CN113281559B - High-reliability overcurrent fault detection circuit - Google Patents
High-reliability overcurrent fault detection circuit Download PDFInfo
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- CN113281559B CN113281559B CN202110527652.0A CN202110527652A CN113281559B CN 113281559 B CN113281559 B CN 113281559B CN 202110527652 A CN202110527652 A CN 202110527652A CN 113281559 B CN113281559 B CN 113281559B
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The invention discloses a high-reliability overcurrent fault detection circuit which comprises a reference source generation circuit, a differential amplification circuit, a window comparison circuit, a signal conditioning circuit and a logic conversion circuit, wherein the reference source generation circuit comprises a voltage stabilizing tube, a current limiting resistor, a reference voltage regulator, a voltage dividing resistor, an operational amplifier and the like. The invention reduces the system cost, improves the suppression capability of common mode signals, effectively improves the common mode suppression ratio, can well suppress temperature drift, and improves the precision and anti-interference performance of fault detection; the low-pass filter circuit has the function of latching fault signals, so that the problem of wave loss caused by too small effective level width of the fault signals in the detection process is avoided, the reliability of fault detection is improved, and the anti-interference performance of the circuit is further improved.
Description
Technical Field
The invention relates to the technical field of frequency converters, in particular to a high-reliability overcurrent fault detection circuit.
Background
In a low-voltage frequency converter, in order to detect three-phase output current in real time, only a detection circuit of two-phase current is needed to be designed, a calculated value can be obtained by vector sum of the two-phase current in detection of the third-phase output current, and the main purpose of the third-phase output current detection circuit is to avoid that an inverter bridge is invalid due to continuous large current generated when the third-phase output is short-circuited to ground. The inverter bridge output overcurrent fault detection circuit generally converts a current signal into a voltage signal by a current sensor, and a comparator acquires the voltage signal output by the current sensor and compares the voltage signal with a reference voltage and then outputs an overcurrent fault signal, which is shown in fig. 6 in detail, specifically: the output end of the current sensor U4 is connected with the reverse input end of the comparator U5A, a resistor R28 is connected in series between the output end of the current sensor U4 and the reverse input end of the comparator U5B, a resistor R30 is connected in series between the output end of the current sensor U4 and the reverse input end of the comparator U5A, the power end of the resistor R32 is connected with the positive electrode of the power supply, the other end of the resistor R32 is connected with the same-direction input end of the comparator U5A, one end of the resistor R33 is connected with the same-direction input end of the comparator U5A, the other end of the resistor R33 is connected with the reverse input end of the comparator U5B, one end of the resistor R31 is connected with the same-direction input end of the comparator U5A, the other end of the resistor R29 is connected with the same-direction input end of the comparator U5B, the other end of the resistor R29 is connected with the output end of the comparator U5B, the other end of the filter circuit is connected with the other end of the capacitor C23, the other end of the capacitor C23 is connected with the other end of the capacitor C5B, and the other end of the capacitor C is connected with the other end of the capacitor C25, and the capacitor C is connected with the other end of the capacitor C25 to the other end of the capacitor C is connected with the capacitor C5B.
The circuit adopts the scheme of the current sensor and the comparator, can realize the overcurrent fault detection function, but has higher cost by using the current sensor, and is uneconomical only when being used for overcurrent fault detection.
Disclosure of Invention
The invention aims to provide a high-reliability overcurrent fault detection circuit, which can reliably realize the overcurrent fault detection function and reduce the system cost compared with the technical scheme adopting a current sensor when being used for detecting the output overcurrent fault of a frequency converter.
In order to achieve the above purpose, the present invention provides the following technical solutions:
The utility model provides a high reliability's overcurrent fault detection circuit, includes current input, reference source generation circuit, differential amplifier circuit, window comparison circuit, signal conditioning circuit, logic conversion circuit and signal output interface, the output of reference source generation circuit is connected with differential amplifier circuit, window comparison circuit electricity, differential amplifier circuit's input is connected with the current input electricity, differential amplifier circuit's output is connected with window comparison circuit's input electricity, window comparison circuit's output is connected with signal conditioning circuit's input electricity, signal conditioning circuit's output is connected with logic conversion circuit electricity, logic conversion circuit connects signal output interface and output fault signal.
