CN105548719A - Detection circuit and method of grounding insulation resistors - Google Patents
Detection circuit and method of grounding insulation resistors Download PDFInfo
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- CN105548719A CN105548719A CN201511017354.8A CN201511017354A CN105548719A CN 105548719 A CN105548719 A CN 105548719A CN 201511017354 A CN201511017354 A CN 201511017354A CN 105548719 A CN105548719 A CN 105548719A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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Abstract
The invention provides a detection circuit and method of grounding insulation resistors. The detection circuit comprises a positive input end, a negative input end, a first resistor, a second resistor, a third resistor, a fourth resistor, a first switch, a sampling conditioning circuit module and a processor. The sampling conditioning circuit module is used for acquiring voltages of the input ends and outputting multiple first voltages with different voltage values when the first switch is switched off and acquiring voltages of the input ends and outputting multiple second voltages with different voltage values when the first switch is switched on; and the processor is used for selecting first voltages for calculation from the multiple first voltages with the different voltage values, selecting second voltages for calculation from the multiple second voltages with the different voltage values, and according to the first voltages and the second voltages, calculating resistance of a grounding insulation resistor of a positive output end of a device to be detected and a grounding insulation resistor of a negative output end of the device to be detected so as to reduce errors of calculated grounding insulation resistance.
Description
Technical field
The present invention relates to technical field of photovoltaic power generation, more particularly, relate to a kind of testing circuit and method of insulation against ground resistance.
Background technology
Grid-connected photovoltaic system is and the system of line voltage with the alternating current of frequency homophase, and it can power to the load, again can to electrical network transmission of electric energy.
In the process of parallel network power generation, if the resistance of the insulation against ground resistance of photovoltaic array lower than certain index request or Ohmic contact bad, with regard to the personal safety of entail dangers to photovoltaic power generation equipment or user.Therefore, need to detect the insulation against ground resistance of photovoltaic array before photovoltaic array is grid-connected.
Fig. 1 is existing a kind of insulation against ground resistance detecting circuit, and resistance R01 and R02 is the insulation against ground resistance of device to be detected, and resistance R30, R40, R50, R60 and switch Q10 form the topological structure of testing circuit.This testing circuit by introducing resistance disturbance, and solves the resistance value of resistance R01 and R02 according to Kirchhoff's law.
But, when the negative output terminal PV-insulation resistance R02 over the ground of photovoltaic array is at below 100K Ω, when positive output end PV+ insulation resistance R01 is over the ground very large simultaneously, the magnitude of voltage at the node N10 place that this sample circuit collects can be very little, before and after switch Q10 adhesive, the voltage variety of node N10 also can be very little, then the resistance error of insulation resistance R01 and R02 calculated also can be very large.
Summary of the invention
In view of this, the invention provides a kind of testing circuit and method of insulation against ground resistance, to solve the larger problem of existing insulation against ground resistance detecting circuit testing result error.
For achieving the above object, the invention provides following technical scheme:
A testing circuit for insulation against ground resistance, comprises positive input terminal, negative input end, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the first switch, sampling conditioning circuit module and processor;
Described positive input terminal is connected with the positive output end of device to be detected, described negative input end is connected with the negative output terminal of described device to be detected, the first end of described first resistance is connected with described positive input terminal, the second end is connected with the first end of described second resistance, second end of described second resistance is connected with the first end of described first switch, and the second end of described first switch is connected with described negative input end; The first end of described 3rd resistance is connected with the second end of described first resistance, the second end is connected with the first end of described 4th resistance, and the second end of described 4th resistance is connected with described negative input end; The input end of described sampling conditioning circuit module is with the first end of described 3rd resistance or the second end is connected, output terminal is connected with described processor;
Described sampling conditioning circuit module is used for the voltage of the Gather and input end when described first switch disconnects and different multiple first voltages of output voltage values, the voltage of Gather and input end when the first switch closes different multiple second voltages of output voltage values;
Described processor is used for selected the first voltage calculated from different multiple first voltages of described magnitude of voltage, selected the second voltage calculated from multiple second voltages that described magnitude of voltage is different, and calculate the insulation against ground resistance of described device positive output end to be detected and the resistance of negative output terminal insulation against ground resistance according to the magnitude of voltage of the first selected voltage and the second voltage.
Preferably, described sampling conditioning circuit module comprises N number of sampling modulate circuit, the input end of described N number of sampling modulate circuit is all connected with the input end of described sampling conditioning circuit module, output terminal is all connected with the output terminal of described sampling conditioning circuit module, wherein, N be greater than 2 natural number, the magnification ratio of described N number of sampling modulate circuit reduces successively;
Maximum and the described magnitude of voltage of described processor selected magnitude of voltage from magnitude of voltage different N the first voltage that described N number of sampling modulate circuit exports is less than or equal to the first voltage of the calculating of threshold voltage, and N number of second voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, the maximum and described magnitude of voltage of selected magnitude of voltage is less than or equal to the second voltage of the calculating of threshold voltage.
Preferably, described sampling conditioning circuit module comprises two sampling modulate circuits, the input end of described two sampling modulate circuits is all connected with the input end of described sampling conditioning circuit module, output terminal is all connected with the output terminal of described sampling conditioning circuit module, wherein, the magnification ratio of the 1st sampling modulate circuit is greater than the magnification ratio of the 2nd sampling modulate circuit;
Described processor judges whether the first voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the first voltage that then described 1st sampling modulate circuit exports is selected the first voltage calculated, if not, then the first voltage that described 2nd sampling modulate circuit exports is selected the first voltage calculated;
Described processor judges whether the second voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the second voltage that then described 1st sampling modulate circuit exports is selected the second voltage calculated, if not, then the second voltage that described 2nd sampling modulate circuit exports is selected the second voltage calculated.
