CN203465354U - Detection device of DC power supply insulation resistance to ground - Google Patents

Abstract

The utility model discloses a detection device of a DC power supply insulation resistance to ground. The detection device comprises a resistance bridge circuit, a voltage sampling circuit, a filter amplifying circuit, an analog signal isolation module and a threshold comparison circuit. A DC power supply is connected with the resistance bridge circuit, an output end of the resistance bridge circuit is connected with an input end of the voltage sampling circuit, an output end of the voltage sampling circuit is connected with an input end of the filter amplifying circuit, an output end of the filter amplifying circuit is connected with an input end of the analog signal isolation module, an output end of the analog signal isolation module is connected with an input end of the threshold comparison circuit, and an output end of the threshold comparison circuit outputs a logic level. The logic level is directly output through a hardware circuit to allow a judgment that whether a current insulation resistance satisfies safety regulation requirements to be achieved, a microprocessor software is not needed to calculate a current insulation resistance value, a detection speed is improved, and cost is reduced.

Description

A kind of direct supply insulation against ground impedance detection device

Technical field

The utility model relates to insulation impedance detection technique field, relates in particular to a kind of direct supply insulation against ground impedance detection device.

Background technology

Bad or the resistance of direct supply (as electric powered motor accumulator, photovoltaic array etc.) insulation against ground impedance is lower than setting, to make direct supply form over the ground high pressure, and then make to apply the outer casing electrification of the equipment of this direct supply, not only fragile equipment, returns personal safety and brings grave danger.Therefore, be necessary direct supply insulation against ground impedance to detect, to take in time to regulate accordingly measure, guarantee that insulation impedance meets regulation requirement all the time.Prior art scheme is generally by the detection method of bridge balance principle, direct supply both positive and negative polarity over the ground between equal in parallel given resistance values, form a resistance bridge with the both positive and negative polarity resistance to earth of direct supply, magnitude of voltage by ADC digital to analog converter sampling brachium pontis calculates current direct supply both positive and negative polarity resistance to earth in conjunction with direct supply both positive and negative polarity maximum voltage value and by microprocessor software, then by with standard criterion in the insulation impedance value stipulated compare and judge that whether current direct supply both positive and negative polarity insulation against ground impedance good.

China Patent Publication No. CN102279317, open day 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 switch S 1 in resistance switch circuit in disconnecting or closure state, resistance R 5 is departed from from upper brachium pontis or access in brachium pontis, then the voltage signal of the dividing potential drop output terminal of brachium pontis under sampling, with the positive pole that obtains two groups of photovoltaic cells over the ground with the negative pole of photovoltaic cell voltage ratio equation over the ground, thereby the negative pole of insulation resistance R+ over the ground of the positive pole that calculates real-time and accurately online photovoltaic cell and photovoltaic cell insulation resistance R-over the ground.Its weak point is, the structure of the detecting device complexity that the method is corresponding, need to change by switch the resistance of electric bridge brachium pontis, and convert simulating signal to the digital signal that microcomputer (microprocessor or DSP) can process the resistance that calculates insulation impedance by ADC analog-digital converter part, standard relatively could judge that whether current state of insulation is good according to the rules again, if processor is processed, figure place is low, and dominant frequency is not high, and computing speed can be very slow.

Summary of the invention

The purpose of this utility model is to overcome existing direct supply insulation against ground impedance detection apparatus structure complexity, by microprocessor, calculate the resistance of insulation impedance, calculate numerous and diverse, the technical matters that detection speed is slow, a kind of direct supply insulation against ground impedance detection device is provided, it directly realizes by hardware circuit output logic level whether current insulation impedance is met to the judgement that security regulations require, without calculate current insulation impedance numerical value by microprocessor software, improve detection speed, reduced cost.

In order to address the above problem, the utility model is achieved by the following technical solutions:

A kind of direct supply insulation against ground impedance detection device of the present utility model, comprise resistance bridge circuit, voltage sampling circuit, filter amplification circuit, simulating signal isolation module and threshold value comparator circuit, described resistance bridge circuit comprises resistance R 3, resistance R 4, resistance R 5 and resistance R 6, described resistance R 3 one end are connected with the positive pole of direct supply, described resistance R 3 other ends are connected with resistance R 4 one end, described resistance R 4 other end ground connection, described resistance R 5 one end ground connection, described resistance R 5 other ends are connected with the input end of resistance R 6 one end and voltage sampling circuit, described resistance R 6 other ends are 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 simulating signal isolation module, the output terminal of described simulating signal isolation 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, there is insulation impedance R2.During detection, resistance bridge circuit is transformed into magnitude of voltage by direct supply both positive and negative polarity earth impedance, wherein the bleeder circuit output voltage V of resistance R 5 and resistance R 6_o, shunting voltage V_owith direct supply both positive and negative polarity ceiling voltage V_maxbetween relation as formula:$\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)}=\frac{V_{\max }-\left(\frac{R5+R6}{R6}\right)V_O}{\left(\frac{R5+R6}{R6}\right)V_O},$Therefore by gathering the voltage V of resistance R 5 and resistance R 6 bleeder circuit outputs_ojust can reflect the variation of direct supply both positive and negative polarity insulation against ground impedance.

Voltage sampling circuit gathers the voltage signal V of resistance bridge circuit output_o, and outputed to filter amplification circuit.Filter amplification circuit is first carried out power frequency and high-frequency harmonic filtering (mainly by 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 (completing by operational amplification circuit) of coupling rear class threshold value comparator circuit.Simulating signal isolation module is by carrying out signal isolation through the sampled voltage simulating signal of amplifying, to improve the stability of signal.

Threshold value comparator circuit compares voltage signal and the voltage threshold bound of simulating signal isolation module output, if voltage signal within the scope of voltage threshold bound, threshold value comparator circuit is exported high level, otherwise threshold value comparator circuit output low level.This logic level signal is for to judge that the whether good standard of current direct supply both positive and negative polarity insulation against ground impedance, high level represent 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$\mathrm{\&lambda;}=\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)},\mathrm{\&eta;}=\frac{R5+R6}{R6},$Formula$\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)}=\frac{V_{\max }-\left(\frac{R5+R6}{R6}\right)V_O}{\left(\frac{R5+R6}{R6}\right)V_O}$Be converted to$V_O=\frac{V_{\max }}{(\mathrm{\&lambda;}+1)*\mathrm{\&eta;}},$According to the normal range of security regulations standard DC power anode insulation against ground impedance R1, be R1>=R_1min, the normal range of DC power cathode insulation against ground impedance R2 is R2>=R_2minthereby, the scope (λ of definite λ_min, λ_max), thereby calculate V_oscope (V_omin, V_omax), (V_omin, V_omax) to be multiplied by the range of voltage values obtaining after the amplification coefficient of filter amplification circuit be as the voltage threshold bound scope of criterion in threshold value comparator circuit.

As preferably, described threshold value comparator circuit comprises the first stabilized voltage supply,resistance R 7, resistance R 8,resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, resistance R 14, operational amplifier U1 and operational amplifier U2, the input end in the same way of described operational amplifier U1 andresistance R 7 one end,resistance R 9 one end are connected with resistance R 10 one end,resistance R 7 other ends are connected with the positive pole of the first stabilized voltage supply,resistance R 9 other ends are connected with the output terminal of operational amplifier U1, resistance R 10 other end ground connection, the reverse input end of described operational amplifier U1 is connected with resistance R 8 one end, resistance R 8 other ends are connected with the output terminal of simulating signal isolation module with resistance R 11 one end, resistance R 11 other ends are connected with the input end in the same way of resistance R 13 one end and operational amplifier U2, resistance R 13 other ends are connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R 14 one end with resistance R 12 one end, resistance R 12 other ends are connected with the positive pole of the first stabilized voltage supply, resistance R 14 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 R 7, resistance R 8,resistance R 9, resistance R 10 and operational amplifier U1 form upper voltage limit threshold value comparator circuit, and resistance R 11, resistance R 12, resistance R 13, resistance R 14 and operational amplifier U2 form lower voltage limit threshold value comparator circuit.In the time of together with high level signal accesses with low level signal, after low and high level and logical operation, its Output rusults is also low level, thus operational amplifier U1 and any one output low level of operational amplifier U2, threshold value comparator circuit output low level.

As preferably, described a kind of direct supply insulation against ground 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.After the logic level of threshold value comparator circuit output lies prostrate with diode D2 clamper limit through diode D1, its logic-level voltages standard is by the voltage range of being nursed one's health into after clamper, so that the break-make of the device job control direct supplys such as driving switch pipe or relay.

As preferably, described simulating signal isolation module is linear optical coupling.

As preferably, described a kind of direct supply insulation against ground impedance detection device also comprises switch actuator part, described switch actuator part and direct supply and load are connected into a loop, and the control end of described switch actuator part is connected with the output terminal of threshold value comparator circuit.When threshold value comparator circuit output high level, switch actuator part is closed, 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 supply insulation against ground 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.