Preferably, the reference source generating circuit comprises a first regulated power supply, a second regulated power supply, a voltage dividing resistor and an operational amplifier U2B, wherein the first regulated power supply comprises a resistor R1, a capacitor C1, a zener diode ZD1 and a capacitor C2, and the second regulated power supply comprises a filter capacitor C3, a current limiting resistor R2, a reference voltage regulator U1, a voltage dividing resistor R3 and a voltage dividing resistor R4;
Preferably, the resistor R1 is electrically connected to the positive electrode of the first regulated power supply, the other end is grounded, the capacitor C1 is electrically connected in parallel with the resistor R1, the zener diode ZD1 is electrically connected to the negative electrode of the first regulated power supply, the other end is grounded, the capacitor C2 is electrically connected in parallel with the zener diode ZD1, one end of the resistor R2 is electrically connected to the positive electrode of the first regulated power supply, the other end is electrically connected to the positive electrode of the second regulated power supply, one end of the resistor R3 is electrically connected to the positive electrode of the second regulated power supply, the other end is electrically connected to the reference end of the reference voltage regulator U1, one end of the resistor R4 is electrically connected to the reference end of the reference voltage regulator U1, the other end is grounded, and the cathode of the reference voltage regulator U1 is electrically connected to the positive electrode of the second regulated power supply; one end of the capacitor C4 is electrically connected with the positive electrode of the second regulated power supply, the other end of the capacitor C4 is grounded, one end of the resistor R5 is electrically connected with the positive electrode of the second regulated power supply, the other end of the resistor R5 is electrically connected with the homodromous input end of the operational amplifier U2B, one end of the resistor R6 is electrically connected with the homodromous input end of the operational amplifier U2B, the other end of the resistor R6 is grounded, and the reverse input end of the operational amplifier U2B is electrically connected with the output end of the operational amplifier U2B;
Preferably, the differential amplifying circuit includes a sampling resistor R7, a differential resistor R8, a differential resistor R9, a differential resistor R10, a differential resistor R11, a capacitor C5, a capacitor C6, and an operational amplifier U2A, wherein one end of the sampling resistor R7 is electrically connected to one end of the differential resistor R8, the other end is electrically connected to one end of the differential resistor R9, the other end of the differential resistor R8 is electrically connected to an inverting input end of the operational amplifier U2A, the other end of the resistor R9 is electrically connected to a co-directional input end of the operational amplifier U2A, the differential resistor R10 is electrically connected to a co-directional input end of the operational amplifier U2A, the other end is grounded, one end of the differential resistor R11 is electrically connected to an inverting input end of the operational amplifier U2A, the other end is electrically connected to an output end of the operational amplifier U2A, the capacitor C5 is parallel to the differential resistor R10, and the capacitor C6 is parallel to the differential resistor R11;
Preferably, the differential amplifying circuit further includes a filter capacitor C7, a filter capacitor C8, and a filter capacitor C9, where one end of the filter capacitor C7 is electrically connected to the output of the operational amplifier U2B, and the other end of the filter capacitor C8 is electrically connected to the positive power supply of the operational amplifier U2A, and the other end of the filter capacitor C9 is grounded, and the other end of the filter capacitor C9 is electrically connected to the negative power supply of the operational amplifier U2A;
preferably, the window comparison circuit comprises a comparator, a low-pass filter group, a hysteresis feedback resistor, an overcurrent reference voltage dividing resistor and a filter capacitor;