Preferably, described sampling conditioning circuit module also comprises second switch;
When described second switch disconnects, the output terminal of described 1st sampling modulate circuit is connected with described processor, and described 1st sampling modulate circuit exports the first voltage or the second voltage to described processor;
When described second switch closes, the output terminal of described 2nd sampling modulate circuit is connected with described processor, and described 2nd sampling modulate circuit exports the first voltage or the second voltage to described processor.
Preferably, described sampling conditioning circuit module comprises sampling modulate circuit, second switch and the 5th resistance;
Second end of described 5th resistance is connected with described negative input end; When described second switch disconnects, the first end of described 4th resistance is connected with the second end of described 3rd resistance, and described sampling modulate circuit exports first the first voltage and first the first voltage to described processor; When described second switch closes, the first end of described 5th resistance is connected with the second end of described 3rd resistance, and described sampling modulate circuit exports second the first voltage and second the second voltage to described processor;
Described processor judges whether described first the first voltage is less than or equal to threshold voltage, and if so, then first the first voltage is the first voltage calculated, and if not, then described second the first voltage is the first voltage calculated;
Described processor judges whether described first the second voltage is less than or equal to threshold voltage, and if so, then described first the second voltage is the second voltage calculated, and if not, then described second the second voltage is the second voltage calculated.
A detection method for insulation against ground resistance, be applied to the testing circuit of the insulation against ground resistance as above described in any one, described detection method comprises:
Receive multiple first voltage adopting the magnitude of voltage of conditioning circuit module output when the first switch disconnects different and multiple second voltages that the magnitude of voltage of output is different when the first switch closes;
Selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, selected the second voltage calculated from multiple second voltages that described magnitude of voltage is different;
The resistance of the insulation against ground resistance of device positive output end to be detected and the insulation against ground resistance of negative output terminal is calculated according to the first selected voltage and the second voltmeter.
Preferably, when described sampling conditioning circuit module comprises N number of sampling modulate circuit, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Find out the first voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of first voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the first voltage of finding out be the first voltage of selected calculating;
Find out the second voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of second voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the second voltage of finding out be the second voltage of selected calculating.
Preferably, when described sampling conditioning circuit module comprises two sampling modulate circuits, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Judge whether the first voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the first voltage that then described 1st sampling modulate circuit exports is the first voltage of selected calculating, if not, then the first voltage that described 2nd sampling modulate circuit exports is the first voltage of selected calculating;
Judge whether the second voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the second voltage that then described 1st sampling modulate circuit exports is the second voltage of selected calculating, if not, then the second voltage that described 2nd sampling modulate circuit exports is the second voltage of selected calculating.
Preferably, when described sampling conditioning circuit module also comprises second switch, and when the first switch disconnects, disconnect by controlling described second switch or close, receive the first voltage of the 1st sampling modulate circuit output or the first voltage of the 2nd sampling modulate circuit output, when the first switch closes, by controlling described second switch disconnection or closed, receive the second voltage of the 1st sampling modulate circuit output or the second voltage of the 2nd sampling modulate circuit output.
Preferably, when described sampling conditioning circuit module comprises sampling modulate circuit, second switch and the 5th resistance, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Judge whether described first the first voltage is less than or equal to threshold voltage, if so, then described first the first voltage is the first voltage of selected calculating, and if not, then described second the first voltage is the first voltage of selected calculating;
Judge whether described first the second voltage is less than or equal to threshold voltage, if so, then described first the second voltage is the second voltage of selected calculating, and if not, then described second the second voltage is the second voltage of selected calculating.
Preferably, when the first switch disconnects, disconnect by controlling described second switch or close, receiving first the first voltage or first second voltage of described sampling modulate circuit output;
When the first switch closes, disconnect by controlling described second switch or close, receiving second the first voltage or second second voltage of described sampling modulate circuit output.
Compared with prior art, technical scheme provided by the present invention has the following advantages:
The testing circuit of insulation against ground resistance provided by the present invention and method, sampling conditioning circuit module gathers different multiple first voltage of output voltage values after the voltage of same node or different multiple second voltages of output voltage values, not only sampling precision can be improved, can also when device under test negative output terminal insulation against ground resistance be less, the first voltage that selected magnitude of voltage is larger from multiple first voltage or the second voltage or the second voltage calculate the resistance of device positive output end to be detected and negative output terminal insulation against ground resistance, thus the error of the insulation against ground resistance calculated can be reduced.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.
Fig. 1 is the circuit diagram of the testing circuit of existing a kind of insulation against ground resistance;
The circuit diagram of a kind of insulation against ground resistance detecting circuit that Fig. 2 provides for the embodiment of the present invention one;
The circuit diagram of the another kind of insulation against ground resistance detecting circuit that Fig. 3 provides for the embodiment of the present invention one;
The circuit diagram of a kind of insulation against ground resistance detecting circuit that Fig. 4 provides for the embodiment of the present invention two;
The circuit diagram of the another kind of insulation against ground resistance detecting circuit that Fig. 5 provides for the embodiment of the present invention two;
The circuit diagram of a kind of insulation against ground resistance detecting circuit that Fig. 6 provides for the embodiment of the present invention three;
The circuit diagram of the another kind of insulation against ground resistance detecting circuit that Fig. 7 provides for the embodiment of the present invention three;
The circuit diagram of a kind of insulation against ground resistance detecting circuit that Fig. 8 provides for the embodiment of the present invention four;
The circuit diagram of the another kind of insulation against ground resistance detecting circuit that Fig. 9 provides for the embodiment of the present invention four;
The process flow diagram of a kind of insulation against ground resistor detection method that Figure 10 provides for the embodiment of the present invention five.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Embodiment one
Present embodiments provide a kind of testing circuit of insulation against ground resistance, for detecting the insulation against ground resistance of device to be detected.This testing circuit comprises positive input terminal PV+, negative input end PV-, the first resistance R1, the second resistance R2, the 3rd resistance R3, the 4th resistance R4, the first switch Q1, sampling conditioning circuit module and processor CPU.
