CN104422825A - Method and method for detecting insulation resistance against ground of DC power supply - Google Patents

Method and method for detecting insulation resistance against ground of DC power supply Download PDF

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CN104422825A
CN104422825A CN201310383387.9A CN201310383387A CN104422825A CN 104422825 A CN104422825 A CN 104422825A CN 201310383387 A CN201310383387 A CN 201310383387A CN 104422825 A CN104422825 A CN 104422825A
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resistance
circuit
threshold value
voltage
output terminal
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CN104422825B (en
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邱宝象
李霖
资小林
李晟
林光钟
张军
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ZHEJIANG WANXIANG SOLAR CO Ltd
Wanxiang Group Corp
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ZHEJIANG WANXIANG SOLAR CO Ltd
Wanxiang Group Corp
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Abstract

The invention discloses a method and a method for detecting insulation resistance against ground of a DC power supply. The device comprises a resistance bridge circuit, a voltage sampling circuit, a filtering amplifying circuit, an analog signal isolation module, and a threshold comparison circuit. A DC power supply, the resistance bridge circuit, the voltage sampling circuit, the filtering amplifying circuit, the analog signal isolation module, and the threshold comparison circuit are connected in sequence. Through the resistance bridge circuit, the method obtains voltage signals related to insulation resistance against ground of the anode and the cathode of the DC power supply. Through sampling, filtering, amplifying, and isolation processing on the voltage signals, and finally through the threshold comparison circuit, the method determines whether the input voltage signal is in a preset voltage threshold upper and lower bound, so as to determine whether the insulation resistance is good. The device directly determines whether the present insulation resistance satisfies safety requirements through outputting logic level by a hardware circuit, thereby improving detection speed and reducing cost.

Description

A kind of direct-current power ground insulation impedance detection apparatus and method
Technical field
The present invention relates to insulation impedance detection technique field, particularly relate to a kind of direct-current power ground insulation impedance detection apparatus and method.
Background technology
Bad or the resistance of direct supply (as electric powered motor accumulator, photovoltaic array etc.) ground insulation resistance is lower than setting, direct supply will be made to form high pressure over the ground, and then make the outer casing electrification of equipment of this direct supply of application, not only fragile equipment, returns personal safety and brings grave danger.Therefore, be necessary to detect direct-current power ground insulation impedance, to take corresponding regulation measure in time, ensure that insulation impedance meets regulation requirement all the time.Prior art is generally by the detection method of bridge balance principle, direct supply both positive and negative polarity over the ground between all in parallel given resistance value, a resistance bridge is formed with the both positive and negative polarity resistance to earth of direct supply, calculate current direct supply both positive and negative polarity resistance to earth in conjunction with direct supply both positive and negative polarity maximum voltage value by microprocessor software by the magnitude of voltage of ADC digital to analog converter sampling brachium pontis, then by and standard criterion in the insulation impedance value that specifies compare and judge whether current direct supply both positive and negative polarity ground insulation resistance good.
China Patent Publication No. CN102279317, publication date on Dec 14th, 2011, the name of invention is called the insulation against ground resistance online test method of photovoltaic combining inverter, this application case discloses a kind of insulation against ground resistance online test method of photovoltaic combining inverter, and it is by the output voltage V of sampling photovoltaic cell pVand by making the switch S 1 in resistance switch circuit be in disconnection or closure state, resistance R5 is departed from from upper brachium pontis or accesses in brachium pontis, then the voltage signal of the dividing potential drop output terminal of the lower brachium pontis of sampling, with the positive pole obtaining two groups of photovoltaic cells over the ground with the negative pole voltage ratio equation over the ground of photovoltaic cell, thus calculate positive pole insulation resistance R+ over the ground and the negative pole insulation resistance R-over the ground of photovoltaic cell of photovoltaic cell online real-time and accurately.Its weak point is, the method calculates current insulation impedance numerical value to signal voltage after multiple repairing weld, calculated amount is large and numerous and diverse, corresponding hardware resource cost is large, need the resistance being changed electric bridge brachium pontis by switch, and simulating signal converted to by ADC analog-digital converter part digital signal that microcomputer (microprocessor or DSP) can process and calculate the resistance of insulation impedance, standard comparing could judge that whether current state of insulation is good according to the rules again, if processor process figure place is low, the words that dominant frequency is not high, computing speed can be very slow.
