WO2022237319A1 - 一种漏电流检测电路、方法及漏电流检测器 - Google Patents

一种漏电流检测电路、方法及漏电流检测器 Download PDF

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Publication number
WO2022237319A1
WO2022237319A1 PCT/CN2022/081474 CN2022081474W WO2022237319A1 WO 2022237319 A1 WO2022237319 A1 WO 2022237319A1 CN 2022081474 W CN2022081474 W CN 2022081474W WO 2022237319 A1 WO2022237319 A1 WO 2022237319A1
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Prior art keywords
leakage current
auxiliary winding
signal
current
switch tube
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PCT/CN2022/081474
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English (en)
French (fr)
Inventor
雷健华
张勇波
马辉
秦赓
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深圳市德兰明海科技有限公司
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Application filed by 深圳市德兰明海科技有限公司 filed Critical 深圳市德兰明海科技有限公司
Priority to EP22773383.9A priority Critical patent/EP4113144A4/en
Priority to JP2022558381A priority patent/JP7476341B2/ja
Priority to US17/944,396 priority patent/US11668762B2/en
Publication of WO2022237319A1 publication Critical patent/WO2022237319A1/zh

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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
    • G01R31/40—Testing power supplies
    • G01R31/42—AC power supplies
    • 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
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the present application relates to the technical field of inverter leakage current detection, for example, to a leakage current detection circuit, method and leakage current detector.
  • the power conversion equipment (such as an inverter) needs to have residual current (leakage current) detection or monitoring protection Function.
  • Embodiments of the present application provide a leakage current detection circuit, method and leakage current detector, which improve the sensitivity of leakage current detection and reduce the cost of leakage current detection.
  • a technical solution adopted in the embodiment of the present application is to provide a leakage current detection circuit, the leakage current detection circuit includes a main winding, an auxiliary winding, a detection module and a signal output module;
  • the main winding is used to connect with the leakage current detection terminal of the device under test, the main winding is coupled with the auxiliary winding, and the auxiliary winding is respectively connected with the signal output module and the detection module;
  • the signal output module is used to output positive and negative pulse signals alternately, so that the auxiliary winding is in a preset state
  • the detection module is configured to detect the current signal of the auxiliary winding when the auxiliary winding is in the preset state, and detect the leakage current of the device under test according to the current signal.
  • the signal output module includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a first control unit;
  • the first end of the first switch tube and the first end of the second switch tube are used to connect to a power supply, and the second end of the first switch tube passes through the detection module and the first end of the auxiliary winding connected, the second end of the first switching tube is also connected to the first end of the fourth switching tube, the second end of the second switching tube is respectively connected to the second end of the auxiliary winding and the first
  • the first ends of the three switch tubes are connected, the second end of the third switch tube and the second end of the fourth switch tube are used for grounding, and the first control unit is connected with the first switch tube and the The control terminals of the second switch tube, the third switch tube, and the fourth switch tube are connected;
  • the first control unit is used to control the on-off states of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube, so as to output the alternating positive and negative pulses signal, wherein the on-off state of the first switching tube is the same as that of the third switching tube, the on-off state of the second switching tube is the same as that of the fourth switching tube, and the first switching tube and the The second switch tube is turned on alternately.
  • the detection module includes a sampling resistor, an operational amplifier and a second control unit;
  • the first end of the auxiliary winding is connected to the signal output module through the sampling resistor, the two input terminals of the operational amplifier are connected to both ends of the sampling resistor, and the output terminal of the operational amplifier is connected to the The second control unit is connected.
  • the detection module is further configured to obtain leakage current information according to the current signal and the duty cycle of the pulse signal, so as to detect the leakage current of the device under test;
  • the detection module is also used to judge whether the current signal is greater than a preset current, and output a leakage current alarm signal when the current signal is greater than the preset current.
  • another technical solution adopted in the embodiment of the present application is: to provide a leakage current detection method, which is applied to the leakage current detection circuit in any of the above-mentioned embodiments, and the method includes: providing the auxiliary winding inputting alternating positive and negative pulse signals, so that the auxiliary winding is in a preset state;
  • the leakage current of the device under test is detected.
  • inputting alternating positive and negative pulse signals to the auxiliary winding so that the auxiliary winding is in a preset state includes:
  • the parameter information includes the magnetic core cross-sectional area and the number of coil turns of the auxiliary winding
  • the alternating positive and negative pulse signals are input to the auxiliary winding, so that the auxiliary winding is in the preset state, wherein the duty cycle of the pulse signal is the calculated first duty cycle.
  • the method also includes:
  • the leakage current information is obtained according to the re-obtained current signal and the adjusted duty ratio, so as to detect the leakage current of the device under test.
  • the reverse adjustment of the duty ratio of the pulse signal according to the direction information includes:
  • the method also includes:
  • the method further includes:
  • the self-test of the leakage current detection circuit is performed.
  • the leakage current detector includes the leakage current detection circuit described in any of the above embodiments, and/or The leakage current is detected by using the leakage current detection method described in any one of the above embodiments.
  • the embodiment of the present application provides a leakage current detection circuit, a method and a leakage current detector, the leakage current detection circuit includes a main winding, an auxiliary winding, a detection module and a signal output module, and the leakage current detection circuit is used to detect The leakage current of the device is detected, wherein the main winding is used to connect with the leakage current detection terminal of the device under test, the main winding is coupled to the auxiliary winding, and the auxiliary winding is respectively connected to the signal output module connected to the detection module, the signal output module is used to output positive and negative pulse signals alternately, so that the auxiliary winding is in a preset state, at this time, if there is a leakage current on the main winding, it is coupled to the The leakage current of the auxiliary winding is superimposed on the positive and negative alternating pulse signals, so that the current signal detected by the detection module is larger than the current signal detected when the positive and negative alternating pulse signals are not applied, thereby improving the leakage current.
  • FIG. 1 is a schematic structural diagram of a leakage current detection circuit provided in an embodiment of the present application
  • 2a-2c are waveform diagrams of undetected leakage current in a leakage current detection circuit provided by an embodiment of the present application
  • FIG. 3 is a waveform diagram when a leakage current is detected in a leakage current detection circuit provided in an embodiment of the present application
  • FIG. 4 is a schematic diagram of a circuit structure of a leakage current detection circuit provided in an embodiment of the present application.
  • FIG. 5 is a flow chart of a leakage current detection method provided in an embodiment of the present application.
  • 6a-6d are waveform diagrams of current signals corresponding to different duty ratios in the leakage current detection circuit provided by the embodiment of the present application;
  • FIGS. 7a-7c are diagrams for adjusting the measured output value of the auxiliary winding in the leakage current detection circuit provided by the embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a leakage current detection circuit provided by an embodiment of the present application.
  • the leakage current detection circuit 1 is used to detect the leakage current of the device to be tested.
  • the leakage current detection circuit 1 includes a main winding 11, Auxiliary winding 12 , detection module 13 and signal output module 14 .
  • the main winding 11 is used to connect with the leakage current detection terminal of the device under test, the main winding 11 is coupled with the auxiliary winding 12, and the auxiliary winding 12 is respectively connected with the detection module 13 and the signal output Module 14 is connected.
  • the signal output module 14 is used to output positive and negative pulse signals alternately, so that the auxiliary winding 12 is in a preset state;
  • the detection module 13 is used to detect the current signal of the auxiliary winding 12 when the auxiliary winding 12 is in the preset state, and detect the leakage current of the device under test according to the current signal.
  • the main winding 11 is connected to a leakage current detection terminal of the device under test, for example, it may be a leakage current detection terminal of a DC-AC module.
  • the main winding 11 and the auxiliary winding 12 may be inductance components, which are divided into the common mode inductance of the main winding 11 and the auxiliary inductance of the auxiliary winding 12, and the common mode inductance Coupled with the auxiliary inductance, for example, through an iron core, to detect the leakage current of the device under test.
  • the alternating positive and negative pulse signals refer to inputting a positive pulse signal in the first sequence, inputting a negative (reverse) pulse signal in the second sequence, inputting a positive pulse signal in the third sequence, and inputting a positive pulse signal in the fourth sequence.