Preferably, the comparator comprises a comparator U3A and a comparator U3B, the low-pass filter group comprises a first low-pass filter group and a second low-pass filter group, the first low-pass filter group comprises a resistor R15 and a capacitor C10, the second low-pass filter group comprises a resistor R17 and a capacitor C12, one end of the resistor R15 is electrically connected with the output end of the differential amplifying circuit, the other end of the resistor R15 is electrically connected with the inverting input end of the comparator U3A, one end of the capacitor C10 is electrically connected with the inverting input end of the comparator U3A, the other end of the capacitor C10 is grounded, one end of the resistor R17 is electrically connected with the output end of the differential amplifying circuit, the other end of the resistor R17 is electrically connected with the homodromous input end of the comparator U3B, and the other end of the capacitor C12 is grounded;
preferably, the hysteresis feedback resistor comprises a resistor R16 and a resistor R18, wherein one end of the resistor R16 is electrically connected with the same-direction input end of the comparator U3A, the other end of the resistor R16 is electrically connected with the output end of the comparator U3A, one end of the resistor R18 is electrically connected with the same-direction input end of the comparator U3B, and the other end of the resistor R18 is electrically connected with the output end of the comparator U3B;
preferably, the reference voltage dividing resistor comprises a resistor R12, a resistor R13 and a resistor R14, wherein one end of the resistor R12 is electrically connected with the positive electrode of the second regulated power supply, the other end of the resistor R12 is electrically connected with the same-direction input end of the comparator U3A, one end of the resistor R13 is electrically connected with the same-direction input end of the comparator U3A, the other end of the resistor R13 is electrically connected with the reverse input end of the comparator U3B, and one end of the resistor R14 is electrically connected with the reverse input end of the comparator U3B;
In order to achieve a better technical effect, the window comparison circuit further comprises a filter capacitor C14, a filter capacitor C11 and a filter capacitor C13, one end of the filter capacitor C14 is electrically connected with the power supply positive electrode of the comparator U3A and the power supply positive electrode of the comparator U3B, the other end of the filter capacitor C11 is grounded, one end of the filter capacitor C11 is electrically connected with the homodromous input end of the comparator U3A, the other end of the filter capacitor C13 is electrically connected with the reverse input end of the comparator U3B, and the other end of the filter capacitor C is grounded;
In order to achieve better technical effects, the signal conditioning circuit comprises a resistor R19, a resistor R20, a capacitor C15, a resistor R21, a resistor R22, a transistor Q1, a resistor R23, a capacitor C16 and a photo-coupler PC1, wherein one end of the resistor R19 is electrically connected with the positive electrode of the first voltage stabilizing power supply, the other end of the resistor R19 is electrically connected with the base electrode of the transistor Q1, the other end of the resistor R20 is electrically connected with the emitter electrode of the transistor Q1, the capacitor C15 is electrically connected with the resistor R20 in parallel, the base electrode of the transistor Q1 is electrically connected with the output electrode of the comparator U3A and the comparator U3B, one end of the resistor R21 is electrically connected with the positive electrode of the first voltage stabilizing power supply, the other end of the resistor R22 is electrically connected with the collector electrode of the transistor Q1, one end of the resistor R23 is electrically connected with the emitter electrode of the transistor Q1, the other end of the resistor R is grounded, the base electrode of the transistor Q1 is electrically connected with the light emitting diode and the emitter electrode of the photo-coupler PC1 in parallel, and the photo-coupler PC is electrically connected with the photo-coupler PC1 in parallel;
In order to achieve a better technical effect, the logic conversion circuit comprises a signal latching group, a transistor Q2 and a low-pass filter group, wherein the signal latching group comprises a resistor R24, a resistor R25 and a capacitor C17, the low-pass filter group comprises a resistor R26 and a capacitor C18, one end of the resistor R24 is connected with a collector of a phototriode of a photoelectric coupler PC1, the other end of the resistor R24 is electrically connected with a base of the transistor Q2, one end of the resistor R25 is electrically connected with a positive electrode of a first stabilized voltage supply, the other end of the resistor R25 is electrically connected with a base of the transistor Q2, one end of the capacitor C17 is electrically connected with the base of the transistor Q2, the other end of the capacitor C17 is grounded, one end of the capacitor C18 is electrically connected with a collector of the transistor Q2, the other end of the resistor R26 is grounded, and one end of the collector of the resistor Q2 is electrically connected with the other end of the transistor Q2 to output a fault signal;