For conditioning circuit module of sampling, there are two sampling modulate circuits in the present embodiment to be described.As shown in Figure 2, the first end of the first resistance R1 is connected with positive input terminal PV+, the second end is connected with the first end of the second resistance R2, and second end of the second resistance R2 is connected with the first end of the first switch Q1, and second end of the first switch Q1 is connected with negative input end PV-; The first end of the 3rd resistance R3 is with second end of the first resistance R1 and node N1 is connected, the second end is connected with the first end of the 4th resistance R4, and second end of the 4th resistance R4 is connected with negative input end PV-; The input end of two sampling modulate circuits is all with second end of the 3rd resistance R3 and node N2 is connected, output terminal is all connected with processor CPU.Wherein, processor CPU can control the disconnection of the first switch Q1 and close.
In the present embodiment only with device to be detected for photovoltaic DC-to-AC converter is described, but be not limited in this.Suppose that the insulation against ground resistance of photovoltaic DC-to-AC converter DC side positive output end be the insulation against ground resistance of R10 and negative output terminal is R20, the positive input terminal PV+ of testing circuit is connected with the positive output end of photovoltaic DC-to-AC converter, after negative input end PV-is connected with the negative output terminal of photovoltaic DC-to-AC converter, resistance R10 will be in parallel with the first resistance R1, resistance R20 will be in parallel with the second resistance R2 and the first switch Q1, thus can calculate the resistance of resistance R10 and R20 according to Kirchhoff's second law or current law.
In the present embodiment, each sampling modulate circuit all can export one first voltage when the first switch Q1 disconnects to processor CPU, exports one second voltage when the first switch Q1 closes to processor CPU.Because the magnification ratio of each sampling modulate circuit is different, therefore, the magnitude of voltage of the first voltage that each sampling modulate circuit exports is different, and the magnitude of voltage of the second voltage of output is also different.The present invention does not limit the concrete structure of sampling modulate circuit, as long as it can sampled voltage signal, and amplifies the voltage signal of sampling.Further, the magnification ratio of the sampling modulate circuit in the present embodiment is all greater than 1.
Processor CPU is used for selected the first voltage calculated the first voltage exported from two sampling modulate circuits, selected the second voltage calculated from the second voltage that two sampling modulate circuits export, and calculate the resistance of photovoltaic DC-to-AC converter positive output end insulation against ground resistance R10 and the resistance of negative output terminal insulation against ground resistance R20 according to the first selected voltage, the second voltage, magnitude of voltage U0, the first resistance R1 between positive input terminal PV+ and negative input end PV-to the resistance of the 4th resistance R4 and Kirchhoff's law.
Wherein, the detailed process calculating resistance R10 and R20 is: processor CPU controls the first switch Q1 and disconnects, and obtain the first voltage U 30 of the 1st sampling modulate circuit output and the first voltage U 31 of the 2nd sampling modulate circuit output, first voltage U 30 and U31 are the sampling modulate circuit acquisition node N2 i.e. voltage U 20 at the 4th resistance R4 two ends and the voltage after amplifying according to the magnification ratio preset, and U30=k1*U20, U31=k2*U20, k1 is the magnification ratio of the 1st sampling modulate circuit, k2 is the magnification ratio of the 2nd sampling modulate circuit, wherein, k1 is far longer than k2.
Then processor CPU control the first switch Q1 close, and the second voltage U the 40,2nd sampling modulate circuit obtaining the output of the 1st sampling modulate circuit exports the second voltage U 41, and U40=k1*U21, U41=k2*U21, U21 are the voltage that the first switch Q1 closes posterior nodal point N2.
The first voltage U 30 of exporting according to the 1st sampling modulate circuit of preprocessor CPU whether be less than or equal to the result of determination of threshold voltage, determine that the first voltage calculated is the first voltage U 31 that the first voltage U 30 of exporting of the 1st sampling modulate circuit or the 2nd sampling modulate circuit export; And the result of determination of threshold voltage whether is less than or equal to according to the second voltage U 40 of the 1st sampling modulate circuit output, determine that the second voltage calculated is the second voltage U 40 of the 1st sampling modulate circuit output or the second voltage U 40 of the 2nd sampling modulate circuit output.
In the present embodiment, the voltage that the sampling modulate circuit preferentially selecting magnification ratio larger exports, to reduce the error of the insulation against ground resistance calculated.Thus, first judge whether the first voltage U 30 that the 1st sampling modulate circuit exports is less than or equal to threshold voltage, if the first voltage U 30 is less than or equal to threshold voltage, then selected first voltage U 30 is the first voltage calculated, and the first voltage U 30 is substituted into formula
In calculate the voltage U 10 of N1 node when the first switch Q1 disconnects, if the first voltage U 30 is greater than threshold voltage, then the first voltage U 31 that selected 2nd sampling modulate circuit exports be the first voltage calculated, and by the value of the first voltage U 31 substitution formula
In calculate the voltage U 10 of N1 node when the first switch Q1 disconnects.Wherein, this threshold voltage is the input voltage upper limit of processor CPU, and because the input voltage upper limit of different processors is different, therefore, the threshold voltage in the present embodiment need set according to actual conditions.Because k1 is far longer than k2, therefore, even if the first voltage U 30 is greater than threshold voltage, the second voltage U 31 also can be less than or equal to threshold voltage.
Equally, if the second voltage U 40 of the 1st sampling modulate circuit output is less than or equal to threshold voltage, then selected second voltage U 40 is the second voltage calculated, and the second voltage U 40 is substituted into formula
In calculate the voltage U 11 of N1 node when the first switch Q1 closes, if the second voltage U 40 is greater than threshold voltage, then the second voltage U 41 that selected 2nd sampling modulate circuit exports be the first voltage of calculating, and the first voltage U 41 is substituted into formula
In calculate the voltage U 11 of N1 node when the first switch Q1 closes.