Summary of the invention
The object of the invention is to overcome existing direct-current power ground insulation impedance detection apparatus structure complicated, the resistance of insulation impedance is calculated by microprocessor, calculate numerous and diverse, the technical matters that detection speed is slow, provide a kind of direct-current power ground insulation impedance detection apparatus and method, it directly realizes by hardware circuit output logic level the judgement whether current insulation impedance being met to safety code requirements, without the need to being calculated current insulation impedance numerical value by microprocessor software, improve detection speed, reduce cost.
In order to solve the problem, the present invention is achieved by the following technical solutions:
A kind of direct-current power ground insulation impedance detection device of the present invention, comprise resistance bridge circuit, voltage sampling circuit, filter amplification circuit, analog signal isolating module and threshold value comparator circuit, described resistance bridge circuit comprises resistance R3, resistance R4, resistance R5 and resistance R6, described resistance R3 one end is connected with the positive pole of direct supply, the described resistance R3 other end is connected with resistance R4 one end, described resistance R4 other end ground connection, described resistance R5 one end ground connection, the described resistance R5 other end is connected with the input end of voltage sampling circuit with resistance R6 one end, the described resistance R6 other end is connected with the negative pole of direct supply, the output terminal of described voltage sampling circuit is connected with the input end of filter amplification circuit, the output terminal of described filter amplification circuit is connected with the input end of analog signal isolating module, the output terminal of described analog signal isolating module is connected with the input end of threshold value comparator circuit, the output terminal output logic level of described threshold value comparator circuit.
In the technical program, between DC power anode and ground wire, there is insulation impedance R1, between DC power cathode and ground wire, have insulation impedance R2.During detection, direct supply both positive and negative polarity earth impedance is transformed into magnitude of voltage by resistance bridge circuit, wherein the bleeder circuit output voltage V of resistance R5 and resistance R6 o, shunting voltage V owith direct supply both positive and negative polarity ceiling voltage V maxbetween relation as formula: R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O , Therefore by gathering the voltage V of resistance R5 and the output of resistance R6 bleeder circuit ojust can reflect the change of direct supply both positive and negative polarity ground insulation resistance.
Voltage sampling circuit gathers the voltage signal V that resistance bridge circuit exports o, and outputted to filter amplification circuit.Filter amplification circuit first carries out power frequency and high-frequency harmonic filtering (mainly through low-pass filter filtering power frequency and high-frequency harmonic composition) to voltage signal, then analog voltage signal conditioning is amplified to the voltage standard (being completed by operational amplification circuit) of coupling rear class threshold value comparator circuit.Sampled voltage simulating signal through amplifying is carried out signal isolation, to improve the stability of signal by analog signal isolating module.
The voltage signal that analog signal isolating module exports by threshold value comparator circuit and voltage threshold bound compare, if voltage signal is within the scope of voltage threshold bound, then threshold value comparator circuit exports high level, otherwise threshold value comparator circuit output low level.This logic level signal is the standard judging that whether current direct supply both positive and negative polarity ground insulation resistance is good, and high level represents that insulation impedance is in good condition, and low level represents that insulation impedance goes wrong, and does not meet the requirement of security regulations.
Order λ = R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) , η = R 5 + R 6 R 6 , Formula R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O Be converted to V O = V max ( λ + 1 ) * η , Normal range according to security regulations standard determination DC power anode ground insulation resistance R1 is R1>=R 1min, the normal range of DC power cathode ground insulation resistance R2 is R2>=R 2min, thus determine the scope (λ of λ min, λ max), thus calculate V oscope (V omin, V omax), (V omin, V omax) be multiplied by the amplification coefficient of filter amplification circuit after the range of voltage values that obtains be voltage threshold bound scope as criterion in threshold value comparator circuit.