Compared with the prior art, the invention has the beneficial effects that:
(1) The current signal is converted into a voltage signal through the sampling resistor, the photoelectric coupler is adopted to realize the electric isolation of strong and weak current, the function of replacing the current sensor is realized on the scheme, and the system cost is reduced;
(2) The differential amplifying circuit is introduced, so that the suppression capability of common mode signals is improved, the common mode suppression ratio is effectively improved, the temperature drift can be well suppressed, and the fault detection precision and the anti-interference performance are improved;
(3) The logic conversion circuit is introduced, and through connecting the pull-up resistor outside the fault signal output interface end, the two fault detection modes of overcurrent and signal interface disconnection can be realized, and the logic conversion circuit has the function of fault signal latching, so that the problem of wave loss caused by too small effective level width of the fault signal in the detection process is avoided, the reliability of fault detection is improved, and the anti-interference performance of the circuit is further improved by the low-pass filter circuit.
Drawings
Fig. 1 to 4 are diagrams of an overcurrent fault detection circuit according to embodiment 1 of the present invention;
FIG. 5 is a flow chart of the overcurrent fault detection of the present invention;
FIG. 6 is a prior art overcurrent fault detection circuit diagram;
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the drawings in the embodiments of the present invention, so that those skilled in the art can implement the embodiments according to the description.
Example 1
Referring to fig. 1 to 4, the circuit comprises a current input end, a reference source generating circuit, a differential amplifying circuit, a window comparing circuit, a signal conditioning circuit, a logic conversion circuit and a signal output interface, wherein the output end of the reference source generating circuit is electrically connected with the differential amplifying circuit and the window comparing circuit, the input end of the differential amplifying circuit is electrically connected with the current input end, the output end of the differential amplifying circuit is electrically connected with the input end of the window comparing circuit, the output end of the window comparing circuit is electrically connected with the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is electrically connected with the logic conversion circuit, and the logic conversion circuit outputs fault signals;
The reference source generating circuit comprises a resistor R1 and a capacitor C1, wherein one end of the resistor R1 is connected with a positive electrode (+16VCC) of a first voltage stabilizing power supply, the other end of the resistor R1 is grounded (GND 1), one end of the resistor R1 is grounded (GND 1), the other end of the resistor R4 is connected with a negative electrode (-9 VCC) of the first voltage stabilizing power supply, one end of the capacitor C3 is connected with the positive electrode (+16VCC) of the first voltage stabilizing power supply, the other end of the capacitor C3 is grounded, the current limiting resistor R2 is connected in series between the positive electrode (+16VCC) of the first voltage stabilizing power supply and the positive electrode (+5VCC) of the second voltage stabilizing power supply, the cathode of the resistor U1 is connected with the positive electrode of the second voltage stabilizing power supply, the resistor R3 is connected between the cathode of the reference voltage regulator U1 and the reference end of the resistor R4 is connected in parallel, the other end of the resistor R5 is connected with the other end of the second voltage stabilizing power supply positive electrode (+5VCC) of the operational amplifier U2B in the same direction, the voltage dividing resistor R6 is connected with the other end of the operational amplifier U2B in the same direction, and the output end of the voltage dividing resistor R6 is connected with the output end of the operational amplifier U2B is connected in a short circuit. Reference source generation circuit: the resistances of the resistor R3 and the resistor R4 are equal, and the resistances of the voltage dividing resistor R5 and the voltage dividing resistor R6 are equal.