List following formula one and formula two according to Kirchhoff's law, wherein, formula one is the Kirchhoff formula listed of circuit structure when disconnecting according to the first switch Q1, and formula two is Kirchhoff formulas that circuit structure when closing according to the first switch Q1 is listed.
Due in these two equations only resistance R10 and R20 be unknown number, therefore, voltage U 0 between the positive input terminal PV+ that the voltage U 10 calculated and voltage U 11, measurement obtain by processor CPU and negative input end PV-and the resistance of the first known resistance R1, the second resistance R2, the 3rd resistance R3 and the 4th resistance R4 substitute into above-mentioned formula one and formula two, can calculate the positive output end insulation against ground resistance R10 of photovoltaic DC-to-AC converter DC side and the resistance of negative output terminal insulation against ground resistance R20.
After obtaining insulation against ground resistance R10 and R20, can also according to formula
calculate the insulation impedance R of photovoltaic DC-to-AC converter DC side
eq, and according to the testing result of different operating mode, judge R
eqwhether be greater than protection threshold value R
limit.If insulation impedance value R
eqbe greater than protection threshold value R
limit, then illustrate that the insulation against ground of photovoltaic DC-to-AC converter is functional, can normal grid-connected work.If insulation impedance value R
eqbe less than protection threshold value R
limit, then illustrate that photovoltaic DC-to-AC converter insulation against ground is broken down, and normally cannot be incorporated into the power networks, need to send alarm failure signal, prompting staff keeps in repair.
In another embodiment of the present embodiment, as shown in Figure 3, the input end of two sampling modulate circuits is all connected with the first end of the 3rd resistance R3.
When first switch Q1 disconnects, the first voltage U 30=k1*U10 that the 1st sampling modulate circuit exports, the first voltage U 31=k2*U10 that the 2nd sampling modulate circuit exports; When first switch Q1 closes, the second voltage U 40=k1*U11 that the 1st sampling modulate circuit exports, the second voltage U 41=k2*U11 that the 2nd sampling modulate circuit exports.
If the first voltage U 30 of the 1st sampling modulate circuit output is less than or equal to threshold voltage, then selected first voltage U 31 is the first voltage calculated, and calculates the voltage of N1 node when the first switch Q1 disconnects
if the first voltage U 30 is greater than threshold voltage, then the first voltage U 31 that selected 2nd sampling modulate circuit exports is the first voltage calculated, and calculates the voltage of N1 node when the first switch Q1 disconnects
If the second voltage U 40 of the 1st sampling modulate circuit output is less than or equal to threshold voltage, then selected second voltage U 40 is the second voltage calculated, and calculates the voltage of N1 node when the first switch Q1 closes
if the second voltage U 40 is greater than threshold voltage, then the second voltage U 41 that selected 2nd sampling modulate circuit exports is the first voltage calculated, and calculates the voltage of N1 node when the first switch Q1 closes
Afterwards by the voltage U 10 calculated, voltage U 11 and known voltage U 0, resistance R1, R2, R3 and R4 substitute into above-mentioned Kirchhoff formula one and formula two calculates R10 and R20.
The testing circuit of the insulation against ground resistance that the present embodiment provides, the collection of voltage is carried out by multiple sampling modulate circuit, not only sampling precision can be improved, can also when device under test output terminal insulation against ground resistance be less, the resistance that the first voltage that the larger sampling modulate circuit of magnification ratio exports or the second voltage calculate device positive output end to be detected and negative output terminal insulation against ground resistance is selected, to reduce the error of the insulation against ground resistance calculated from multiple sampling modulate circuit.
Embodiment two
Present embodiments provide a kind of testing circuit of insulation against ground resistance, this testing circuit is identical with the structure of the testing circuit in embodiment one, its difference is, sampling conditioning circuit module in the present embodiment comprises N number of sampling modulate circuit, the input end of this N number of sampling modulate circuit is connected with same node, as shown in Figure 4, the input end of this N number of sampling modulate circuit is all with second end of the 3rd resistance R3 and node N2 is connected, output terminal is all connected with processor CPU.
The computation process of the testing circuit that the present embodiment provides is: control the first switch Q1 and disconnect, obtain the 1st sampling modulate circuit and export the first voltage U 31=k1*U20, obtain the 2nd sampling modulate circuit and export the first voltage U 32=k2*U20, obtain the 3rd sampling modulate circuit export first voltage U 33=k3*U20... obtain n-th sampling modulate circuit export the first voltage U 3n=kn*U20, wherein, k1 is the magnification ratio of the 1st sampling modulate circuit, k2 is the magnification ratio of the 2nd sampling modulate circuit ... kn is the magnification ratio of the n-th sampling modulate circuit, and k1, k2...kn reduces successively.
Control the first switch Q1 to close, obtain the second voltage U 41=k1*U21 that the 1st sampling modulate circuit exports, obtain the second voltage U 42=k2*U21 that the 2nd sampling modulate circuit exports, the second voltage U 4n=kn*U21 that the second voltage U 43=k3*U21... acquisition n-th sampling modulate circuit obtaining the output of the 3rd sampling modulate circuit exports.
Preprocessor CPU according to magnitude of voltage, maximum and magnitude of voltage is less than or equal to the standard of threshold voltage, selected the first voltage calculated from the first voltage that N number of sampling modulate circuit exports, selected the second voltage calculated from the second voltage that N number of sampling modulate circuit exports.Namely from the first voltage U 31 to U3n, find out maximum and this magnitude of voltage of magnitude of voltage be less than or equal to the first voltage of threshold voltage as the first voltage calculated, from the second voltage U 41 to U4n, find out that magnitude of voltage is maximum and this magnitude of voltage is less than or equal to the second voltage of threshold voltage as the second voltage calculated.
Suppose that the first voltage found out is the first voltage U 33 that the 3rd sampling modulate circuit exports, the second voltage found out is the second voltage U 43 that the 3rd sampling modulate circuit exports, then the first voltage U 33 is substituted into formula
in calculate the voltage U 10 of N1 node when the first switch Q1 disconnects, the second voltage U 43 is substituted into formula
in calculate the voltage U 11 of N1 node when the first switch Q1 closes.