As preferably, described threshold value comparator circuit comprises the first stabilized voltage supply, resistance R7, resistance R8, resistance R9, resistance R10, resistance R11, resistance R12, resistance R13, resistance R14, operational amplifier U1 and operational amplifier U2, the input end in the same way of described operational amplifier U1 and resistance R7 one end, resistance R9 one end is connected with resistance R10 one end, the resistance R7 other end is connected with the positive pole of the first stabilized voltage supply, the resistance R9 other end is connected with the output terminal of operational amplifier U1, resistance R10 other end ground connection, the reverse input end of described operational amplifier U1 is connected with resistance R8 one end, the resistance R8 other end is connected with the output terminal of analog signal isolating module with resistance R11 one end, the resistance R11 other end is connected with the input end in the same way of operational amplifier U2 with resistance R13 one end, the resistance R13 other end is connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R14 one end with resistance R12 one end, the resistance R12 other end is connected with the positive pole of the first stabilized voltage supply, resistance R14 other end ground connection, the output terminal of described operational amplifier U1 is connected with the output terminal of operational amplifier U2, the output terminal of operational amplifier U1 is the output terminal of threshold value comparator circuit.
Resistance R7, resistance R8, resistance R9, resistance R10 and operational amplifier U1 form upper voltage limit threshold value comparator circuit, and resistance R11, resistance R12, resistance R13, resistance R14 and operational amplifier U2 form lower voltage limit threshold value comparator circuit.Its Output rusults is also low level time together with high level signal accesses with low level signal and after low and high level and logical operation, so operational amplifier U1 and any one output low level of operational amplifier U2, and threshold value comparator circuit output low level.
As preferably, described a kind of direct-current power ground insulation impedance detection device also comprises clamping circuit, described clamping circuit comprises the second stabilized voltage supply, diode D1 and diode D2, the output terminal of described threshold value comparator circuit is connected with the negative electrode of diode D2 with the anode of diode D1, the negative electrode of described diode D1 is connected with the positive pole of the second stabilized voltage supply, the plus earth of described diode D2.The logic level that threshold value comparator circuit exports will be nursed one's health into the voltage range after clamper, so that the devices function such as driving switch pipe or relay controls the break-make of direct supply through diode D1 its logic-level voltages standard after diode D2 clamper limit volt.
As preferably, described analog signal isolating module is linear optical coupling.
As preferably, described a kind of direct-current power ground insulation impedance detection device also comprises switch actuator part, described switch actuator part and direct supply become a loop with load in series, the control end of described switch actuator part is connected with the output terminal of threshold value comparator circuit.When threshold value comparator circuit exports high level, switch actuator part closes, and connects direct supply; When threshold value comparator circuit output low level, switch actuator part disconnects, and disconnects direct supply.
As preferably, described a kind of direct-current power ground insulation impedance detection device also comprises warning circuit, and described warning circuit is connected with the output terminal of threshold value comparator circuit.When threshold value comparator circuit output low level, warning circuit sends warning.
A kind of direct-current power ground insulation impedance detection method of the present invention, comprises the following steps:
S1: obtained the voltage signal be associated with direct supply both positive and negative polarity ground insulation resistance by resistance bridge circuit;
S2: the voltage signal that voltage sampling circuit sampling resistor bridge diagram exports, and outputted to filter amplification circuit;
S3: filter amplification circuit outputs to analog signal isolating module after carrying out filter and amplification to voltage signal;
S4: voltage signal inputs threshold value comparator circuit after the isolation of analog signal isolating module;
S5: input voltage signal and upper voltage limit threshold value and lower voltage limit threshold value compare by threshold value comparator circuit, when input voltage signal is between upper voltage limit threshold value and lower voltage limit threshold value, threshold value comparator circuit exports high level, when input voltage signal is greater than upper voltage limit threshold value or is less than lower voltage limit threshold value, threshold value comparator circuit output low level;
S6: the level signal that threshold value comparator circuit exports exports after clamping circuit clamper, if the level signal exported is that high level represents that insulation impedance is in good condition, if the level signal exported is that low level represents that insulation impedance goes wrong.
As preferably, the setting of described upper voltage limit threshold value and lower voltage limit threshold value comprises the following steps: the normal range according to security regulations standard determination DC power anode ground insulation resistance R1 is R1>=R 1min, the normal range of DC power cathode ground insulation resistance R2 is R2>=R 2min, obtain formula according to resistance bridge circuit: R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O , Wherein, V maxfor the voltage between direct supply both positive and negative polarity, V ofor the voltage that voltage sampling circuit collects,
Order λ = R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) , η = R 5 + R 6 R 6 , Calculate V O = V max ( λ + 1 ) * η , According to R1>=R 1minwith R2>=R 2mindetermine the scope (λ of λ min, λ max), thus calculate V oscope (V omin, V omax), (V omin, V omax) be multiplied by the amplification coefficient of filter amplification circuit after the maximum voltage value that obtains and minimum amount of voltage that respectively as upper voltage limit threshold value and lower voltage limit threshold value.