  • a negative pulse signal is input, which circulates sequentially, and continuously outputs the pulse signal, wherein the direction of the positive pulse signal is opposite to that of the negative pulse signal.
  • the auxiliary winding 12 has a first end and a second end, and The auxiliary winding 12 inputs the positive pulse signal, the positive pulse signal flows in from the first end, and flows out from the second end; the negative pulse signal is input to the auxiliary winding 12, so The negative pulse signal flows in from the second end and flows out from the first end, wherein the positive pulse signal and the negative pulse signal may be electrical signals.
  • the alternating positive and negative pulse signals are output through the signal output module 14 , so that the auxiliary winding 12 is in the preset state.
  • the preset state may refer to the state when the auxiliary winding 12 is in critical saturation, or refers to the magnetic amplification state of the auxiliary winding 12, or refers to when the auxiliary winding 12 is in a state of The state in which the amount of voltage change is the largest when the applied voltage is changed.
  • the signal output module 14 inputs the alternating positive and negative pulse signals to the auxiliary winding 12, and the detection module 13 detects positive and negative alternating current or voltage signals, and the effective value of the positive current is equal to the effective value of the negative current within one cycle.
  • the detection module 13 collects that the effective value of the current within one cycle is zero. That is, when the detection module 13 detects that the current signal is zero, it means that there is no leakage current fault in the device under test.
  • the auxiliary winding 12 when there is a leakage current flowing in the main winding 11, the auxiliary winding 12 will generate a corresponding induced current, and the generated induced current is superimposed with the alternating positive and negative pulse signals, and the detection module 13
  • the detected current information of the auxiliary winding 12 will shift to one side, as shown in Figure 3, when the leakage current is positive, the forward voltage or forward current collected by the detection module 13 will increase , the negative voltage or negative current decreases, and the effective value of the current or voltage detected in one cycle increases, so that the detection of leakage current can be realized, and the sensitivity of leakage current detection can be improved; and there is no need to use high-cost leakage current sensors , reducing the cost of leakage current detection.
  • FIG. 4 is a circuit structure diagram of a leakage current detection circuit provided in an embodiment of the present application.
  • the signal output module 14 includes a first switching tube Q1 , a second switching tube Q2 , a third switching tube Q3 , a fourth switching tube Q4 and a first control unit.
  • the first end of the first switching tube Q1 and the first end of the second switching tube Q2 are used to connect to a power supply, and the second end of the first switching tube Q1 passes through the detection module 13 and the auxiliary winding 12, the second end of the first switching tube Q1 is also connected to the first end of the fourth switching tube Q4, and the second end of the second switching tube Q2 is respectively connected to the auxiliary winding 12 is connected to the first end of the third switching tube Q3, the second end of the third switching tube Q3 and the second end of the fourth switching tube Q4 are used for grounding, and the first The control unit is respectively connected to the control terminals of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4.
  • the first control unit is used to control the on-off states of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4, so as to output the positive Negative alternating pulse signal, wherein the on-off state of the first switching tube Q1 is the same as that of the third switching tube Q3, the on-off state of the second switching tube Q2 is the same as that of the fourth switching tube Q4, And the first switching transistor Q1 and the second switching transistor Q2 are turned on alternately.
  • the first control unit is used to output a PWM signal to control the on-off of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 state; for example, periodically and alternately output the first signal PWM1A and the second signal PWM1B, wherein the first signal PWM1A is used to control the on-off state of the first switch Q1 and the third switch tube Q3, the The second signal PWM1B is used to control the on-off state of the second switching tube Q2 and the fourth switching tube Q4, and the on-off state refers to an on-off state or an off-state. Referring to FIGS.
  • the alternating positive and negative pulse signals include a first signal PWM1A and a second signal PWM1B.
  • the first signal PWM1A corresponds to the positive voltage VCC
  • the second signal PWM1B corresponds to the negative voltage -VCC.
  • the current on the auxiliary winding 12 will be changed by periodically outputting the pulse signal, thereby generating an induced magnetic field
  • the VCC voltage is relatively small, such as 5V or 12V, so the auxiliary The induced electromotive force generated on the winding 12 is also small, and the influence on the main winding 11 can be ignored.
  • the first control unit controls the first switch tube Q1 and the third switch tube Q3 to be turned on
  • the electrical signal output by the power supply passes through the first switch tube Q1 to the The detection module 13, then flows from the detection module 13 to the auxiliary winding 12, and finally flows into the first control unit through the third switch tube Q3.
  • the first control unit controls the second switching tube Q2 and the fourth switching tube Q4 to be turned on
  • the electrical signal output by the power supply is from the power supply to the auxiliary winding 12 through the second switching tube Q2 , and then enter the first control unit from the auxiliary winding 12 through the detection module 13 .
  • alternating positive and negative pulse signals can be input to the auxiliary winding 12 .
  • the detection module 13 includes a sampling resistor R1, an operational amplifier U1 and a second control unit.
  • the first end of the auxiliary winding 12 is connected to the signal output module 14 through the sampling resistor, the two input terminals of the operational amplifier U1 are connected to the two ends of the sampling resistor, and the output terminals of the operational amplifier Connected to the second control unit.
  • the second control unit and the first control unit are the same control module, that is, the CPU in FIG. 4 .
  • the detection module 13 further includes a filter, the first end of the filter is connected to the output end of the operational amplifier U1, and the second end of the filter is connected to the second control unit. .
  • the magnetic core saturation duration of the auxiliary winding 12 is very short, so a filter is provided after the auxiliary winding 12, thereby filtering out the transient caused by the induced current. state spikes to avoid misjudgment by the second control unit.
  • the detection module 13 is further configured to obtain leakage current information according to the current signal and the duty cycle of the pulse signal, and detect the leakage current of the device under test. Specifically, since positive and negative alternating pulse signals are applied to both ends of the auxiliary winding 12, the current signal measured by the detection module 13 is not equal to the actual leakage current signal, and the actual leakage current signal is the same as The duty ratio of the applied pulse signal has a certain proportional relationship, so the leakage current value can be calculated according to the duty ratio and the measured current signal. Further, a functional relational expression between the current signal and the leakage current information is obtained, and the leakage current information is calculated according to the relational expression. The relational expression can be obtained by calculation, or can be obtained by fitting a functional relational expression or a graph through specific experimental data.
  • the detection module 13 is also used to determine whether the current signal is greater than a preset current, and output a leakage current alarm signal when the current signal is greater than the preset current.
  • the detection standard when the actual leakage current value of the device under test is greater than 30mA, it indicates that a leakage fault occurs in the device under test. , then it can be judged by judging whether the measured current signal is greater than the preset current to reduce the calculation load of the processor.
  • the preset current can be customized according to the actual needs of the user; or after the leakage current detection circuit 1 is built, an analog 30mA current signal can be measured on the main winding 11, and the current signal detected at this time can be recorded. And use this current signal as the preset current.
  • the alarm signal may be a signal light, and when the detection module 13 detects that there is a leakage current in the device under test, the signal light becomes bright to generate the alarm signal.
  • the first control unit and the second control unit may be the same CPU, or two CPUs. It only needs to meet the above circuit design requirements.
  • An embodiment of the present application provides a leakage current detection circuit
  • the leakage current detection circuit includes a main winding, an auxiliary winding, a detection module and a signal output module
  • the leakage current detection circuit is used to detect the leakage current of the device under test
  • the main winding is connected to the leakage current detection terminal of the device under test
  • the main winding is coupled to the auxiliary winding
  • the auxiliary winding is respectively connected to the signal output module and the detection module
  • the The signal output module is used to output positive and negative pulse signals alternately, so that the auxiliary winding is in a preset state.
  • the leakage current coupled to the auxiliary winding is consistent with the positive and negative Alternate pulse signals are superimposed, so that the current signal detected by the detection module is larger than the current signal detected when the positive and negative alternating pulse signals are not applied, thereby improving the sensitivity of leakage current detection and eliminating the need to use a more sensitive detection equipment, reducing the cost of testing.
