling resistors, R1 to R16 are resistors, and C1 to C13 are capacitors.
The RELAY1 RELAY selects a current sampling resistor according to a control signal CTRL_CPU from the CPU, starts to select a small current range, the control signal CTRL_CPU of the CPU is low, and selects a current sampling resistor RS1, and a voltage signal obtained by the current sampling resistor is as follows:
cut-off frequency of R1 and C1 components
Is higher than the frequency f in the signal Vsg1 c The signals of the D1 and D2 voltage stabilizing tubes are filtered, the input Vsg1 signals are clamped, the safe input of the later-stage devices is protected, when the input Vsg1 signals exceed the range of the voltage stabilizing tube, the output Vsg2 signals are the voltage stabilizing value of the voltage stabilizing tube, and when the input Vsg1 signals do not exceed the voltage stabilizing value of the voltage stabilizing tube, the later-stage circuits can obtain purer sinusoidal signals Vsg 2. U2, U3, R2, R3, R4, R5 constitute the cascade amplifier, and C5, C6 play the frequency compensation effect of operational amplifier, prevent the operational amplifier self-excitation that great gain leads to, and D3, D4 rectify the signal, will positive and negative sinusoidal signal full wave rectification become positive semi-axis half-wave sinusoidal signal Vsg3, then output signal Vsg3 and input signal Vsg 2's amplitude operational relation is:
because the small current range is selected initially, the base control signal of the triode Q1 is low level, the triode Q1 is not conducted, and the signal Vsg4 is the cut-off frequency formed by the signal Vsg3 through R6 and C9
The signal Vsg4 substantially coincides with the signal Vsg 3; the signal Vsg4 is sent to a lower-stage comparison circuit for processing, U4, U5, R8, R9, R10, R11, R12 and R13 form a two-stage comparator, and the proportion of R8 and R9 is divided to obtain the comparison of a first-stage comparatorThe threshold is:
the comparison threshold value obtained by dividing the ratio of R12 to R13 is as follows:
if the external current is not flowing excessively, the signal Vsg4 is smaller than the signal Vsg8, the output comparison signal Vsg5 of the first-stage comparator is at high level, the output comparison signal Vsg6 of the second-stage comparator is at low level, the level conversion circuit is composed of R14, R15, R16, Q2 and C12, the comparison signal Vsg6 is at low level to make the transistor Q2 non-conductive, and the final output signal Vsg7 is at low level to be sent to the CPU for detection.
If the external current flows, the signal Vsg4 is greater than the signal Vsg8 and the output comparison signal Vsg5 of the first stage comparator is at low level, the output comparison signal Vsg6 of the second stage comparator is at high level, the triode Q2 is turned on, the final output signal Vsg7 is at high level, the final output signal is sent to the CPU for detection, the CPU current range control signal ctrl_cpu is at high level, the relay switches and selects the large current range sampling resistor RS2, the sampling voltage signal vsg1=rs2×i in The high-level control signal ctrl_cpu turns on the transistor Q1, and the signal Vsg4 is no longer equal to the signal Vsg3, but matches the current large current range value, so as to satisfy the following operational relationship:
Z c the capacitance impedance value of the capacitor C9 satisfies the following operational relationship:
then
In its simplest form:
if the signal Vsg4 is smaller than the signal Vsg8, the output comparison signal Vsg5 of the first stage comparator is at a high level, the output comparison signal Vsg6 of the second stage comparator is at a low level, so that the triode Q2 is not conducted, the final output signal Vsg7 is at a low level, and the external current does not exceed the overcurrent threshold of the current large current range; if the signal Vsg4 is greater than the signal Vsg8, the output comparison signal Vsg5 of the first stage comparator is at a low level, the output comparison signal Vsg6 of the second stage comparator is at a high level, and the transistor Q2 is turned on, the final output signal Vsg7 is at a high level, and the external current exceeds the overcurrent threshold of the current large current range. The automatic switching selection of the plurality of process sampling resistors completes the function of real-time and rapid detection of current under different external overcurrent conditions.
In this embodiment, the method for obtaining the output comparison signal according to the input comparison signal includes: outputting a comparison signal Vsg5 according to comparison thresholds of the current signal two-stage comparison circuit and the first comparator; the comparison signal Vsg6 is output according to the comparison threshold values of the current signal two-stage comparison circuit and the second comparator.
In the present embodiment, the signal Vsg7 is output after the level signal is converted; the Vsg7 is output to an external microprocessor CPU for detection processing to determine whether an external current is flowing. Specific protection methods are described in detail in example 1, and will not be repeated.