Essence effect of the present utility model is: directly by hardware circuit output logic level, realize whether current insulation impedance is met to the judgement that security regulations require, without calculate current insulation impedance numerical value by microprocessor software, improve detection speed, reduced cost.

Accompanying drawing explanation

Fig. 1 is that a kind of circuit theory of the present utility model 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, simulating signal isolation 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, the technical solution of the utility model is described in further detail.

Embodiment: a kind of direct supply insulation against ground impedance detection device of the present utility model, as shown in Figure 1, comprise resistance bridge circuit 1,voltage sampling circuit 2, filter amplification circuit 3, simulating signal isolation module 4, threshold value comparator circuit 5,clamping circuit 7, switch actuator part 8 andwarning circuit 9, as shown in Figure 2, resistance bridge circuit 1 comprises resistance R 3, resistance R 4, resistance R 5 and resistance R 6, resistance R 3 one end are connected with the positive pole of direct supply 6, resistance R 3 other ends are connected with resistance R 4 one end, resistance R 4 other end ground connection, resistance R 5 one end ground connection, resistance R 5 other ends are connected with the input end ofvoltage sampling circuit 2 with resistance R 6 one end, resistance R 6 other ends are connected with the negative pole of direct supply 6, the output terminal ofvoltage 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 simulating signal isolation module 4, the output terminal of simulating signal isolation 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 R 7, resistance R 8,resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, resistance R 14, operational amplifier U1 and operational amplifier U2, the input end in the same way of operational amplifier U1 andresistance R 7 one end,resistance R 9 one end are connected with resistance R 10 one end,resistance R 7 other ends are connected with the positive pole of the first stabilized voltage supply,resistance R 9 other ends are connected with the output terminal of operational amplifier U1, resistance R 10 other end ground connection, the reverse input end of operational amplifier U1 is connected with resistance R 8 one end, resistance R 8 other ends are connected with the output terminal of simulating signal isolation module 4 with resistance R 11 one end, resistance R 11 other ends are connected with the input end in the same way of resistance R 13 one end and operational amplifier U2, resistance R 13 other ends are connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R 14 one end with resistance R 12 one end, resistance R 12 other ends are connected with the positive pole of the first stabilized voltage supply, resistance R 14 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, the first stabilized voltage supply is 15V directsupply.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 withwarning circuit 9 with the control end of switch actuator part 8, and switch actuator part 8 is connected into a loop with direct supply 6 and load.

Between direct supply 6 positive poles and ground wire, there is insulation impedance R1, between direct supply 6 negative poles and ground wire, have insulation impedance R2.During detection, resistance bridge circuit 1 is transformed into magnitude of voltage by direct supply 6 both positive and negative polarity earth impedance, wherein the bleeder circuit output voltage V of resistance R 5 and resistance R 6_o, shunting voltage V_owith direct supply 6 both positive and negative polarity ceiling voltage V_maxbetween relation as formula:$\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)}=\frac{V_{\max }-\left(\frac{R5+R6}{R6}\right)V_o}{\left(\frac{R5+R6}{R6}\right)V_o},$Therefore by gathering the voltage V of resistance R 5 and resistance R 6 bleeder circuit outputs_ojust can reflect the variation of direct supply 6 both positive and negative polarity insulation against ground impedances.

Voltage sampling circuit 2 gathers the voltage signal V of resistance bridge circuit 1 output_o, and outputed to filter amplification circuit 3.Filter amplification circuit 3 is first carried out power frequency and high-frequency harmonic filtering (mainly by 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 (completing by operational amplification circuit) of coupling rear class threshold value comparator circuit.Simulating signal isolation module 4 will carry out signal isolation through the sampled voltage simulating signal of amplifying, and to improve the stability of signal, simulating signal isolation module 4 is linear optical coupling.

Threshold value comparator circuit 5 compares voltage signal and the voltage threshold bound of 4 outputs of simulating signal isolation module, if voltage signal is within the scope of voltage threshold bound, threshold value comparator circuit 5 is exported high level, otherwise threshold value comparator circuit 5 output low levels.This logic level signal is for to judge that the whether good standard of current direct supply 6 both positive and negative polarity insulation against ground impedance, high level represent 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 R 7, resistance R 8,resistance R 9, resistance R 10 and operational amplifier U1 form upper voltage limit threshold value comparator circuit, and resistance R 11, resistance R 12, resistance R 13, resistance R 14 and operational amplifier U2 form lower voltage limit threshold value comparator circuit.In the time of together with high level signal accesses with low level signal, after low and high level and logical operation, its Output rusults is also low level, thus operational amplifier U1 and any one output low level of operational amplifier U2, threshold value comparator circuit output low level.