  • FIG. 5 is a flow chart of a leakage current detection method provided in an embodiment of the present application. As shown in FIG. 5, the method is executed by the above leakage current detection circuit, and includes the following steps:
  • the preset state of the auxiliary winding means that the auxiliary winding is in a near-saturation state
  • the near-saturation state means that by periodically outputting positive and negative pulse signals alternately, changing the The direction of the current, so that the auxiliary winding is in a state of near saturation.
  • the pulse signal includes a duty cycle of the pulse signal.
  • the parameter information of the auxiliary winding and the variation of the magnetic induction intensity when the auxiliary winding is in a critical saturation state are acquired, wherein the parameter information includes the magnetic core cross-sectional area and the number of coil turns of the auxiliary winding, and then according to The parameter information and the variation of the magnetic induction intensity are calculated to obtain a first duty cycle of the pulse signal, and at this time, the duty cycle of the pulse signal is the calculated first duty cycle D.
  • the expression for calculating the duty cycle is:
  • Ts is the cycle time
  • Ton is the applied voltage time
  • ⁇ B is the variation of magnetic induction intensity
  • U L is the voltage applied to the auxiliary winding
  • Ton is the time of applying the voltage
  • Ae is the cross-sectional area of the magnetic core
  • Ns is the number of coil turns of the auxiliary winding
  • the f s is the switching frequency
  • the variation of the magnetic induction intensity should be selected according to 1.2-1.5 times of the maximum magnetic induction intensity B max of the magnetic core material. Since the auxiliary winding is applied with alternating positive and negative pulse signals, the auxiliary winding is in a state close to saturation, thereby improving the accuracy of leakage current detection.
  • the leakage current detection circuit can determine the demand for the variation of the magnetic induction intensity, through the relationship between the pulse duty cycle and the magnetic core material and the number of turns of the auxiliary winding coil, the required The magnetic core material and the coil turns of the auxiliary winding meet the requirements, and then the magnetic core material and the coil turns of the auxiliary winding with the best cost performance are selected to reduce circuit design costs.
  • the leakage current detection circuit can determine the demand for the variation of the magnetic induction intensity and the magnetic core material, through the relationship between the duty cycle of the pulse and the number of turns of the auxiliary winding coil, It is determined that the number of coil turns of the auxiliary winding meets the requirements, and then the number of coil turns of the auxiliary winding with the best cost performance is selected, so as to reduce the cost of circuit design.
  • the first duty ratio can also be determined according to the following method:
  • the sensitivity of leakage current detection can be improved by applying a positive and negative pulse signal whose duty cycle is the first duty cycle to the auxiliary winding alternately.
  • the current signal of the auxiliary winding is detected by the detection module, and the current signal includes the direction and magnitude of the current. Specifically, by obtaining the current signal flowing out of the auxiliary winding, the current signal is performing amplification, filtering the amplified current signal, and finally inputting it to the second control unit. Wherein, by amplifying the current signal, the sensitivity of the leakage current detection can be improved, however, the amplified current signal will produce a transient peak, at this time, by filtering the transient peak, it can be Misjudgment by the second control unit is reduced.
  • U L is the voltage on the auxiliary winding
  • the L is the inductance
  • d i is the current increment on the auxiliary winding
  • d t is the time increment on the auxiliary winding.
  • the first control unit changes the direction of the current on the auxiliary winding by controlling the signal output module to periodically output positive and negative pulse signals, so that the voltage on the auxiliary winding Also changed.
  • the signal output module inputs positive and negative alternating pulse signals to the auxiliary winding, and the detection module detects positive and negative alternating current or voltage signals, and within one cycle
  • the effective value of the positive current is equal to the effective value of the negative current, and at this time, the effective value of the current collected by the detection module within one cycle is zero.
  • the generated induced current is superimposed with alternating positive and negative pulse signals, and the current information of the auxiliary winding detected by the detection module will be sent to a side offset, when the leakage current is positive, the positive voltage or positive current collected by the detection module increases, the negative voltage or negative current decreases, and the effective current or voltage is detected within one cycle
  • the value becomes larger, so that the detection of leakage current can be realized, and the sensitivity of leakage current detection can be improved; and there is no need to use a high-cost leakage current sensor, which reduces the cost of leakage current detection.
  • the way of detecting the leakage current of the device under test may be to judge whether the current signal is greater than the preset current, when the current signal is greater than The preset current outputs a leakage current alarm signal.
  • the actual leakage current value of the device under test is greater than 30mA, it indicates that a leakage fault occurs in the device under test. , then it can be judged by judging whether the measured current signal is greater than the preset current to reduce the calculation load of the processor.
  • the preset current can be customized according to the actual needs of the user; it is also possible to measure the simulated 30mA current signal in the main winding after the leakage current detection circuit is built, record the current signal detected at this time, and The current signal is used as the preset current.
  • the method of detecting the leakage current of the device under test according to the current signal may be to obtain leakage current information according to the current signal and the duty cycle of the pulse signal, The leakage current of the device under test is detected. Specifically, since positive and negative alternating pulse signals are applied to both ends of the auxiliary winding, the current signal actually measured by the detection module is not equal to the actual leakage current signal, and the actual leakage current signal is different from the applied pulse signal.
  • the duty cycle of the signal has a certain proportional relationship, so the leakage current value can be calculated according to the duty cycle and the measured current signal. Further, the functional relational expression between the current signal and the leakage current information is obtained, and the leakage current information is calculated according to the relational expression.
  • the relational expression can be obtained by calculation, or can be obtained by fitting the functional relational expression or graph through specific experimental data.
  • the leakage current detection method further includes range extension. Since the transient current peak generated when the auxiliary winding is saturated is easily filtered out, the measurement range will be reduced, so the auxiliary winding measurement output is close to positive and negative balance by reversely adjusting the duty cycle, thereby reducing The influence of magnetic core saturation on the measurement results improves the detection accuracy and realizes the expansion of the measurement range.
  • the direction information of the current signal is obtained, and then the direction information of the pulse signal is reversely adjusted according to the direction information.
  • duty cycle and then re-obtain the current signal of the auxiliary winding, and obtain the leakage current information according to the re-acquired current signal and the adjusted duty cycle, so as to measure the leakage current of the device under test to test.
  • the reverse adjustment of the duty cycle of the pulse signal includes reducing the duty cycle of the positive pulse signal and keeping the duty cycle of the negative pulse signal unchanged when the current signal is detected to be positive. , when it is detected that the current signal is negative, reduce the duty cycle of the negative pulse signal and keep the duty cycle of the positive pulse signal unchanged.
  • the duty cycle of the positive pulse signal PWM1A
  • PWM1B negative pulse information
  • Figures 7a-7c are diagrams for adjusting the measured output value of the auxiliary winding in the leakage current detection circuit provided by the embodiment of the present application, as shown in Figures 7a-7c, when the detected current signal exceeds the preset threshold, and When the current signal is negative, keep the duty cycle of the positive pulse signal (PWM1A) unchanged, and reduce the duty cycle of the negative pulse signal (PWM1B), so that the leakage current and the positive and negative pulse signals alternate, so that the auxiliary winding measurement output is close to Positive and negative balance, thereby reducing the influence of magnetic core saturation on the measurement results, can improve the detection accuracy and realize the expansion of the measurement range.
  • PWM1A positive pulse signal
  • PWM1B negative pulse signal
  • the duty ratio of the pulse signal is reversely adjusted, so that the duty ratio sized for the second duty cycle.
  • the duty ratio of the pulse signal is reversely adjusted, so that the duty ratio sized for the second duty cycle.
  • the first preset threshold is smaller than the second preset threshold
  • the second duty ratio is larger than the third duty ratio, that is, the duty ratios of the current signal and the pulse signal Inversely proportional, when the current signal is larger, the duty cycle of the pulse signal is smaller.
  • the second preset threshold, the third preset threshold, the second duty cycle and the third duty cycle can be designed according to the actual needs of users, or according to the specific
  • the leakage current detection circuit is designed through specific experimental data or simulation results; for example, by simulating various leakage currents on the main winding and adjusting the duty cycle of the pulse signal to obtain multiple sets of experimental data, through Analyzing the experimental data and then setting corresponding values of the second preset threshold, the third preset threshold, the second duty cycle, and the third duty cycle.