The differential amplifying circuit comprises a sampling resistor R7 connected in parallel to a current input end, a resistor R8 with one end connected with the sampling resistor R7 and the other end connected with the reverse input end of the operational amplifier U2A, a resistor R9 with one end connected with the sampling resistor R7 and the other end connected with the same direction input end of the operational amplifier U2A, a resistor R11 connected in parallel with the reverse input end and the output end of the operational amplifier U2A, a resistor R10 with one end connected with the same direction input end of the operational amplifier U2A and the other end connected with a reference source (+2.5VREF), a filter capacitor C6 connected in parallel with the resistor R11, a filter capacitor C5 with one end connected with the reference source (+2.5VREF) and the other end grounded, a filter capacitor C8 with one end connected with the positive electrode of the first stabilized power source (+16VCC) and the other end grounded, and a filter capacitor C9 with the other end grounded and the other end connected with the negative electrode (-9) of the first stabilized power source, wherein the positive electrode and the negative electrode of the power source of the operational amplifier U2A are respectively connected with the first stabilized power source (+16) and the negative electrode of the first stabilized power source (-VCC 9). In the differential amplifying circuit: the resistances of the resistor R8 and the resistor R9 are equal, the resistances of the resistor R10 and the resistor R11 are equal, and the capacitances of the capacitor C5 and the capacitor C6 are equal. The differential amplifying circuit improves the amplifying capability of differential mode signals and the inhibiting capability of common mode signals, effectively improves the common mode inhibiting ratio and can well inhibit temperature drift.
The window comparison circuit comprises a resistor R15 with one end connected with the output end of the differential amplification circuit and the other end connected with the reverse input end of the comparator U3A, a resistor R17 with one end connected with the output end of the differential amplification circuit and the other end connected with the homodromous input end of the comparator U3B, a filter capacitor C10 and a filter capacitor C11 with one end connected with the other end grounded of the input end of the comparator U3A, a filter capacitor C12 and a filter capacitor C13 with one end connected with the other end grounded of the input end of the comparator U3B, a resistor R12 with one end connected with the positive pole (+5VCC) of the second stabilized voltage supply and the other end connected with the homodromous input end of the comparator U3A a resistor R14 with one end grounded and the other end connected with the inverting input end of the comparator U3B, a resistor R13 with one end connected with the homodromous input end of the comparator U3A and the other end connected with the inverting input end of the comparator U3B, a resistor R16 connected in parallel with the non-inverting input end and the output end of the comparator U3A, a resistor R18 connected in parallel with the non-inverting input end and the output end of the comparator U3B, a filter capacitor C14 with one end connected with the positive pole (+ 16 VCC) of the first stabilized power supply and the other end grounded (GND 1), the power supply anodes and the power supply cathodes of the comparator U3A and the comparator U3B are respectively connected with the first stabilized voltage power supply anode (+ 16 VCC) and the ground (GND 1).
The signal conditioning circuit comprises a photocoupler PC1, a resistor R19, a transistor Q1, a resistor R20, a capacitor C15, a resistor R21 and a resistor R22, a resistor R23, a capacitor C18 and a resistor R26, wherein one end of the resistor R19 is connected with the positive pole of a first stabilized voltage power supply (+16VCC) and the other end of the first stabilized voltage power supply (+16VCC), the other end of the first stabilized voltage power supply is connected with the output end of a comparator, the base electrode of the photo-transistor is connected with the output end of the comparator, the collector electrode of the photo-transistor is connected with the other end of the photo-transistor of the photocoupler PC1, the resistor R24 is connected with the base electrode of the transistor Q2 in parallel, the resistor R25 is connected with the other end of the positive pole of the power supply (+5VDD), the capacitor C17 is connected with the other end of the base electrode of the transistor, the capacitor C22 is connected with the other end of the base electrode of the transistor, the capacitor C18 is connected with the other end of the ground, the other end of the transistor Q2 is connected with the other end of the base electrode of the photo-transistor, and the collector electrode of the other end of the photo-transistor Q2 is connected with the collector electrode of the photo-transistor. The resistor R24, the resistor R25 and the capacitor C17 form a fault signal latch circuit, so that the effective level width of a fault signal is improved, and the reliability of fault detection is improved. Meanwhile, the transistor Q2 converts the fault signal from a low level to a high resistance state, the high efficiency of the fault signal is realized by externally connecting a pull-up resistor at the signal interface end, and the two fault detection functions of overcurrent and signal interface disconnection are provided. In addition, the resistor R26 and the capacitor C18 form a low-pass filter circuit, and electrostatic protection is formed on the collector of the transistor Q2 at the fault signal interface end.