Order$\mathrm{\&lambda;}=\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)},$$\mathrm{\&eta;}=\frac{R5+R6}{R6},$Formula$\frac{R1//(R3+R4)}{\mathrm{<figure-callout\; label="R"\; filenames="HDA0000373773070000021.png"\; state="\{\{state\}\}">R</figure-callout>}2//(R5+R6)}=\frac{V_{\max }-\left(\frac{R5+R6}{R6}\right)V_o}{\left(\frac{R5+R6}{R6}\right)V_o}$Be converted to$V_o=\frac{V_{\max }}{(\mathrm{\&lambda;}+1)*\mathrm{\&eta;}},$According to the normal range of the anodal insulation against ground impedance R1 of security regulations standard direct supply 6, be R1>=R_1min, the normal range of direct supply 6 negative pole insulation against ground impedance R2 is R2>=R_2minthereby, the scope (λ of definite λ_min, λ_max), thereby calculate V_oscope (V_omin, V_omax), (V_omin, V_omax) to be multiplied by the range of voltage values obtaining after the amplification coefficient of filter amplification circuit 3 be as the voltage threshold bound scope of 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.

After the logic level of threshold value comparator circuit 5 outputs lies prostrate with diode D2 clamper limit through diode D1, its logic-level voltages standard is by the voltage range of being nursed one's health into after clamper.The level signal of threshold value comparator circuit 5 outputs outputs to control end and thewarning circuit 9 of switch actuator part 8 after clamping circuit clamper, and whenclamping circuit 7 output high level, switch actuator part 8 closures, connect direct supply 6; Whenclamping circuit 7 output low level, switch actuator part 8 disconnects, and disconnects direct supply 6, andwarning circuit 9 sends warning.

Claims (6)

1. a direct supply insulation against ground impedance detection device, it is characterized in that: comprise resistance bridge circuit (1), voltage sampling circuit (2), filter amplification circuit (3), simulating signal isolation module (4) and threshold value comparator circuit (5), described resistance bridge circuit (1) comprises resistance R 3, resistance R 4, resistance R 5 and resistance R 6, described resistance R 3 one end are connected with the positive pole of direct supply (6), described resistance R 3 other ends are connected with resistance R 4 one end, described resistance R 4 other end ground connection, described resistance R 5 one end ground connection, described resistance R 5 other ends are connected with the input end of voltage sampling circuit (2) with resistance R 6 one end, described resistance R 6 other ends are 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 simulating signal isolation module (4), the output terminal of described simulating signal isolation 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 supply insulation against ground 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 R 7, resistance R 8, resistance R 9, resistance R 10, resistance R 11, resistance R 12, resistance R 13, resistance R 14, operational amplifier U1 and operational amplifier U2, the input end in the same way of described operational amplifier U1 and resistance R 7 one end, resistance R 9 one end are connected with resistance R 10 one end, resistance R 7 other ends are connected with the positive pole of the first stabilized voltage supply, resistance R 9 other ends are connected with the output terminal of operational amplifier U1, resistance R 10 other end ground connection, the reverse input end of described operational amplifier U1 is connected with resistance R 8 one end, resistance R 8 other ends are connected with the output terminal of simulating signal isolation module (4) with resistance R 11 one end, resistance R 11 other ends are connected with the input end in the same way of resistance R 13 one end and operational amplifier U2, resistance R 13 other ends are connected with the output terminal of operational amplifier U2, the reverse input end of described operational amplifier U2 is connected with resistance R 14 one end with resistance R 12 one end, resistance R 12 other ends are connected with the positive pole of the first stabilized voltage supply, resistance R 14 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 supply insulation against ground 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 output terminal of described 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. according to a kind of direct supply insulation against ground impedance detection device described in claim 1 or 2 or 3, it is characterized in that: described simulating signal isolation module (4) is linear optical coupling.

5. according to a kind of direct supply insulation against ground impedance detection device described in claim 1 or 2 or 3, it is characterized in that: also comprise switch actuator part (8), described switch actuator part (8) is connected into a loop with direct supply (6) and load, and the control end of described switch actuator part (8) is connected with the output terminal of threshold value comparator circuit (5).

6. according to a kind of direct supply insulation against ground impedance detection device described in 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).

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