Afterwards by the voltage U 10 calculated, voltage U 11 and known voltage U 0, resistance R1, R2, R3 and R4 substitute into above-mentioned Kirchhoff formula one and formula two calculates R10 and R20.
In another embodiment of the present embodiment, as shown in Figure 5, the input end of this N number of sampling modulate circuit is all with the first end of the 3rd resistance R3 and node N1 is connected, output terminal is all connected with processor CPU.First switch Q1 disconnect time, the 1st sampling modulate circuit export the first voltage U 31=k1*U10, the 2nd sampling modulate circuit export the first voltage U 32=k2*U10... n-th sample modulate circuit export the first voltage U 3n=kn*U10; When first switch Q1 closes, the second voltage U 41=k1*U11 that the 1st sampling modulate circuit exports, the second voltage U 42=k2*U11 that the 2nd sampling modulate circuit exports ... the second voltage U 4n=kn*U11 that n-th sampling modulate circuit exports.
From the first voltage U 31 to U3n, find out maximum and this magnitude of voltage of magnitude of voltage be less than or equal to the first voltage of threshold voltage as the first voltage calculated, from the second voltage U 41 to U4n, find out that magnitude of voltage is maximum and this magnitude of voltage is less than or equal to the second voltage of threshold voltage as the second voltage calculated.Suppose that the first voltage found out is the first voltage U 33 that the 3rd sampling modulate circuit exports, the second voltage found out is the second voltage U 43 that the 3rd sampling modulate circuit exports, and so, can calculate the voltage of N1 node when the first switch Q1 disconnects
calculate the voltage of N1 node when the first switch Q1 closes
Afterwards by the voltage U 10 calculated, voltage U 11 and known voltage U 0, resistance R1, R2, R3 and R4 substitute into above-mentioned formula one and formula two calculates R10 and R20.
The testing circuit of the insulation against ground resistance that the present embodiment provides, the collection of voltage is carried out by multiple sampling modulate circuit, not only sampling precision can be improved, can also when device under test output terminal insulation against ground resistance be less, the resistance that the first voltage that the larger sampling modulate circuit of magnification ratio exports or the second voltage calculate device positive output end to be detected and negative output terminal insulation against ground resistance is selected, to reduce the error of the insulation against ground resistance calculated from multiple sampling modulate circuit.
Embodiment three
The testing circuit of the insulation against ground resistance that the present embodiment provides is substantially identical with the structure of the testing circuit that embodiment one provides, its difference is, as shown in Figure 6 and Figure 7, sampling conditioning circuit module in the present embodiment also comprises second switch Q2, one end of this second switch Q2 is connected with processor CPU, and the other end is connected with the output terminal of the 1st modulate circuit of sampling or the output terminal of the 2nd modulate circuit of sampling connects.
That is, when second switch Q2 disconnects, the output terminal of the 1st sampling modulate circuit is connected with processor CPU, and exports the first voltage or the second voltage to processor CPU; When second switch Q2 closes, the output terminal of the 2nd sampling modulate circuit is connected with processor CPU, and exports the first voltage or the second voltage to processor CPU, so just can save an input port of processor CPU.
When the first switch Q1 disconnects, control second switch Q2 and disconnect, obtain the first voltage U 30 that the 1st sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain the first voltage U 31 that the 2nd sampling modulate circuit exports.
When the first switch Q1 closes, control second switch Q2 and disconnect, obtain the second voltage U 40 that the 1st sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain the second voltage U 41 that the 2nd sampling modulate circuit exports.
In the present embodiment selected the first voltage calculated and the process of the second voltage and the computation process of insulation against ground resistance R10 with R20 identical with embodiment one, do not repeat them here.
The testing circuit of the insulation against ground resistance that the present embodiment provides, the collection of voltage is carried out by multiple sampling modulate circuit, not only sampling precision can be improved, can also when device under test output terminal insulation against ground resistance be less, the resistance that the first voltage that the larger sampling modulate circuit of magnification ratio exports or the second voltage calculate device positive output end to be detected and negative output terminal insulation against ground resistance is selected, to reduce the error of the insulation against ground resistance calculated from multiple sampling modulate circuit.
Embodiment four
Present embodiments provide a kind of testing circuit of insulation against ground resistance, the testing circuit that this embodiment provides is substantially identical with the testing circuit that embodiment one provides, its difference is, this sampling conditioning circuit module comprises sampling modulate circuit, second switch Q2 and a 5th resistance R5, the resistance of the 5th resistance R5 is different with the resistance of the 4th resistance R4, and preferred 5th resistance R5 is greater than the 4th resistance R4.
As shown in Figure 8, second end of the 5th resistance R5 is connected with negative input end PV-, one end of second switch Q2 is connected with second end of the 3rd resistance R3, the other end is connected with the first end of the 4th resistance R4 or the 5th resistance R5, and the input end of sampling modulate circuit is connected with second end of the 3rd resistance R3.When second switch Q2 disconnects, the first end of the 4th resistance R4 is connected with second end of the 3rd resistance R3, and sampling modulate circuit exports first the first voltage or first the second voltage to processor CPU; When second switch Q2 closes, the first end of the 5th resistance R5 is connected with second end of the 3rd resistance R3, and sampling modulate circuit exports second the first voltage and second the second voltage to processor CPU.
When the first switch Q1 disconnects, control second switch Q2 and disconnect, obtain first the first voltage U 30 that sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain second the first voltage U 31 that sampling modulate circuit exports.
When the first switch Q1 closes, control second switch Q2 and disconnect, obtain first the second voltage U 40 that sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain second the second voltage U 41 that sampling modulate circuit exports.