  • the above embodiment only lists the second preset threshold and the third preset threshold, and the user can set the fourth preset threshold, the fifth preset threshold, etc. according to actual needs, and then adjust the corresponding duty ratio .
  • the leakage current detection method further includes performing a self-test on the leakage current detection circuit.
  • a current input source is externally connected to the leakage current detection circuit, so that the circuit has a first current, wherein the first current is at least greater than 30 mA.
  • Obtain and record the first output value on the auxiliary winding at this time disconnect the external current input source, so that the first current in the leakage current detection circuit becomes zero, obtain the second output value on the auxiliary winding output value.
  • obtain the duty cycle of the alternating positive and negative pulse signals adjust the duty cycle of one of the pulse signals so that the difference between the first output value and the second output value is within a preset range, and The adjusted duty cycle is obtained, wherein the difference between the second output value and the first output value may be between 0-0.1.
  • the present application provides a leakage current detection method, which is applied to a leakage current detection circuit.
  • the method inputs positive and negative pulse signals alternately to the auxiliary winding to make the auxiliary winding in a preset state, and then When the winding is in the preset state, detect the current signal of the auxiliary winding, and finally detect the leakage current of the device under test according to the current signal, by setting the auxiliary winding in the preset state, so that when the main When there is a leakage current on the winding, the leakage current coupled to the auxiliary winding is superimposed on the alternating positive and negative pulse signals, thereby improving the sensitivity of leakage current detection, and without using a detection device with high sensitivity, reducing the detection cost. cost.
  • An embodiment of the present application also provides a leakage current detector, including any one of the above leakage current detection circuits, and/or adopting any one of the above leakage current detection methods to detect the leakage current, wherein the The leakage current detector changes the direction of the current through the signal output module, thereby increasing the sensitivity of the leakage current detector and reducing the cost of the leakage current detector.

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

漏电流检测电路（1）、方法及漏电流检测器。该漏电流检测电路（1）用于对待测设备的漏电流进行检测，包括主绕组（11）、辅助绕组（12）、检测模块（13）和信号输出模块（14），主绕组（11）与待测设备的漏电流检测端连接，并与辅助绕组（12）耦合，辅助绕组（12）分别与信号输出模块（14）及检测模块（13）连接；信号输出模块（14）用于输出正负交替的脉冲信号，以使辅助绕组（12）处于预设状态，此时若主绕组（11）上有漏电流，耦合到辅助绕组（12）的漏电流与正负交替的脉冲信号叠加，使得检测模块（13）检测到的电流信号较未施加正负交替的脉冲信号时所检测到的电流信号大，从而提高了漏电流检测的灵敏度，并且无需采用灵敏度较高的检测设备，降低了检测的成本。

Description

一种漏电流检测电路、方法及漏电流检测器
相关申请的交叉参考
本申请要求于2021年11月08日提交中国专利局，申请号为202111312286.3，申请名称为“一种漏电流检测电路、方法及漏电流检测器”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及逆变器漏电流检测的技术领域，例如涉及一种漏电流检测电路、方法及漏电流检测器。
背景技术
在光伏或光储并网逆变器中，如果光伏组件阵列各端子与地之间的接触电流大于30mA，则需要功率转换设备(如逆变器)具备残余电流(漏电流)检测或监控保护功能。
现有的技术中，通过电路产生特定频率的方波电压加在电流互感器次边绕组下，当互感器交流输出有不平衡电流(即漏电流)时，将该漏电流感应叠加到次边绕组上，从而被检测电路识别到。通过上述方式检测漏电流，导致在漏电流的检测时出现灵敏度低、成本大的问题。
发明内容
本申请实施例提供了一种漏电流检测电路、方法及漏电流检测器，提高了漏电流检测的灵敏度，并降低了漏电流检测的成本。
为解决上述技术问题，本申请实施例采用的一个技术方案是：提供一种漏电流检测电路，所述漏电流检测电路包括主绕组、辅助绕组、检测模块和信号输出模块；
所述主绕组用于与所述待测设备的漏电流检测端连接，所述主绕组与所述辅助绕组耦合，所述辅助绕组分别与所述信号输出模块及所 述检测模块连接；
所述信号输出模块用于输出正负交替的脉冲信号，以使所述辅助绕组处于预设状态；
所述检测模块用于在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号，根据所述电流信号对所述待测设备的漏电流进行检测。