Substantial effect of the present invention is: directly realize by hardware circuit output logic level the judgement whether current insulation impedance being met to safety code requirements, without the need to being calculated current insulation impedance numerical value by microprocessor software, improve detection speed, reduce cost.
Accompanying drawing explanation
Fig. 1 is that a kind of circuit theory of the present invention connects block diagram;
Fig. 2 is the circuit theory diagrams of resistance bridge circuit;
Fig. 3 is the circuit theory diagrams of threshold value comparator circuit and clamping circuit.
In figure: 1, resistance bridge circuit, 2, voltage sampling circuit, 3, filter amplification circuit, 4, analog signal isolating module, 5, threshold value comparator circuit, 6, direct supply, 7, clamping circuit, 8, switch actuator part, 9, warning circuit.
Embodiment
Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is described in further detail.
Embodiment: a kind of direct-current power ground insulation impedance detection device of the present invention, as shown in Figure 1, comprise resistance bridge circuit 1, voltage sampling circuit 2, filter amplification circuit 3, analog signal isolating module 4, threshold value comparator circuit 5, clamping circuit 7, switch actuator part 8 and warning circuit 9, as shown in Figure 2, resistance bridge circuit 1 comprises resistance R3, resistance R4, resistance R5 and resistance R6, resistance R3 one end is connected with the positive pole of direct supply 6, the resistance R3 other end is connected with resistance R4 one end, resistance R4 other end ground connection, resistance R5 one end ground connection, the resistance R5 other end is connected with the input end of voltage sampling circuit 2 with resistance R6 one end, the resistance R6 other end is connected with the negative pole of direct supply 6, the output terminal of voltage sampling circuit 2 is connected with the input end of filter amplification circuit 3, the output terminal of filter amplification circuit 3 is connected with the input end of analog signal isolating module 4, the output terminal of analog signal isolating module 4 is connected with the input end of threshold value comparator circuit 5, as shown in Figure 3, threshold value comparator circuit 5 comprises the first stabilized voltage supply, resistance R7, resistance R8, resistance R9, resistance R10, resistance R11, resistance R12, resistance R13, resistance R14, operational amplifier U1 and operational amplifier U2, the input end in the same way of operational amplifier U1 and resistance R7 one end, resistance R9 one end is connected with resistance R10 one end, the resistance R7 other end is connected with the positive pole of the first stabilized voltage supply, the resistance R9 other end is connected with the output terminal of operational amplifier U1, resistance R10 other end ground connection, the reverse input end of operational amplifier U1 is connected with resistance R8 one end, the resistance R8 other end is connected with the output terminal of analog signal isolating module 4 with resistance R11 one end, the resistance R11 other end is connected with the input end in the same way of operational amplifier U2 with resistance R13 one end, the resistance R13 other end is connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R14 one end with resistance R12 one end, the resistance R12 other end is connected with the positive pole of the first stabilized voltage supply, resistance R14 other end ground connection, the output terminal of operational amplifier U1 is connected with the output terminal of operational amplifier U2, the output terminal of operational amplifier U1 is the output terminal of threshold value comparator circuit 5, first stabilized voltage supply is 15V direct supply.Clamping circuit 7 comprises the second stabilized voltage supply, diode D1 and diode D2, the output terminal of threshold value comparator circuit 5 is connected with the negative electrode of diode D2 with the anode of diode D1, the negative electrode of diode D1 is connected with the positive pole of the second stabilized voltage supply, the plus earth of diode D2, the second stabilized voltage supply is 3.3V direct supply.The output terminal of threshold value comparator circuit 5 is also connected with warning circuit 9 with the control end of switch actuator part 8, and switch actuator part 8 and direct supply 6 become a loop with load in series.