Due to the closed front and back of second switch Q2, the resistance of the resistance that N1 node connects is different, namely second switch Q2 disconnect or when closing the voltage of N1 node different, therefore, even if adopt the voltage of modulate circuit to N1 node of sampling to gather, but first the first voltage U 30 that sampling modulate circuit exports is not identical with the magnitude of voltage of second the first voltage U 31, and first the second voltage U 40 is not identical with the magnitude of voltage of second the second voltage U 41.
Judge whether first the first voltage U 30 is less than or equal to threshold voltage afterwards, if so, then selected first the first voltage U 30 is the first voltage calculated, and the value of first the first voltage U 30 is substituted into formula
In calculate the voltage U 10 of N1 node when the first switch Q1 disconnects, if first the first voltage U 30 is greater than threshold voltage, then second the first voltage U 31 is substituted into formula
in calculate the voltage U 101 of N1 node when the first switch Q1 disconnects.
Equally, if first the second voltage U 40 is less than or equal to threshold voltage, then first the second voltage U 40 is substituted into formula
In calculate the voltage U 11 of N1 node when the first switch Q1 closes, if the second voltage U 40 is greater than threshold voltage, then second the second voltage U 41 is substituted into formula
in calculate the voltage U 111 of N1 node when the first switch Q1 closes.
Afterwards by the voltage U 10 calculated or U101, voltage U 11 or U111 and known voltage U 0, resistance R1, R2, R3 and R4 substitute into above-mentioned Kirchhoff formula one and formula two calculates R10 and R20.
Equally, in another embodiment of the present embodiment, as shown in Figure 9, the input end of sampling modulate circuit is connected with the first end of the 3rd resistance R3.
Equally, when the first switch Q1 disconnects, control second switch Q2 and disconnect, obtain first the first voltage U 30 that sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain second the first voltage U 31 that sampling modulate circuit exports.
When the first switch Q1 closes, control second switch Q2 and disconnect, obtain first the second voltage U 40 that sampling modulate circuit exports, control second switch Q2 afterwards and close, obtain second the second voltage U 41 that sampling modulate circuit exports.
Judge whether first the first voltage U 30 is less than or equal to threshold voltage afterwards, if so, then selected first the first voltage U 30 is the first voltage calculated, and the value of first the first voltage U 30 is substituted into formula
in calculate the voltage U 10 of N1 node when the first switch Q1 disconnects, if first the first voltage U 30 is greater than threshold voltage, then second the first voltage U 31 is substituted into formula
in calculate the voltage U 101 of N1 node when the first switch Q1 disconnects.
Equally, if first the second voltage U 40 is less than or equal to threshold voltage, then first the second voltage U 40 is substituted into formula
in calculate the voltage U 11 of N1 node when the first switch Q1 closes, if the second voltage U 40 is greater than threshold voltage, then second the second voltage U 41 is substituted into formula
in calculate the voltage U 111 of N1 node when the first switch Q1 closes.
Afterwards by the voltage U 10 calculated or U101, voltage U 11 or U111 and known voltage U 0, resistance R1, R2, R3 and R4 substitute into above-mentioned Kirchhoff formula one and formula two calculates R10 and R20.
The testing circuit of the insulation against ground resistance that the present embodiment provides, sampling conditioning circuit module gathers different multiple first voltage of output voltage values after the voltage of same node or different multiple second voltages of output voltage values, not only sampling precision can be improved, can also when device under test negative output terminal insulation against ground resistance be less, the first voltage that selected magnitude of voltage is larger from multiple first voltage or the second voltage or the second voltage calculate the resistance of device positive output end to be detected and negative output terminal insulation against ground resistance, thus the error of the insulation against ground resistance calculated can be reduced.
Embodiment five
Present embodiments provide a kind of detection method of insulation against ground resistance, be applied to the testing circuit of the insulation against ground resistance that above-mentioned any embodiment provides, as shown in Figure 10, described detection method comprises:
S901: receive multiple first voltage adopting the magnitude of voltage of conditioning circuit module output when the first switch disconnects different and multiple second voltages that the magnitude of voltage of output is different when the first switch closes;
S902: selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, selected the second voltage calculated from multiple second voltages that described magnitude of voltage is different;
S903: the resistance calculating the insulation against ground resistance of device positive output end to be detected and the insulation against ground resistance of negative output terminal according to the first selected voltage and the second voltmeter.
Be described for the testing circuit shown in Fig. 2 below, the sampling conditioning circuit module in this testing circuit comprises two sampling modulate circuits and namely comprises the 1st sampling modulate circuit and the 2nd sampling modulate circuit.
First, processor CPU controls the first switch Q1 and disconnects, and obtains the first voltage U 30 of the 1st sampling modulate circuit output and the first voltage U 31, U30=k1*U20, U31=k2*U20 of the 2nd sampling modulate circuit output.
Then processor CPU controls the first switch Q1 and closes, and obtains the second voltage U the 40,2nd sampling modulate circuit that the 1st sampling modulate circuit export and export the second voltage U 41, and U40=k1*U21, U41=k2*U21.
Preprocessor CPU judge the 1st sampling modulate circuit export the first voltage U 30 whether be less than or equal to threshold voltage, if the first voltage U 30 is less than or equal to threshold voltage, then selected first voltage U 30 is the first voltage calculated, and the first voltage U 30 is substituted into formula
In calculate the voltage U 10 of N1 node when the first switch Q1 disconnects, if the first voltage U 30 is greater than threshold voltage, then the first voltage U 31 that selected 2nd sampling modulate circuit exports be the first voltage calculated, and by the value of the first voltage U 31 substitution formula
In calculate the voltage U 10 of N1 node when the first switch Q1 disconnects.
Equally, judge whether the second voltage U 40 that the 1st sampling modulate circuit exports is less than or equal to threshold voltage, if so, then selected second voltage U 40 is the second voltage calculated, and the second voltage U 40 is substituted into formula
In calculate the voltage U 11 of N1 node when the first switch Q1 closes, if the second voltage U 40 is greater than threshold voltage, then the second voltage U 41 that selected 2nd sampling modulate circuit exports be the first voltage of calculating, and the first voltage U 41 is substituted into formula
In calculate the voltage U 11 of N1 node when the first switch Q1 closes.