可选的，所述信号输出模块包括第一开关管、第二开关管、第三开关管、第四开关管和第一控制单元；
所述第一开关管的第一端及所述第二开关管的第一端用于连接电源，所述第一开关管的第二端通过所述检测模块与所述辅助绕组的第一端连接，所述第一开关管的第二端还与所述第四开关管的第一端连接，所述第二开关管的第二端分别与所述辅助绕组的第二端及所述第三开关管的第一端连接，所述第三开关管的第二端及所述第四开关管的第二端用于接地，所述第一控制单元分别与所述第一开关管、所述第二开关管、所述第三开关管及所述第四开关管的控制端连接；
所述第一控制单元用于控制所述第一开关管、所述第二开关管、所述第三开关管及所述第四开关管的通断状态，以输出所述正负交替的脉冲信号，其中，所述第一开关管与所述第三开关管的通断状态相同，所述第二开关管与所述第四开关管的通断状态相同，以及所述第一开关管和所述第二开关管交替导通。
可选的，所述检测模块包括采样电阻、运算放大器及第二控制单元；
所述辅助绕组的第一端通过所述采样电阻与所述信号输出模块连接，所述运算放大器的两个输入端与所述采样电阻的两端连接，所述运算放大器的输出端与所述第二控制单元连接。
可选的，所述检测模块还用于根据所述电流信号及所述脉冲信号的占空比，获取漏电流信息，以对所述待测设备的漏电流进行检测；
或者，所述检测模块还用于判断所述电流信号是否大于预设电流，当所述电流信号大于所述预设电流，输出漏电流报警信号。
为解决上述技术问题，本申请实施例采用的另一个技术方案是： 提供一种漏电流检测方法，应用于上述任一实施例中的漏电流检测电路，所述方法包括：向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态；
在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号；
根据所述电流信号，对所述待测设备的漏电流进行检测。
可选的，所述向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态包括：
获取所述辅助绕组的参数信息，其中，所述参数信息包括所述辅助绕组的磁芯截面积、线圈匝数；
获取所述辅助绕组处于临界饱和状态时的磁感应强度变化量；
根据所述参数信息及所述磁感应强度变化量，计算得到所述脉冲信号的第一占空比；
向所述辅助绕组输入所述正负交替的脉冲信号，以使所述辅助绕组处于所述预设状态，其中所述脉冲信号的占空比大小为计算得到的所述第一占空比。
可选的，所述方法还包括：
检测所述电流信号是否大于预设阈值；
当所述电流信号大于所述预设阈值时，获取所述电流信号的方向信息；
根据所述方向信息，反向调节所述脉冲信号的占空比大小，重新获得所述辅助绕组的电流信号；
根据重新获得的所述电流信号及调节后的占空比大小，获得所述漏电流信息，以对所述待测设备的漏电流进行检测。
可选的，所述根据所述方向信息，反向调节所述脉冲信号的占空比大小，包括：
当检测到所述电流信号为正时，减小正向脉冲信号的占空比，保持负向脉冲信号的占空比不变；
当检测到所述电流信号为负时，减小负向脉冲信号的占空比，保持正脉冲信号的占空比不变。
可选的，所述的方法还包括：
当检测所述电流信号大于第一预设阈值且小于第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第二占空比；
当检测到所述电流信号大于所述第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第三占空比；其中，所述第一预设阈值小于所述第二预设阈值，所述第二占空比大于所述第三占空比。
可选的，所述向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态之后还包括：
调整所述正负交替的脉冲信号中正向或负向占空比大小，以使得正向脉冲信号与负向脉冲信号的占空比大小相异，并实时检测所述辅助绕组的电流信号；
通过判断所述电流信号的大小，对所述漏电流检测电路的自检。
为解决上述技术问题，本申请实施例采用的又一个技术方案是：提供一种漏电流检测器，所述漏电流检测器包括上述任一实施例中所述的漏电流检测电路，和/或，采用上述任一实施例所述的漏电流检测方法对漏电流进行检测。
本申请实施例提供了一种漏电流检测电路、方法及漏电流检测器，所述漏电流检测电路包括主绕组、辅助绕组、检测模块和信号输出模块，所述漏电流检测电路用于对待测设备的漏电流进行检测，其中，所述主绕组用于与所述待测设备的漏电流检测端连接，所述主绕组与所述辅助绕组耦合，所述辅助绕组分别与所述信号输出模块及所述检测模块连接，所述信号输出模块用于输出正负交替的脉冲信号，以使所述辅助绕组处于预设状态，此时，若所述主绕组上有漏电流，耦合到所述辅助绕组的漏电流与所述正负交替的脉冲信号叠加，使得所述检测模块所检测到的电流信号较未施加所述正负交替脉冲信号时所检测到的电流信号大，从而提高了漏电流检测的灵敏度，并且无需采用灵敏度较高的检测设备，降低了检测的成本。
附图说明
一个或多个实施例通过与之对应的附图进行示例性说明，这些示例性说明并不构成对实施例的限定，附图中具有相同参考数字标号的元件表示为类似的元件，除非有特别申明，附图中的图不构成比例限制。
图1是本申请实施例提供的一种漏电流检测电路的结构示意图；
图2a-2c是本申请实施例提供的一种漏电流检测电路中的未检测到漏电流的波形图；
图3是是本申请实施例提供的一种漏电流检测电路中检测出漏电流时的波形图；
图4是本申请实施例提供的一种漏电流检测电路的电路结构示意图；
图5是本申请实施例提供的一种漏电流检测方法的流程图；
图6a-6d是本申请实施例提供的漏电流检测电路中不同占空比对应的电流信号的波形图；
图7a-7c是本申请实施例提供的漏电流检测电路中辅助绕组测量输出值调整图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本申请，并不用于限定本申请。
需要说明的是，如果不冲突，本申请实施例中的各个特征可以相互组合，均在本申请的保护范围之内。另外，虽然在装置示意图中进行了功能模块的划分，在流程图中示出了逻辑顺序，但是在某些情况下，可以以不同于装置示意图中的模块划分，或流程图中的顺序执行所示出或描述的步骤。
除非另有定义，本说明书所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。在本申请的说明书中所使用的术语只是为了描述具体的实施方式的目的，不是用于限 制本申请。本说明书所使用的术语“和/或”包括一个或多个相关的所列项目的任意的和所有的组合。
请参阅图1，图1是本申请实施例提供的漏电流检测电路的结构示意图，漏电流检测电路1用于对待测设备的漏电流进行检测，所述漏电流检测电路1包括主绕组11、辅助绕组12、检测模块13和信号输出模块14。
其中，所述主绕组11用于与所述待测设备的漏电流检测端连接，所述主绕组11与所述辅助绕组12耦合，所述辅助绕组12分别与所述检测模块13及信号输出模块14连接。
所述信号输出模块14用于输出正负交替的脉冲信号，以使所述辅助绕组12处于预设状态；
所述检测模块13用于在所述辅助绕组12处于所述预设状态时，检测所述辅助绕组12的电流信号，根据所述电流信号对所述待测设备的漏电流进行检测。
具体的，所述主绕组11连接在所述待测设备的漏电流检测端，例如可以是DC-AC模块的漏电流检测端。在一些实施例中，所述主绕组11和所述辅助绕组12可以是电感元器件，分为所述主绕组11的共模电感和所述辅助绕组12的辅助电感，将所述共模电感和所述辅助电感耦合，例如通过铁芯耦合，以检测所述待测设备的漏电流。
具体的，所述正负交替的脉冲信号是指在第一时序中输入正向脉冲信号，第二个时序中输入负(反)向脉冲信号，第三时序中输入正向脉冲信号，第四时序中输入负向脉冲信号，依次循环，持续输出脉冲信号，其中所述正向脉冲信号与所述负向脉冲信号方向相对，例如，所述辅助绕组12具有第一端与第二端，向所述辅助绕组12输入所述正向脉冲信号，所述正向脉冲信号从所述第一端流入，从所述第二端流出；向所述辅助绕组12输入所述负向脉冲信号，所述负向脉冲信号从所述第二端流入，从所述第一端流出，其中，所述正向脉冲信号和所述负向脉冲信号可以是电信号。如此通过所述信号输出模块14输出所述正负交替的脉冲信号，使得所述辅助绕组12处于所述预设状态。需说明的是，所述预设状态可以是指所述辅助绕组12处于临 界饱和时的状态，或者，是指所述辅助绕组12处于磁放大状态，亦或者是指当所述辅助绕组12所施加电压发生改变时，电压变化量最大的状态。