There is insulation impedance R1 between direct supply 6 positive pole and ground wire, between direct supply 6 negative pole and ground wire, have insulation impedance R2.During detection, direct supply 6 both positive and negative polarity earth impedance is transformed into magnitude of voltage by resistance bridge circuit 1, wherein the bleeder circuit output voltage V of resistance R5 and resistance R6 o, shunting voltage V owith direct supply 6 both positive and negative polarity ceiling voltage V maxbetween relation as formula: R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O , Therefore by gathering the voltage V of resistance R5 and the output of resistance R6 bleeder circuit ojust can reflect the change of direct supply 6 both positive and negative polarity ground insulation resistance.
Voltage sampling circuit 2 gathers the voltage signal V that resistance bridge circuit 1 exports o, and outputted to filter amplification circuit 3.Filter amplification circuit 3 first carries out power frequency and high-frequency harmonic filtering (mainly through low-pass filter filtering power frequency and high-frequency harmonic composition) to voltage signal, then analog voltage signal conditioning is amplified to the voltage standard (being completed by operational amplification circuit) of coupling rear class threshold value comparator circuit.Sampled voltage simulating signal through amplifying is carried out signal isolation by analog signal isolating module 4, and to improve the stability of signal, analog signal isolating module 4 is linear optical coupling.
The voltage signal that analog signal isolating module 4 exports by threshold value comparator circuit 5 and voltage threshold bound compare, if voltage signal is within the scope of voltage threshold bound, then threshold value comparator circuit 5 exports high level, otherwise threshold value comparator circuit 5 output low level.This logic level signal is the standard judging that whether current direct supply 6 both positive and negative polarity ground insulation resistance is good, and high level represents that insulation impedance is in good condition, and low level represents that insulation impedance goes wrong, and does not meet the requirement of security regulations.
Resistance R7, resistance R8, resistance R9, resistance R10 and operational amplifier U1 form upper voltage limit threshold value comparator circuit, and resistance R11, resistance R12, resistance R13, resistance R14 and operational amplifier U2 form lower voltage limit threshold value comparator circuit.Its Output rusults is also low level time together with high level signal accesses with low level signal and after low and high level and logical operation, so operational amplifier U1 and any one output low level of operational amplifier U2, and threshold value comparator circuit output low level.
Order λ = R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) , η = R 5 + R 6 R 6 , Formula R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O Be converted to V O = V max ( λ + 1 ) * η , Normal range according to security regulations standard determination direct supply 6 positive pole ground insulation resistance R1 is R1>=R 1min, the normal range of direct supply 6 negative pole ground insulation resistance R2 is R2>=R 2min, thus determine the scope (λ of λ min, λ max), thus calculate V oscope (V omin, V omax), (V omin, V omax) be multiplied by the amplification coefficient of filter amplification circuit 3 after the range of voltage values that obtains be voltage threshold bound scope as criterion in threshold value comparator circuit 5.The input voltage value of the input end in the same way of operational amplifier U1 equals upper voltage limit threshold value, and the input voltage value of the reverse input end of operational amplifier U2 equals lower voltage limit threshold value.
The logic level that threshold value comparator circuit 5 exports will be nursed one's health into the voltage range after clamper through diode D1 its logic-level voltages standard after diode D2 clamper limit volt.The level signal that threshold value comparator circuit 5 exports outputs to control end and the warning circuit 9 of switch actuator part 8 after clamping circuit clamper, and when clamping circuit 7 exports high level, switch actuator part 8 closes, and connects direct supply 6; When clamping circuit 7 output low level, switch actuator part 8 disconnects, and disconnect direct supply 6, warning circuit 9 sends warning.