After the voltage U 10 calculated and voltage U 11, the resistance of the voltage U 0 between the positive input terminal PV+ that U10, U11, measurement obtain by processor CPU and negative input end PV-and the first known resistance R1, the second resistance R2, the 3rd resistance R3 and the 4th resistance R4 substitutes into above-mentioned Kirchhoff formula one and formula two, can calculate the positive output end insulation against ground resistance R10 of photovoltaic DC-to-AC converter DC side and the resistance of negative output terminal insulation against ground resistance R20.
In the detection method that the present embodiment provides, after obtaining insulation against ground resistance R10 and R20, can also according to formula
calculate the insulation impedance R of photovoltaic DC-to-AC converter DC side
eq, and judge R
eqwhether be greater than protection threshold value R
limit.If insulation impedance value R
eqbe greater than protection threshold value R
limit, then illustrate that the insulation against ground of photovoltaic DC-to-AC converter is functional, can normal grid-connected work.If insulation impedance value R
eqbe less than protection threshold value R
limit, then illustrate that photovoltaic DC-to-AC converter insulation against ground is broken down, and normally cannot be incorporated into the power networks, need to send alarm failure signal, prompting staff keeps in repair.Wherein, threshold value R is protected
limitcan set according to concrete operating mode.
Compared with the testing circuit shown in Fig. 2, sampling conditioning circuit module shown in Fig. 4 comprises N number of sampling modulate circuit, now, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Find out the first voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of first voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the first voltage of finding out be the first voltage of selected calculating;
Find out the second voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of second voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the second voltage of finding out be the second voltage of selected calculating.
The computation process of the testing circuit shown in Fig. 4 and Fig. 5 has been described in detail in embodiment two, does not repeat them here.
Compared with the testing circuit shown in Fig. 2, sampling conditioning circuit module shown in Fig. 6 also comprises second switch Q2, based on this, when the first switch Q1 disconnects, processor CPU is by controlling the disconnection or closed of second switch Q2, receive the first voltage of the 1st sampling modulate circuit output or the first voltage of the 2nd sampling modulate circuit output, when the first switch Q1 closes, processor CPU, by the disconnection or closed of control second switch Q2, receives the second voltage of the 1st sampling modulate circuit output or the second voltage of the 2nd sampling modulate circuit output.The computation process of the testing circuit shown in Fig. 6 and Fig. 7 has been described in detail in embodiment three, does not repeat them here.
Compared with the testing circuit shown in Fig. 2, sampling conditioning circuit module shown in Fig. 8 or Fig. 9 comprises sampling modulate circuit, second switch Q2 and a 5th resistance R5, when the first switch Q1 disconnects, processor CPU disconnects by controlling second switch Q2 or closes, and receives first the first voltage or first second voltage of the output of sampling modulate circuit; When the first switch Q1 closes, processor CPU disconnects by controlling second switch Q2 or closes, and receives second the first voltage or second second voltage of the output of sampling modulate circuit.
Further, the testing circuit shown in Fig. 8 or Fig. 9, when detecting, selectes the first voltage calculated from multiple first voltages that described magnitude of voltage is different, and from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Judge whether first the first voltage is less than or equal to threshold voltage, if so, then first the first voltage is the first selected voltage, and if not, then second the first voltage is the first selected voltage; Judge whether first the second voltage is less than or equal to threshold voltage, if so, then first the second voltage is the second selected voltage, and if not, then second the second voltage is the second selected voltage.
The computation process of the testing circuit shown in Fig. 8 or Fig. 9 has been described in detail in embodiment four, does not repeat them here.
The detection method of the insulation against ground resistance that the present embodiment provides, sampling conditioning circuit module gathers different multiple first voltage of output voltage values after the voltage of same node or different multiple second voltages of output voltage values, not only sampling precision can be improved, can also when device under test negative output terminal insulation against ground resistance be less, the first voltage that selected magnitude of voltage is larger from multiple first voltage or the second voltage or the second voltage calculate the resistance of device positive output end to be detected and negative output terminal insulation against ground resistance, thus the error of the insulation against ground resistance calculated can be reduced.
In this instructions, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar portion mutually see.For device disclosed in embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part illustrates see method part.
To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (11)
1. a testing circuit for insulation against ground resistance, is characterized in that, comprises positive input terminal, negative input end, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the first switch, sampling conditioning circuit module and processor;
Described positive input terminal is connected with the positive output end of device to be detected, described negative input end is connected with the negative output terminal of described device to be detected, the first end of described first resistance is connected with described positive input terminal, the second end is connected with the first end of described second resistance, second end of described second resistance is connected with the first end of described first switch, and the second end of described first switch is connected with described negative input end; The first end of described 3rd resistance is connected with the second end of described first resistance, the second end is connected with the first end of described 4th resistance, and the second end of described 4th resistance is connected with described negative input end; The input end of described sampling conditioning circuit module is with the first end of described 3rd resistance or the second end is connected, output terminal is connected with described processor;
Described sampling conditioning circuit module is used for the voltage of the Gather and input end when described first switch disconnects and different multiple first voltages of output voltage values, the voltage of Gather and input end when the first switch closes different multiple second voltages of output voltage values;
Described processor is used for selected the first voltage calculated from different multiple first voltages of described magnitude of voltage, selected the second voltage calculated from multiple second voltages that described magnitude of voltage is different, and calculate the insulation against ground resistance of described device positive output end to be detected and the resistance of negative output terminal insulation against ground resistance according to the first selected voltage and the second voltage.