The circuit for detecting the overcurrent faults by applying the embodiment is characterized in that the details are as follows:
the circuit design parameter calculation formula is as follows:
by setting the sampling resistor R7, the differential input voltage calculation formula 1) of the differential amplifying circuit can be obtained:
Ui n＝R7*I i n 1)
wherein, ii n is the actual detection current, ui n is the voltage at two ends of the sampling resistor R7;
calculation formula 2 of the output voltage and the input voltage of the differential amplification circuit):
Uo1＝Ui n*R11/R8+VREF 2)
wherein Uo1 is the differential amplifying circuit output voltage, R11 and R8 are differential amplifying resistors, and r11=r10, r9=r8, vref=2.5v;
calculation formula 3) of the overcurrent reference high value of the window comparison circuit:
VOCREFH＝VCC*(R13+R14)/(R12+R13+R14)3)
calculation formula 4) of the overcurrent reference low value of the window comparison circuit:
VOCREFL＝VCC*R14/(R12+R13+R14)4)
Wherein V OCREFH is an overcurrent reference high value, V OCREFL is an overcurrent reference low value, vcc=5v, R12, R13 and R14 are voltage dividing resistors, and r12=r14, V OCREFH+VOCREFL =5v;
Calculation formula 5 of fault current set point):
IOC＝(VOCREF-VREF)/(R11/R8)/R7 5)
Wherein I OC is the fault current set point;
A fault signal latch circuit is composed of a resistor R24, a resistor R25 and a capacitor C17, and the resistance values of the resistor R24 and the resistor R25 are set to satisfy the relation 6):
R25>20*R24 6)
and resistor R25 and capacitor C17 are set to satisfy relation 7):
VCC*(1-e-t/(R25*C17))<0.7 7)
wherein t is a set minimum fault latch time theoretical value, vcc=5v;
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
The applicant has further stated that the present invention is described by the above examples as to the implementation method and apparatus structure of the present invention, but the present invention is not limited to the above embodiments, i.e. it does not mean that the present invention must be implemented by the above methods and structures. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions for the implementation method selected for the present invention, addition of steps, selection of specific modes, etc., fall within the scope of the present invention and the scope of the disclosure.
The present invention is not limited to the above embodiments, and all modes of achieving the object of the present invention by adopting the structure and method similar to those of the present invention are within the scope of the present invention.