A kind of direct-current power ground insulation impedance detection method of the present invention, is applicable to above-mentioned direct-current power ground insulation impedance detection device, comprises the following steps:
S1: obtained the voltage signal V be associated with direct supply 6 both positive and negative polarity ground insulation resistance by resistance bridge circuit 1 o;
S2: the voltage signal V that voltage sampling circuit 2 sampling resistor bridge diagram 1 exports o, and outputted to filter amplification circuit 3;
S3: filter amplification circuit 3 couples of voltage signal V oanalog signal isolating module 4 is outputted to after carrying out filter and amplification;
S4: voltage signal inputs threshold value comparator circuit 5 after analog signal isolating module 4 is isolated;
S5: input voltage signal and upper voltage limit threshold value and lower voltage limit threshold value compare by threshold value comparator circuit 5, when input voltage signal is less than or equal to upper voltage limit threshold value and is more than or equal between lower voltage limit threshold value, threshold value comparator circuit 5 exports high level, when input voltage signal is greater than upper voltage limit threshold value or is less than lower voltage limit threshold value, threshold value comparator circuit 5 output low level;
S6: the level signal that threshold value comparator circuit 5 exports outputs to control end and the warning circuit 9 of switch actuator part 8 after clamping circuit 7 clamper, when clamping circuit 7 exports high level, represent that insulation impedance is in good condition, switch actuator part 8 closes, and connects direct supply 6; When clamping circuit 7 output low level, represent that insulation impedance goes wrong, switch actuator part 8 disconnects, and disconnect direct supply 6, warning circuit 9 sends warning.
The setting of upper voltage limit threshold value and lower voltage limit threshold value comprises the following steps: the normal range according to security regulations standard determination direct supply 6 positive pole ground insulation resistance R1 is R1>=R 1min, the normal range of direct supply 6 negative pole ground insulation resistance R2 is R2>=R 2min, obtain formula according to resistance bridge circuit 1: R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O , Wherein, V maxfor the voltage between direct supply 6 both positive and negative polarity, V ofor the voltage that voltage sampling circuit 2 collects,
Order λ = R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) , η = R 5 + R 6 R 6 , Calculate V O = V max ( λ + 1 ) * η , According to R1>=R 1minwith R2>=R 2mindetermine the scope (λ of λ min, λ max), thus calculate V oscope (V omin, V omax), (V omin, V omax) be multiplied by the amplification coefficient of filter amplification circuit 3 after the maximum voltage value that obtains and minimum amount of voltage that respectively as upper voltage limit threshold value and lower voltage limit threshold value.

Claims (8)

1. a direct-current power ground insulation impedance detection device, it is characterized in that: comprise resistance bridge circuit (1), voltage sampling circuit (2), filter amplification circuit (3), analog signal isolating module (4) and threshold value comparator circuit (5), described resistance bridge circuit (1) comprises resistance R3, resistance R4, resistance R5 and resistance R6, described resistance R3 one end is connected with the positive pole of direct supply (6), the described resistance R3 other end is connected with resistance R4 one end, described resistance R4 other end ground connection, described resistance R5 one end ground connection, the described resistance R5 other end is connected with the input end of resistance R6 one end with voltage sampling circuit (2), the described resistance R6 other end is connected with the negative pole of direct supply (6), the output terminal of described voltage sampling circuit (2) is connected with the input end of filter amplification circuit (3), the output terminal of described filter amplification circuit (3) is connected with the input end of analog signal isolating module (4), the output terminal of described analog signal isolating module (4) is connected with the input end of threshold value comparator circuit (5), the output terminal output logic level of described threshold value comparator circuit (5).
2. a kind of direct-current power ground insulation impedance detection device according to claim 1, it is characterized in that: described threshold value comparator circuit (5) comprises the first stabilized voltage supply, resistance R7, resistance R8, resistance R9, resistance R10, resistance R11, resistance R12, resistance R13, resistance R14, operational amplifier U1 and operational amplifier U2, the input end in the same way of described operational amplifier U1 and resistance R7 one end, resistance R9 one end is connected with resistance R10 one end, the resistance R7 other end is connected with the positive pole of the first stabilized voltage supply, the resistance R9 other end is connected with the output terminal of operational amplifier U1, resistance R10 other end ground connection, the reverse input end of described operational amplifier U1 is connected with resistance R8 one end, the resistance R8 other end is connected with the output terminal of resistance R11 one end with analog signal isolating module (4), the resistance R11 other end is connected with the input end in the same way of operational amplifier U2 with resistance R13 one end, the resistance R13 other end is connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R14 one end with resistance R12 one end, the resistance R12 other end is connected with the positive pole of the first stabilized voltage supply, resistance R14 other end ground connection, the output terminal of described operational amplifier U1 is connected with the output terminal of operational amplifier U2, the output terminal of operational amplifier U1 is the output terminal of threshold value comparator circuit (5).