具体的，如图2a-2c所示，当所述主绕组11上没有产生漏电流时，所述信号输出模块14向所述辅助绕组12输入所述正负交替的脉冲信号，所述检测模块13检测到正负交替的电流或电压信号，且在一个周期内正向电流的有效值与负向电流有效值相等，此时所述检测模块13采集到一个周期内的电流有效值为零。即当所述检测模块13检测到所述电流信号为零时，说明所述待测设备未出现漏电流故障。
而当所述主绕组11中有漏电流流过时，所述辅助绕组12会产生相应的感应电流，所产生的所述感应电流与所述正负交替的脉冲信号叠加，所述检测模块13所检测到的所述辅助绕组12的电流信息会向一侧偏移，如图3所述，当漏电流为正时，则所述检测模块13所采集到的正向电压或正向电流增大，负向电压或负向电流减小，一个周期内检测到电流或电压的有效值变大，从而可以实现漏电流的检测，以及提升漏电流检测的灵敏度；并且无需采用高成本的漏电流传感器，降低了漏电流检测的成本。
在一些实施例中，请参阅图4，图4是本申请实施例提供的一种漏电流检测电路的电路结构图。
如图4所示，所述信号输出模块14包括第一开关管Q1、第二开关管Q2、第三开关管Q3、第四开关管Q4和第一控制单元。所述第一开关管Q1的第一端及所述第二开关管Q2的第一端用于连接电源，所述第一开关管Q1的第二端通过所述检测模块13与所述辅助绕组12的第一端连接，所述第一开关管Q1的第二端还与所述第四开关管Q4的第一端连接，所述第二开关管Q2的第二端分别与所述辅助绕组12的第二端及所述第三开关管Q3的第一端连接，所述第三开关管Q3的第二端及所述第四开关管Q4的第二端用于接地，所述第一控制单元分别与所述第一开关管Q1、所述第二开关管Q2、所述第三开关管Q3及所述第四开关管Q4的控制端连接。
所述第一控制单元用于控制所述第一开关管Q1、所述第二开关 管Q2、所述第三开关管Q3及所述第四开关管Q4的通断状态，以输出所述正负交替的脉冲信号，其中，所述第一开关管Q1与所述第三开关管Q3的通断状态相同，所述第二开关管Q2与所述第四开关管Q4的通断状态相同，以及所述第一开关管Q1及所述第二开关管Q2交替导通。
其中，所述第一控制单元用于输出PWM信号，以控制所述第一开关管Q1、所述第二开关管Q2、所述第三开关管Q3及所述第四开关管Q4的通断状态；例如，周期性的交替输出第一信号PWM1A和第二信号PWM1B，其中所述第一信号PWM1A用于控制所述第一开关Q1及所述第三开关管Q3的通断状态，所述第二信号PWM1B用于控制所述第二开关管Q2及所述第四开关管Q4的通断状态，所述通断状态是指导通或者断开状态。请参阅图2a-2b，所述正负交替的脉冲信号包括第一信号PWM1A和第二信号PWM1B。所述第一信号PWM1A对应正电压VCC，所述第二信号PWM1B对应负电压-VCC，通过周期性的输出所述正负交替的脉冲信号，使得所述辅助绕组12上流经不同方向的电流，以使所述辅助绕组12处于临界饱和状态。
需要说明的是，虽然通过周期性的输出所述脉冲信号会使所述辅助绕组12上的电流发生改变，从而产生感应磁场，但一般VCC电压相对较小，例如5V或12V，所以所述辅助绕组12上产生的感应电动势也较小，对所述主绕组11的影响可以忽略不计。
具体的，当所述第一控制单元控制所述第一开关管Q1和所述第三开关管Q3导通时，电源输出的电信号从所述电源经过所述第一开关管Q1到所述检测模块13，然后从所述检测模块13到所述辅助绕组12，最后再通过所述第三开关管Q3流进所述第一控制单元。当所述第一控制单元控制所述第二开关管Q2和所述第四开关管Q4导通时，电源输出的电信号从所述电源经所述第二开关管Q2到所述辅助绕组12上，然后从所述辅助绕组12经所述检测模块13进入所述第一控制单元。如此，通过交替控制所述第一开关管Q1与第二开关管Q2的导通状态，可以向所述辅助绕组12输入正负交替的脉冲信号。
如图4所示，在一些实施例中，所述检测模块13包括采样电阻 R1、运算放大器U1及第二控制单元。所述辅助绕组12的第一端通过所述采样电阻与所述信号输出模块14连接，所述运算放大器U1的两个输入端与所述采样电阻的两端连接，所述运算放大器的输出端与所述第二控制单元连接。本实施例中，所述第二控制单元与所述第一控制单元为同一控制模块，即图4中的CPU。
在一些实施例，所述检测模块13还包括滤波器，所述滤波器的第一端与所述运算放大器U1的输出端连接，所述滤波器的第二端与所述第二控制单元连。
具体的，由于所述电流方向不断发生改变，使得所述辅助绕组12的磁芯饱和持续时间很短，所以在所述辅助绕组12后设置一个滤波器，从而滤除所述感应电流产生的瞬态尖峰，以避免所述第二控制单元产生误判。
在一些实施例中，所述检测模块13还用于根据所述电流信号及所述脉冲信号的占空比，以获取漏电流信息，对所述待测设备的漏电流进行检测。具体的，由于所述辅助绕组12两端施加了正负交替的脉冲信号，则所述检测模块13所测得的所述电流信号不等于实际的漏电流信号，所述实际的漏电流信号与所施加脉冲信号的占空比成一定比例关系，因此可以根据占空比大小与所测得的电流信号计算漏电流值。进一步地，获取所述电流信号与所述漏电流信息的函数关系式，根据关系式计算得到漏电流信息，该关系式可以计算获得，也可以通过具体实验数据拟合函数关系式或者曲线图。
在一些实施例中，所述检测模块13还用于判断所述电流信号是否大于预设电流，当所述电流信号大于所述预设电流，输出漏电流报警信号。具体的，根据检测标准，当所述待测设备的实际漏电流值大于30mA时，则说明所述待测设备出现漏电故障，因此，可以根据用户的需求，若仅需判断是否出现漏电流故障，那么可以通过判断所测得电流信号是否大于预设电流的方式进行判断，降低处理器计算负荷。进一步地，该预设电流可以根据用户实际需求进行自定义；也可以在漏电流检测电路1搭建完成后，在所述主绕组11测模拟30mA的电流信号，记录此时检测到的电流信号，并将该电流信号作为预设电流。
具体的，所述报警信号可以是信号灯，当所述检测模块13检测到所述待测设备中有漏电流时，所述信号灯变亮，以产生所述报警信号。
其中，所述第一控制单元和所述第二控制单元可以是同一个CPU，也可以是两个CPU。其只需满足上述电路设计要求即可。
本申请实施例提供了一种漏电流检测电路，所述漏电流检测电路包括主绕组、辅助绕组、检测模块和信号输出模块，所述漏电流检测电路用于对待测设备的漏电流进行检测，其中，所述主绕组与所述待测设备的漏电流检测端连接，所述主绕组与所述辅助绕组耦合，所述辅助绕组分别与所述信号输出模块及所述检测模块连接，所述信号输出模块用于输出正负交替的脉冲信号，以使所述辅助绕组处于预设状态，当所述主绕组上有漏电流时，耦合到所述辅助绕组上的漏电流与所述正负交替的脉冲信号叠加，使得所述检测模块所检测到的电流信号较未施加正负交替脉冲信号时所检测到的电流信号大，从而提高了漏电流检测的灵敏度，无需采用灵敏度较高的检测设备，降低了检测的成本。
请参阅图5，所述图5是本申请实施例提供的一种漏电流检测方法的流程图，如图5所示，所述方法由上述漏电流检测电路执行，包括如下步骤：
S01、向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态。
其中，所述辅助绕组的预设状态指的是使所述辅助绕组处于临近饱和状态，而所述临近饱和状态指的是通过周期性的输出正负交替的脉冲信号，改变所述辅助绕组中的电流方向，从而使得所述辅助绕组处于临近饱和状态。
所述脉冲信号包括脉冲信号的占空比。具体的，获取所述辅助绕组的参数信息和所述辅助绕组处于临界饱和状态时的磁感应强度变化量，其中，所述参数信息包括所述辅助绕组的磁芯截面积、线圈匝数，然后根据所述参数信息及所述磁感应强度变化量，计算得到所述脉冲信号的第一占空比，此时，所述脉冲信号的占空比大小为计算得 到的所述第一占空比D。
具体的，所述计算占空比的表达式为：
Figure PCTCN2022081474-appb-000001
其中，Ts为周期时间，Ton为所加电压时间；
所述加电压时间的表达式为：
Figure PCTCN2022081474-appb-000002
其中，△B为磁感应强度变化量，U L为加在辅助绕组上的电压，Ton为所加电压的时间，Ae为磁芯截面积，Ns为辅助绕组的线圈匝数；
所述周期时间的表达式为：
Figure PCTCN2022081474-appb-000003
其中，所述f s为开关频率。
需要说明的是，所述磁感应强度变化量应根据磁芯材料的最大磁感应强度B max的1.2-1.5倍进行选择。由于对所述辅助绕组施加正负交替的脉冲信号，使得所述辅助绕组处于临近饱和状态，从而提升漏电流检测的准确度。