Claims (3)
1. A high-reliability overcurrent fault detection circuit is characterized in that: comprises a current input end, a reference source generating circuit, a differential amplifying circuit, a window comparing circuit, a signal conditioning circuit, a logic conversion circuit and a signal output interface, wherein the output end of the reference source generating circuit is electrically connected with the differential amplifying circuit and the window comparing circuit, the input end of the differential amplifying circuit is electrically connected with the current input end, the output end of the differential amplifying circuit is electrically connected with the input end of the window comparison circuit, the output end of the window comparison circuit is electrically connected with the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is electrically connected with the logic conversion circuit, and the output end of the logic conversion circuit is connected with the signal output interface;
the reference source generating circuit comprises a first voltage stabilizing power supply, a second voltage stabilizing power supply, a voltage dividing resistor and an operational amplifier U2B, wherein the first voltage stabilizing power supply comprises a resistor R1, a capacitor C1, a voltage stabilizing diode ZD1 and a capacitor C2, and the second voltage stabilizing power supply comprises a filter capacitor C3, a current limiting resistor R2, a reference voltage regulator U1, a voltage dividing resistor R3 and a voltage dividing resistor R4;
The resistor R1 is electrically connected with the positive electrode of the first regulated power supply, the other end of the resistor R1 is grounded, the capacitor C1 is electrically connected with the negative electrode of the first regulated power supply in parallel, the other end of the resistor is grounded, the capacitor C2 is electrically connected with the positive electrode of the first regulated power supply in parallel, the other end of the resistor R2 is electrically connected with the positive electrode of the second regulated power supply, one end of the resistor R3 is electrically connected with the positive electrode of the second regulated power supply, the other end of the resistor R3 is electrically connected with the reference end of the reference voltage regulator U1, one end of the resistor R4 is electrically connected with the reference end of the reference voltage regulator U1, the other end of the resistor is grounded, and the cathode of the reference voltage regulator U1 is electrically connected with the positive electrode of the second regulated power supply in parallel; one end of the capacitor C4 is electrically connected with the positive electrode of the second regulated power supply, the other end of the capacitor C4 is grounded, one end of the resistor R5 is electrically connected with the positive electrode of the second regulated power supply, the other end of the resistor R5 is electrically connected with the homodromous input end of the operational amplifier U2B, one end of the resistor R6 is electrically connected with the homodromous input end of the operational amplifier U2B, the other end of the resistor R6 is grounded, and the reverse input end of the operational amplifier U2B is electrically connected with the output end of the operational amplifier U2B;
The differential amplifying circuit comprises a sampling resistor R7, a differential resistor R8, a differential resistor R9, a differential resistor R10, a differential resistor R11, a capacitor C5, a capacitor C6 and an operational amplifier U2A, wherein one end of the sampling resistor R7 is electrically connected with one end of the differential resistor R8, the other end of the sampling resistor R8 is electrically connected with one end of the differential resistor R9, the other end of the differential resistor R8 is electrically connected with the reverse input end of the operational amplifier U2A, the other end of the resistor R9 is electrically connected with the same-direction input end of the operational amplifier U2A, the other end of the differential resistor R10 is electrically connected with the reverse input end of the operational amplifier U2A, the other end of the differential resistor R11 is electrically connected with the output end of the operational amplifier U2A, the capacitor C5 is parallel to the differential resistor R10, and the capacitor C6 is parallel to the differential resistor R11;
The differential amplifying circuit further comprises a filter capacitor C7, a filter capacitor C8 and a filter capacitor C9, wherein one end of the filter capacitor C7 is electrically connected with the output of the operational amplifier U2B, the other end of the filter capacitor C8 is grounded, one end of the filter capacitor C8 is electrically connected with the positive electrode of the power supply of the operational amplifier U2A, the other end of the filter capacitor C9 is grounded, and the other end of the filter capacitor C9 is electrically connected with the negative electrode of the power supply of the operational amplifier U2A;
The window comparison circuit comprises a comparator, a low-pass filter group, a hysteresis feedback resistor, an overcurrent reference voltage dividing resistor and a filter capacitor;