2. testing circuit according to claim 1, it is characterized in that, described sampling conditioning circuit module comprises N number of sampling modulate circuit, the input end of described N number of sampling modulate circuit is all connected with the input end of described sampling conditioning circuit module, output terminal is all connected with the output terminal of described sampling conditioning circuit module, wherein, N be greater than 2 natural number, the magnification ratio of described N number of sampling modulate circuit reduces successively;
N number of first voltage that the magnitude of voltage that described processor exports from described N number of sampling modulate circuit is different, the maximum and described magnitude of voltage of selected magnitude of voltage is less than or equal to the first voltage of the calculating of threshold voltage, and N number of second voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, the maximum and described magnitude of voltage of selected magnitude of voltage is less than or equal to the second voltage of the calculating of threshold voltage.
3. testing circuit according to claim 1, it is characterized in that, described sampling conditioning circuit module comprises two sampling modulate circuits, the input end of described two sampling modulate circuits is all connected with the input end of described sampling conditioning circuit module, output terminal is all connected with the output terminal of described sampling conditioning circuit module, wherein, the magnification ratio of the 1st sampling modulate circuit is greater than the magnification ratio of the 2nd sampling modulate circuit;
Described processor judges whether the first voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the first voltage that then described 1st sampling modulate circuit exports is selected the first voltage calculated, if not, then the first voltage that described 2nd sampling modulate circuit exports is selected the first voltage calculated;
Described processor judges whether the second voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the second voltage that then described 1st sampling modulate circuit exports is selected the second voltage calculated, if not, then the second voltage that described 2nd sampling modulate circuit exports is selected the second voltage calculated.
4. testing circuit according to claim 3, is characterized in that, described sampling conditioning circuit module also comprises second switch;
When described second switch disconnects, the output terminal of described 1st sampling modulate circuit is connected with described processor, and described 1st sampling modulate circuit exports the first voltage or the second voltage to described processor;
When described second switch closes, the output terminal of described 2nd sampling modulate circuit is connected with described processor, and described 2nd sampling modulate circuit exports the first voltage or the second voltage to described processor.
5. testing circuit according to claim 1, is characterized in that, described sampling conditioning circuit module comprises sampling modulate circuit, second switch and the 5th resistance;
Second end of described 5th resistance is connected with described negative input end; When described second switch disconnects, the first end of described 4th resistance is connected with the second end of described 3rd resistance, and described sampling modulate circuit exports first the first voltage and first the first voltage to described processor; When described second switch closes, the first end of described 5th resistance is connected with the second end of described 3rd resistance, and described sampling modulate circuit exports second the first voltage and second the second voltage to described processor;
Described processor judges whether described first the first voltage is less than or equal to threshold voltage, and if so, then first the first voltage is the first voltage calculated, and if not, then described second the first voltage is the first voltage calculated;
Described processor judges whether described first the second voltage is less than or equal to threshold voltage, and if so, then described first the second voltage is the second voltage calculated, and if not, then described second the second voltage is the second voltage calculated.
6. a detection method for insulation against ground resistance, is characterized in that, be applied to the testing circuit of the insulation against ground resistance described in any one of Claims 1 to 5, described detection method comprises:
Receive multiple first voltage adopting the magnitude of voltage of conditioning circuit module output when the first switch disconnects different and multiple second voltages that the magnitude of voltage of output is different when the first switch closes;
Selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, selected the second voltage calculated from multiple second voltages that described magnitude of voltage is different;
The resistance of the insulation against ground resistance of device positive output end to be detected and the insulation against ground resistance of negative output terminal is calculated according to the first selected voltage and the second voltmeter.
7. method according to claim 6, it is characterized in that, when described sampling conditioning circuit module comprises N number of sampling modulate circuit, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Find out the first voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of first voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the first voltage of finding out be the first voltage of selected calculating;
Find out the second voltage that the maximum and magnitude of voltage of magnitude of voltage is less than or equal to threshold voltage N number of second voltage that the magnitude of voltage exported from described N number of sampling modulate circuit is different, described in the second voltage of finding out be the second voltage of selected calculating.
8. method according to claim 6, it is characterized in that, when described sampling conditioning circuit module comprises two sampling modulate circuits, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Judge whether the first voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the first voltage that then described 1st sampling modulate circuit exports is the first voltage of selected calculating, if not, then the first voltage that described 2nd sampling modulate circuit exports is the first voltage of selected calculating;
Judge whether the second voltage that described 1st sampling modulate circuit exports is less than or equal to threshold voltage, if, the second voltage that then described 1st sampling modulate circuit exports is the second voltage of selected calculating, if not, then the second voltage that described 2nd sampling modulate circuit exports is the second voltage of selected calculating.
9. method according to claim 8, it is characterized in that, when described sampling conditioning circuit module also comprises second switch, and when the first switch disconnects, disconnect by controlling described second switch or close, receive the first voltage of the 1st sampling modulate circuit output or the first voltage of the 2nd sampling modulate circuit output, when the first switch closes, by controlling described second switch disconnection or closed, receive the second voltage of the 1st sampling modulate circuit output or the second voltage of the 2nd sampling modulate circuit output.
10. method according to claim 6, it is characterized in that, when described sampling conditioning circuit module comprises sampling modulate circuit, second switch and the 5th resistance, selected the first voltage calculated from multiple first voltages that described magnitude of voltage is different, from multiple second voltages that described magnitude of voltage is different, the process of selected the second voltage calculated comprises:
Judge whether described first the first voltage is less than or equal to threshold voltage, if so, then described first the first voltage is the first voltage of selected calculating, and if not, then described second the first voltage is the first voltage of selected calculating;
Judge whether described first the second voltage is less than or equal to threshold voltage, if so, then described first the second voltage is the second voltage of selected calculating, and if not, then described second the second voltage is the second voltage of selected calculating.
11. methods according to claim 10, is characterized in that, when the first switch disconnects, disconnect by controlling described second switch or close, receiving first the first voltage or first second voltage of described sampling modulate circuit output;
When the first switch closes, disconnect by controlling described second switch or close, receiving second the first voltage or second second voltage of described sampling modulate circuit output.
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