以下是一具体第一占空比计算过程，磁芯的最大饱和磁感应强度B max为0.36T，辅助绕组处于临界饱和状态的磁感应强度变化量△B取最大饱和磁感应强度B max的1.2倍，则△B＝0.432T；磁芯截面积Ae＝0.0596cm 2，开关频率fs取7KHz，辅助绕组的匝数N为73，所述脉冲信号的峰值电压VCC＝5V，即UL＝5V；将上述数据带入式(1)、式(2)及式(3)，计算所得到的占空比D为0.263。即控制信号输 出模块输出占空比为0.263的脉冲信号，即可以使所述辅助绕组处于预设状态，即临界饱和状态。
在一些实施例中，所述漏电流检测电路在可以确定磁感应强度变化量的需求前提下，通过脉冲的占空比与所述磁芯材料和所述辅助绕组线圈匝数的关系，确定需要的所述磁芯材料与所述辅助绕组线圈匝数满足要求，进而选定性价比最佳的所述磁芯材料与所述辅助绕组的线圈匝数，以降低电路设计成本。
在另一实施例中，所述漏电流检测电路在可以确定所述磁感应强度变化量的需求及所述磁芯材料前提下，通过脉冲的占空比与所述辅助绕组线圈匝数的关系，确定所述辅助绕组线圈匝数满足要求，进而选定性价比最佳的所述辅助绕组的线圈匝数，以降低电路设计成本。
在一个实施例中，所述第一占空比还可以根据以下方法确定：
向所述辅助绕组输入多个相异占空比的正向或负向脉冲信号；
检测各占空比所对应的电流信号；
根据各占空比及所对应的电流信号，拟合占空比与电流信号的曲线；
获取所拟合的占空比与电流信号的曲线中斜率最大点所对应的占空比大小，并将该占空比大小设置为第一占空比；
向所述辅助绕组输入占空比大小为第一占空比的正负交替的脉冲信号，以使所述辅助绕组处于所述预设状态。
具体的，通过向所述辅助绕组输入多个相异占空比的正向或负向脉冲信号，并通过所述检测模块读取所述辅助绕组在不同占空比所对应的电流信息，从而可以获取占空比与电流信息对应关系的多个离散点，所获取的离散点越多，所拟合的占空比与电流信息的曲线越接近实际检测值，对所述漏电流的检测也就越准确。如图6a-6d所示，在所述辅助绕组输入不同占空比时，所对应的电流信号的有效值也不同(以单向脉冲信号为例)，一般的，随着脉冲信号的不断增大，对应电流信号的变化量会慢慢变大，然后慢慢减小。因此通过获取所拟合的占空比与电流信号的曲线中斜率最大点所对应的占空比大小，即获取当占空比发生改变，电流信号变化量最大的点。也即，当所述主绕 组产生漏电流时，所检测到的电流信号值越大，漏电流检测灵敏度越大。如此，通过向所述辅助绕组施加占空比大小为第一占空比的正负交替的脉冲信号，可以提升漏电流检测的灵敏度。
S02、在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号。
其中，通过所述检测模块检测所述辅助绕组的电流信号，所述电流信号包括所述电流的方向及大小，具体的，通过获取所述辅助绕组上流出的电流信号，然后将所述电流信号进行放大，并将所述放大后的电流信号进行滤波，最后输入到所述第二控制单元。其中，通过将所述电流信号进行放大，从而可以提高所述漏电流检测的灵敏度，然而，所述放大后的电流信号会产生瞬间尖峰，此时，通过将所述瞬间尖峰滤除掉，可以减少所述第二控制单元产生误判。
具体的，当所述辅助绕组处于所述预设状态时，若所述主绕组上存在漏电流，则所述辅助绕组上也会产生相应的感应电流，导致所述辅助绕组上电流会正向或反向的增加，根据公式可得知：
Figure PCTCN2022081474-appb-000004
其中，U L是所述辅助绕组上的电压，所述L是电感量，d i是所述辅助绕组上的电流增量，d t是所述辅助绕组上的时间增量。
当所述辅助绕组上产生感应电流时，所述辅助绕组上的电流会急剧变大，所述辅助绕组上的输出电压也会变大，最终被所述检测模块检测到，从而确定所述待测设备上存在漏电流并发出报警信号。
S03、根据所述电流信号，对待测设备的漏电流进行检测。
具体的，请参阅图2c，所述第一控制单元通过控制所述信号输出模块周期性的输出正负交替的脉冲信号，改变所述辅助绕组上的电流方向，使得所述辅助绕组上的电压也发生改变。当所述主绕组上没有产生漏电流时，所述信号输出模块向所述辅助绕组输入正负交替的脉冲信号，所述检测模块检测到正负交替的电流或电压信号，且在一个周期内正向电流的有效值与负向电流有效值相等，此时检测模块采 集到一个周期内的电流有效值为零。
请参阅图3，当所述漏电流检测电路中存在漏电流时，所产生的感应电流与正负交替的脉冲信号叠加，所述检测模块所检测到的所述辅助绕组的电流信息会向一侧偏移，当漏电流为正时，则所述检测模块所采集到的正向电压或正向电流增大，负向电压或负向电流减小，一个周期内检测到电流或电压的有效值变大，从而可以实现漏电流的检测，以及提升漏电流检测的灵敏度；并且无需采用高成本的漏电流传感器，降低漏电流检测成本。
具体的，在一实施例中，根据所述电流信号，对所述待测设备的漏电流进行检测的方式可以是，判断所述电流信号是否大于所述预设电流，当所述电流信号大于所述预设电流，输出漏电流报警信号。具体的，根据一些标准，当所述待测设备的实际漏电流值大于30mA时，则说明所述待测设备出现漏电故障，因此，可以根据用户的需求，若仅需判断是否出现漏电流故障，那么可以通过判断所测得电流信号是否大于预设电流的方式进行判断，降低处理器计算负荷。进一步地，该预设电流可以根据用户实际需求进行自定义；也可以在漏电流检测电路搭建完成后，在所述主绕组测量模拟30mA的电流信号，记录此时检测到的电流信号，将该电流信号作为预设电流。在另一实施例中，根据所述电流信号，对所述待测设备的漏电流进行检测的方式可以是，根据所述电流信号及所述脉冲信号的占空比，以获取漏电流信息，对所述待测设备的漏电流进行检测。具体的，由于所述辅助绕组两端施加了正负交替的脉冲信号，则所述检测模块实际所测得的电流信号不等于实际的漏电流信号，所述实际的漏电流信号与所施加脉冲信号的占空比成一定比例关系，因此可以根据占空比大小与所测得的电流信号计算漏电流值。进一步地，获取电流信号与漏电流信息的函数关系式，根据关系式计算得到漏电流信息，该关系式可以计算获得，也可以通过具体实验数据拟合函数关系式或者曲线图。
在一些实施例中，所述漏电流检测方法还包括量程扩展。由于所述辅助绕组饱和时产生的瞬态电流尖峰容易被滤除掉，所以会导致测量的量程变小，所以通过反向调节占空比使所述辅助绕组测量输出接 近正负平衡，从而减少磁芯饱和对测量结果的影响，提高检测精度并实现测量量程的扩展。
具体的，首先判断所述电流信号是否大于预设阈值，当所述电流信号大于预设阈值时，获取所述电流信号的方向信息，然后根据所述方向信息，反向调节所述脉冲信号的占空比大小，接着重新获得所述辅助绕组的电流信号，根据重新获得的所述电流信号及调节后的占空比大小，获得所述漏电流信息，以对所述待测设备的漏电流进行检测。通过上述方式，可以减少磁芯饱和对测量结果的影响的同时，可以提高检测精度并实现测量量程的扩展。
其中，所述反向调节所述脉冲信号的占空比大小包括当检测到所述电流信号为正时，减小正向脉冲信号的占空比，保持负向脉冲信号的占空比不变，当检测到所述电流信号为负时，减小负向脉冲信号的占空比，保持正脉冲信号的占空比不变。如图2a-2c所示，当向所述辅助绕组输入正负交替的脉冲信号且所检测的电流信息未超过预设值时，正向脉冲信号(PWM1A)的占空比与负向脉冲信息(PWM1B)占空比大小相等或接近相等。
请参阅图7a-7c，图7a-7c是本申请实施例提供的漏电流检测电路中辅助绕组测量输出值调整图，如图7a-7c所示，当检测到电流信号超过预设阈值，且电流信号为负时，保持正向脉冲信号(PWM1A)占空比不变，减小负向脉冲信号(PWM1B)占空比，使得漏电流与正负交替的脉冲信号，使辅助绕组测量输出接近正负平衡，从而减少磁芯饱和对测量结果的影响，可以提高检测精度并实现测量量程的扩展。
具体的，当检测所述电流信号大于第一预设阈值且小于第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第二占空比。当检测到所述电流信号大于所述第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第三占空比。其中，所述第一预设阈值小于所述第二预设阈值，所述第二占空比大于所述第三占空比，也即，所述电流信号和所述脉冲信号的占空比成反比例关系， 当所述电流信号越大时，所述脉冲信号的占空比越小。应当理解的是，所述第二预设阈值、所述第三预设阈值、所述第二占空比及所述第三占空比可以根据用户实际需求进行设计，或者根据所搭建的具体漏电流检测电路，通过具体实验数据或模拟仿真的结果进行设计；例如，通过在所述主绕组上模拟输入各种漏电流，并调节脉冲信号的占空比，以获得多组实验数据，通过分析实验数据进而设置所述第二预设阈值、所述第三预设阈值、所述第二占空比及所述第三占空比的对应数值。即本领域技术人员在获知本申请所提供的技术方案后，通过有限次实验获得上述数值的确定；也就是说，所述第二预设阈值、所述第三预设阈值、所述第二占空比及所述第三占空比的具体设置数值非本申请重点。另外对应的实际漏电流的计算，亦可以通过查找具体的实验数据所获取对应表或对应关系获得。