the comparator comprises a comparator U3A and a comparator U3B, the low-pass filter group comprises a first low-pass filter group and a second low-pass filter group, the first low-pass filter group comprises a resistor R15 and a capacitor C10, the second low-pass filter group comprises a resistor R17 and a capacitor C12, one end of the resistor R15 is electrically connected with the output end of the differential amplifying circuit, the other end of the resistor R15 is electrically connected with the reverse input end of the comparator U3A, one end of the capacitor C10 is electrically connected with the reverse input end of the comparator U3A, the other end of the capacitor C10 is grounded, one end of the resistor R17 is electrically connected with the output end of the differential amplifying circuit, the other end of the capacitor C12 is electrically connected with the same-direction input end of the comparator U3B, and the other end of the capacitor C12 is grounded;
the hysteresis feedback resistor comprises a resistor R16 and a resistor R18, wherein one end of the resistor R16 is electrically connected with the same-direction input end of the comparator U3A, the other end of the resistor R16 is electrically connected with the output end of the comparator U3A, one end of the resistor R18 is electrically connected with the same-direction input end of the comparator U3B, and the other end of the resistor R18 is electrically connected with the output end of the comparator U3B;
The reference voltage dividing resistor comprises a resistor R12, a resistor R13 and a resistor R14, wherein one end of the resistor R12 is electrically connected with the positive electrode of the second stabilized power supply, the other end of the resistor R12 is electrically connected with the same-direction input end of the comparator U3A, one end of the resistor R13 is electrically connected with the same-direction input end of the comparator U3A, the other end of the resistor R13 is electrically connected with the reverse input end of the comparator U3B, and one end of the resistor R14 is electrically connected with the reverse input end of the comparator U3B;
The window comparison circuit further comprises a filter capacitor C14, a filter capacitor C11 and a filter capacitor C13, one end of the filter capacitor C14 is electrically connected with the power supply anodes of the comparator U3A and the comparator U3B, the other end of the filter capacitor C11 is grounded, one end of the filter capacitor C11 is electrically connected with the homodromous input end of the comparator U3A, the other end of the filter capacitor C13 is grounded, one end of the filter capacitor C13 is electrically connected with the reverse input end of the comparator U3B, and the other end of the filter capacitor C is grounded.
2. The high reliability overcurrent fault detection circuit of claim 1, wherein: the signal conditioning circuit comprises a resistor R19, a resistor R20, a capacitor C15, a resistor R21, a resistor R22, a transistor Q1, a resistor R23, a capacitor C16 and a photoelectric coupler PC1, wherein one end of the resistor R19 is electrically connected with the positive electrode of the first voltage stabilizing power supply, the other end of the resistor R19 is electrically connected with the output of the comparator U3A and the output of the comparator U3B, one end of the resistor R20 is electrically connected with the base electrode of the transistor Q1, the other end of the resistor R20 is electrically connected with the emitter electrode of the transistor Q1, the capacitor C15 is electrically connected with the resistor R20 in parallel, the base electrode of the transistor Q1 is electrically connected with the output of the comparator U3A and the comparator U3B, one end of the resistor R21 is electrically connected with the positive electrode of the first voltage stabilizing power supply, the other end of the resistor R22 is electrically connected with the collector electrode of the transistor Q1, one end of the resistor R23 is electrically connected with the emitter electrode of the transistor Q1, the other end of the resistor R20 is grounded, the light emitting diode of the transistor Q1 and the light emitting diode of the photoelectric coupler PC1 is connected in parallel, and the light emitting diode C16 of the photoelectric coupler PC is connected with the collector electrode of the photoelectric coupler PC.
3. The high reliability overcurrent fault detection circuit of claim 1, wherein: the logic conversion circuit comprises a signal latching group, a transistor Q2 and a low-pass filter group, wherein the signal latching group comprises a resistor R24, a resistor R25 and a capacitor C17, the low-pass filter group comprises a resistor R26 and a capacitor C18, one end of the resistor R24 is electrically connected with a collector of a phototriode of the photoelectric coupler PC1, the other end of the resistor R24 is electrically connected with a base electrode of the transistor Q2, one end of the resistor R25 is electrically connected with a positive electrode of a first stabilized power supply, the other end of the resistor R25 is electrically connected with the base electrode of the transistor Q2, one end of the capacitor C17 is electrically connected with the base electrode of the transistor Q2, the other end of the capacitor C17 is grounded, an emitter of the transistor Q2 is grounded, one end of the capacitor C18 is electrically connected with a collector of the transistor Q2, and the other end of the resistor R26 is electrically connected with the collector of the transistor Q2, and the other end of the resistor R26 outputs a fault signal.
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