3. a kind of direct-current power ground insulation impedance detection device according to claim 1, it is characterized in that: also comprise clamping circuit (7), described clamping circuit (7) comprises the second stabilized voltage supply, diode D1 and diode D2, the described output terminal of threshold value comparator circuit (5) is connected with the negative electrode of diode D2 with the anode of diode D1, the negative electrode of described diode D1 is connected with the positive pole of the second stabilized voltage supply, the plus earth of described diode D2.
4. a kind of direct-current power ground insulation impedance detection device according to claim 1 or 2 or 3, is characterized in that: described analog signal isolating module (4) is linear optical coupling.
5. a kind of direct-current power ground insulation impedance detection device according to claim 1 or 2 or 3, it is characterized in that: also comprise switch actuator part (8), described switch actuator part (8) becomes a loop with direct supply (6) with load in series, and the control end of described switch actuator part (8) is connected with the output terminal of threshold value comparator circuit (5).
6. a kind of direct-current power ground insulation impedance detection device according to claim 1 or 2 or 3, it is characterized in that: also comprise warning circuit (9), described warning circuit (9) is connected with the output terminal of threshold value comparator circuit (5).
7. a direct-current power ground insulation impedance detection method, is applicable to a kind of direct-current power ground insulation impedance detection device as described in claim any in claim 1-6, it is characterized in that comprising the following steps:
S1: obtained the voltage signal be associated with direct supply both positive and negative polarity ground insulation resistance by resistance bridge circuit;
S2: the voltage signal that voltage sampling circuit sampling resistor bridge diagram exports, and outputted to filter amplification circuit;
S3: filter amplification circuit outputs to analog signal isolating module after carrying out filter and amplification to voltage signal;
S4: voltage signal inputs threshold value comparator circuit after the isolation of analog signal isolating module;
S5: input voltage signal and upper voltage limit threshold value and lower voltage limit threshold value compare by threshold value comparator circuit, when input voltage signal is between upper voltage limit threshold value and lower voltage limit threshold value, threshold value comparator circuit exports high level, when input voltage signal is greater than upper voltage limit threshold value or is less than lower voltage limit threshold value, threshold value comparator circuit output low level;
S6: the level signal that threshold value comparator circuit exports exports after clamping circuit clamper, if the level signal exported is that high level represents that insulation impedance is in good condition, if the level signal exported is that low level represents that insulation impedance goes wrong.
8. a kind of direct-current power ground insulation impedance detection method according to claim 7, it is characterized in that, the setting of described upper voltage limit threshold value and lower voltage limit threshold value comprises the following steps: the normal range according to security regulations standard determination DC power anode ground insulation resistance R1 is R1>=R 1min, the normal range of DC power cathode ground insulation resistance R2 is R2>=R 2min, obtain formula according to resistance bridge circuit:
R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) = V max - ( R 5 + R 6 R 6 ) V O ( R 5 + R 6 R 6 ) V O , Wherein, V maxfor the voltage between direct supply both positive and negative polarity, V ofor the voltage that voltage sampling circuit collects,
Order λ = R 1 / / ( R 3 + R 4 ) R 2 / / ( R 5 + R 6 ) , η = R 5 + R 6 R 6 , Calculate V O = V max ( λ + 1 ) * η , According to R1>=R lminwith R2>=R 2mindetermine the scope (λ of λ min, λ max), thus calculate V oscope (V omin, V omax), (V omii, V omax) be multiplied by the amplification coefficient of filter amplification circuit after the maximum voltage value that obtains and minimum amount of voltage that respectively as upper voltage limit threshold value and lower voltage limit threshold value.
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Cited By (9)

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CN106093586A (en) * 2016-08-17 2016-11-09 苏州爱康能源工程技术股份有限公司 Photovoltaic combiner box insulation resistance of DC system detecting system and detection method thereof
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CN112986777A (en) * 2019-12-12 2021-06-18 中国科学院沈阳自动化研究所 General type underwater robot power supply system insulation detection device
CN113433380A (en) * 2021-06-24 2021-09-24 深圳市白光电子科技有限公司 Voltage sampling control method and device
CN113433380B (en) * 2021-06-24 2023-09-05 深圳市白光电子科技有限公司 Voltage sampling control method and device

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