Example 3
On the basis of embodiment 1, embodiment 3 further provides a wide-range overcurrent detection protection device, which includes: the wide range overcurrent detection protection circuit for a power meter in embodiment 1.
In summary, the invention uses the current signal sampling circuit, the current signal filtering circuit, the current signal conditioning circuit, the current signal comparing circuit and the overcurrent detection comparing output circuit; the current signal sampling circuit is suitable for receiving an externally input current signal; the output end of the current signal sampling circuit is connected with the input end of the current signal filtering circuit; the output end of the current signal filtering circuit is connected with the input end of the current signal conditioning circuit; the output end of the current signal conditioning circuit is connected with the input end of the current signal comparison circuit; the output end of the current signal comparison circuit is connected with the input end of the overcurrent detection comparison output circuit; the output signal of the overcurrent detection comparison output circuit is used as an input signal for CPU overcurrent detection judgment; the multi-path sampling resistor is selected as a relay, and the rapid real-time sampling, accurate judgment and timely protection of external current signals are realized by matching an amplifying and conditioning circuit, a full-wave rectifying circuit and a two-stage comparator circuit.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other manners as well. The apparatus embodiments described above are merely illustrative, for example, of the flowcharts and block diagrams in the figures that illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules in the embodiments of the present invention may be integrated together to form a single part, or each module may exist alone, or two or more modules may be integrated to form a single part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (10)
1. A wide range overcurrent detection protection circuit for a power meter, comprising:
the current signal sampling circuit, the current signal filtering circuit, the current signal conditioning circuit, the current signal comparison circuit and the overcurrent detection comparison output circuit;
the current signal sampling circuit is suitable for receiving an externally input current signal;
the output end of the current signal sampling circuit is connected with the input end of the current signal filtering circuit;
the output end of the current signal filtering circuit is connected with the input end of the current signal conditioning circuit;
the output end of the current signal conditioning circuit is connected with the input end of the current signal comparison circuit;
the output end of the current signal comparison circuit is connected with the input end of the overcurrent detection comparison output circuit;
and the output signal of the overcurrent detection comparison output circuit is used as an input signal for CPU overcurrent detection judgment.
2. A wide range over-current detection protection circuit for a power meter as set forth in claim 1, wherein,
the current signal sampling circuit is suitable for converting an externally input current signal into a voltage signal.
3. A wide range over-current detection protection circuit for a power meter as set forth in claim 2, wherein,
and the current signal filtering circuit performs filtering processing on the sampled voltage signal and performs primary overcurrent protection.
4. A wide range over-current detection protection circuit for a power meter as set forth in claim 3, wherein,
the current signal conditioning circuit is suitable for adjusting the amplitude and the phase of the output signal of the current signal filtering circuit.
5. A wide range over-current detection protection circuit for a power meter as set forth in claim 4, wherein,
the current signal comparison circuit is suitable for comparing the voltage signal after input sampling conditioning with a set overcurrent reference voltage to obtain a comparison signal after comparison and
the current signal comparison circuit is suitable for detecting overcurrent under different measuring ranges by adopting a multi-range matching method.
6. A wide range over-current detection protection circuit for a power meter as set forth in claim 5, wherein,
the over-current detection comparison output circuit is suitable for completing conversion of the level signal according to the over-current detection comparison signal, so that the level signal meets the pin level detection requirement of the CPU of the microprocessor.
7. A wide-range overcurrent detection protection method using the wide-range overcurrent detection protection circuit for a power meter according to claim 1, comprising:
converting a current signal into a voltage signal
Filtering noise signals of the voltage signals to obtain purer signals;
the method comprises the steps of adjusting amplitude and phase of a purer signal, adjusting a sine waveform with lower amplitude to a half-wave sine signal with higher amplitude, and taking the half-wave sine signal as an input comparison signal of a current signal comparison circuit;
obtaining an output comparison signal according to the input comparison signal;
and performing level signal conversion according to the output comparison signal.
8. The broad range over-current detection protection method of claim 7, wherein,
the method for obtaining the output comparison signal according to the input comparison signal comprises the following steps:
outputting a comparison signal Vsg5 according to comparison thresholds of the current signal two-stage comparison circuit and the first comparator;
the comparison signal Vsg6 is output according to the comparison threshold values of the current signal two-stage comparison circuit and the second comparator.
9. The broad range over-current detection protection method of claim 8, wherein,
outputting a signal Vsg7 after the level signal is converted;
the Vsg7 is output to an external microprocessor CPU for detection processing to determine whether an external current is flowing.
10. A wide range overcurrent detection protection device, comprising:
the broad range over-current detection protection circuit for a power meter of claim 1.
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