需说明的是，上述实施例仅列举了第二预设阈值、第三预设阈值，用户可以根据实际需求设置第四预设阈值，第五预设阈值等，进而调整对应的占空比大小。
在一些实施例中，所述漏电流检测方法还包括对所述漏电流检测电路进行自检。
具体的，调整所述正负交替的脉冲信号中正向或负向占空比大小，以使得正向脉冲信号与所述负向脉冲信号的占空比大小相异，并实时检测所述辅助绕组的电流信号，然后通过判断所述电流信号的大小，以实现对所述漏电流检测电路的自检。
具体的，在所述漏电流检测电路上外接电流输入源，使得所述电路上有第一电流，其中，所述第一电流至少大于30毫安。获取并记录此时所述辅助绕组上的第一输出值，断开所述外接电流输入源，使得所述漏电流检测电路中的第一电流变为零，获取所述辅助绕组上的第二输出值。然后获取所述正负交替的脉冲信号的占空比，调整其中一脉冲信号的占空比，以使所述第一输出值与所述第二输出值的差值在预设范围内，并获取调整后的占空比，其中，所述第二输出值与所述第一输出值之间的差值可以是在0-0.1之间。最后，将调整后的占空比和另一脉冲信号的占空比设置为自检初始脉冲宽度。在主绕组漏 电流为零时，减小第一信号PWM1A或第二信号PWM1B的脉冲宽度，使得磁芯正负励磁不相等，从而在所述辅助绕组里人为产生正负不平衡电流，主动触发漏电流故障实现设备自检。
本申请提供一种漏电流检测方法，应用于漏电流检测电路，所述方法通过向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态，然后在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号，最后根据所述电流信号，对待测设备的漏电流进行检测，通过将所述辅助绕组处于预设状态，使得当所述主绕组上有漏电流时，耦合到所述辅助绕组的漏电流与所述正负交替的脉冲信号叠加，从而提高了漏电流检测的灵敏度，并且无需采用灵敏度较高的检测设备，降低了检测的成本。
需要说明的是，在上述各个实施例中，上述各步骤之间并不必然存在一定的先后顺序，本领域普通技术人员，根据本申请实施例的描述可以理解，不同实施例中，上述各步骤可以有不同的执行顺序，亦即，可以并行执行，亦可以交换执行等等。
本申请实施例还提供一种漏电流检测器，包括上述任一项的漏电流检测电路，和/或，采用上述任一项所述的漏电流检测方法对漏电流进行检测，其中，所述漏电流检测器通过信号输出模块改变电流的方向，从而增加了所述漏电流检测器的灵敏度，降低了漏电流检测器的成本。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；在本申请的思路下，以上实施例或者不同实施例中的技术特征之间也可以进行组合，步骤可以以任意顺序实现，并存在如上所述的本申请的不同方面的许多其它变化，为了简明，它们没有在细节中提供；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (11)

  1. 一种漏电流检测电路，用于对待测设备的漏电流进行检测，其特征在于，所述漏电流检测电路包括主绕组、辅助绕组、检测模块和信号输出模块；
    所述主绕组用于与所述待测设备的漏电流检测端连接，所述主绕组与所述辅助绕组耦合，所述辅助绕组分别与所述信号输出模块及所述检测模块连接；
    所述信号输出模块用于输出正负交替的脉冲信号，以使所述辅助绕组处于预设状态；
    所述检测模块用于在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号，根据所述电流信号对所述待测设备的漏电流进行检测。
  2. 根据权利要求1所述的漏电流检测电路，其特征在于，所述信号输出模块包括第一开关管、第二开关管、第三开关管、第四开关管和第一控制单元；
    所述第一开关管的第一端及所述第二开关管的第一端用于连接电源，所述第一开关管的第二端通过所述检测模块与所述辅助绕组的第一端连接，所述第一开关管的第二端还与所述第四开关管的第一端连接，所述第二开关管的第二端分别与所述辅助绕组的第二端及所述第三开关管的第一端连接，所述第三开关管的第二端及所述第四开关管的第二端用于接地，所述第一控制单元分别与所述第一开关管、所述第二开关管、所述第三开关管及所述第四开关管的控制端连接；
    所述第一控制单元用于控制所述第一开关管、所述第二开关管、所述第三开关管及所述第四开关管的通断状态，以输出所述正负交替的脉冲信号，其中，所述第一开关管与所述第三开关管的通断状态相同，所述第二开关管与所述第四开关管的通断状态相同，以及所述第一开关管和所述第二开关管交替导通。
  3. 根据权利要求1或2所述的漏电流检测电路，其特征在于，所述检测模块包括采样电阻、运算放大器及第二控制单元；
    所述辅助绕组的第一端通过所述采样电阻与所述信号输出模块 连接，所述运算放大器的两个输入端与所述采样电阻的两端连接，所述运算放大器的输出端与所述第二控制单元连接。
  4. 根据权利要求1所述的漏电流检测电路，其特征在于，所述检测模块还用于根据所述电流信号及所述脉冲信号的占空比，获取漏电流信息，以对所述待测设备的漏电流进行检测；
    或者，所述检测模块还用于判断所述电流信号是否大于预设电流，当所述电流信号大于所述预设电流，输出漏电流报警信号。
  5. 一种漏电流检测方法，应用于权利要求1至4任一项中所述的漏电流检测电路，其特征在于，包括：
    向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态；
    在所述辅助绕组处于所述预设状态时，检测所述辅助绕组的电流信号；
    根据所述电流信号，对所述待测设备的漏电流进行检测。
  6. 根据权利要求5所述的漏电流检测方法，其特征在于，所述向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态包括：
    获取所述辅助绕组的参数信息，其中，所述参数信息包括所述辅助绕组的磁芯截面积、线圈匝数；
    获取所述辅助绕组处于临界饱和状态时的磁感应强度变化量；
    根据所述参数信息及所述磁感应强度变化量，计算得到所述脉冲信号的第一占空比；
    向所述辅助绕组输入所述正负交替的脉冲信号，以使所述辅助绕组处于所述预设状态，其中所述脉冲信号的占空比大小为计算得到的所述第一占空比。
  7. 根据权利要求5或6所述的漏电流检测方法，其特征在于，所述方法还包括：
    检测所述电流信号是否大于预设阈值；
    当所述电流信号大于所述预设阈值时，获取所述电流信号的方向信息；
    根据所述方向信息，反向调节所述脉冲信号的占空比大小，重新获得所述辅助绕组的电流信号；
    根据重新获得的所述电流信号及调节后的占空比大小，获得所述漏电流信息，以对所述待测设备的漏电流进行检测。
  8. 根据权利要求7所述的漏电流检测方法，其特征在于，所述根据所述方向信息，反向调节所述脉冲信号的占空比大小，包括：
    当检测到所述电流信号为正时，减小正向脉冲信号的占空比，保持负向脉冲信号的占空比不变；
    当检测到所述电流信号为负时，减小负向脉冲信号的占空比，保持正脉冲信号的占空比不变。
  9. 根据权利要求7所述的漏电流检测方法，其特征在于，所述的方法还包括：
    当检测所述电流信号大于第一预设阈值且小于第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第二占空比；
    当检测到所述电流信号大于所述第二预设阈值时，根据所述方向信息，反向调节所述脉冲信号的占空比大小，以将所述占空比大小调节为第三占空比；其中，所述第一预设阈值小于所述第二预设阈值，所述第二占空比大于所述第三占空比。
  10. 根据权利要求5所述的漏电流检测方法，其特征在于，所述向所述辅助绕组输入正负交替的脉冲信号，以使所述辅助绕组处于预设状态之后还包括：
    调整所述正负交替的脉冲信号中正向或负向占空比大小，以使得正向脉冲信号与负向脉冲信号的占空比大小相异，并实时检测所述辅助绕组的电流信号；
    通过判断所述电流信号的大小，对所述漏电流检测电路的自检。
  11. 一种漏电流检测器，其特征在于，所述漏电流检测器包括如权利要求1-4任一项所述的漏电流检测电路，和/或，采用如权利要求5-10任一项所述的漏电流检测方法对漏电流进行检测。
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