CN106154046A - Impedance ground detection device - Google Patents

Abstract

The invention discloses a kind of impedance ground detection device, be coupled to include that the first power line, second source line and the power system of earth lead, this impedance ground detection device include impedance ground testing circuit and controller.Impedance ground testing circuit, including the first input node and the second input node, wherein the first input node is coupled to the first power line and the one of second source line, second input node is coupled to the earth terminal of this impedance ground detection device, wherein impedance ground testing circuit is according to the first input node and the voltage of the second input node and DC reference voltage, and produces VD.Controller is according to DC reference voltage and VD, and judges the impedance ground between earth lead and earth terminal.

Description

Impedance ground detection device

Technical field

The present invention relates to a kind of impedance ground detection device, measure earth lead and earth terminal particularly to one Between the detection device of resistance value.

Background technology

When local side equipment is coupled to power system, local side equipment lacks the situation of good ground connection not Accepted, and the risk of local side equipment fault is risen therewith.Lack effective earthed system will cause Various problems, such as instrument error (instrumentation errors), harmonic distortion, power factor And other many possible intermittent difficult problems will occur therewith.Without by correct design with And the earthed system often safeguarded provides fault current to get rid of to earth's surface, fault current is understood oneself and is found out Beyond thought electric charge gets rid of path, in some instances it may even be possible to cause the crisis that user gets an electric shock.

Additionally, good earthed system also can effectively prevent from damaging factory and equipment, it is therefore necessary to improve The reliability of equipment, and reduce because of fault current damage equipment and the probability causing personnel to get an electric shock.Again Person, if if can learning the resistance value of impedance ground before power system operation, it is right to avoid The too high power system of impedance ground operates, and then is avoided effect that crisis occurs in advance.

Summary of the invention

In view of this, the present invention proposes a kind of impedance ground detection device, is coupled to unified power system, its Described in power system include one first power line, a second source line and an earth lead, impedance ground Detection device includes: an impedance ground testing circuit and a controller.Described impedance ground testing circuit Including one first input node and one second input node, wherein said first input node is coupled to institute Stating the first power line and the one of described second source line, described second input node is coupled to this ground connection One earth terminal of impedance detection device, wherein said impedance ground testing circuit is according to described first input joint Point and the voltage of described second input node and a DC reference voltage (V_REF) and to produce a direct current defeated Go out voltage (V_OUT).Described controller according to described DC reference voltage and described VD, Judge an impedance ground value (R of an impedance ground between described earth lead and described earth terminal_PE)。

According to one embodiment of the invention, described power system is a single-phase three-wire system, described power train System includes that a live wire, a neutral conductor and described earth lead, described first input node are coupled to described fire Line and the described neutral conductor one of them.

According to another embodiment of the present invention, described power system is a biphase three-wire system, described electric power System includes one first live wire, one second live wire and described earth lead, and described first live wire has one One phase place and described second live wire have a second phase, and wherein said first input node is coupled to institute State the arbitrary of the first live wire and described second live wire.

According to still another embodiment of the invention, described power system is a three-phase four wire system, described electric power System includes one first live wire, one second live wire, one the 3rd live wire and described earth lead, described first Live wire has a first phase, described second live wire has a second phase and described 3rd live wire has One third phase, wherein said first input node be coupled to described first live wire, described second live wire with And described 3rd live wire one of them.

According to one embodiment of the invention, described impedance ground testing circuit further includes: one first computing is put Big device, one first resistance, one second resistance, one the 3rd resistance, one the 4th resistance, one first electric capacity with And one second electric capacity.Described first operational amplifier includes one first positive input node and one first negative defeated Ingress, wherein said first operational amplifier receives a direct current supply voltage and comparison is the most described first the most defeated Ingress and the magnitude of voltage of described first negative input node, and it is defeated to produce described direct current in an output node Go out voltage.Described first resistance has one first resistance value (R₁), and it is coupled to described first input joint Between point and described first negative input node.Described second resistance has one second resistance value (R₂), And be coupled between described first negative input node and described output node.Described 3rd resistance has one 3rd resistance value (R₃), and be coupled to described second input node and described first positive input node it Between.Described 4th resistance has one the 4th resistance value (R₄), and be coupled to a reference input node and Between described first positive input node, wherein said DC reference voltage (V_REF) provide to described with reference to defeated Ingress.Described first electric capacity is coupled between described output node and described first negative input node, Described second electric capacity is coupled between described first positive input node and described reference input node, wherein Described first input node includes that an AC signal, described first electric capacity and described second electric capacity are in order to select Select a bandwidth to filter described AC signal.

According to one embodiment of the invention, described impedance ground testing circuit further includes one first clamp circuit. Described first clamp circuit is coupled to described negative input node, in order to provide described negative input node clamp to protect Protect.

According to one embodiment of the invention, described controller according to $R_{\mathrm{PE}}=\frac{R_3\·(R_1+R_2)\·V_{\mathrm{REF}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{REF}}}$ Formula, obtain described ground connection Resistance value；Wherein V_OUTDraw for measuring.

According to one embodiment of the invention, impedance ground detection device further includes an ac voltage detection circuit. Described ac voltage detection circuit includes one the 3rd input node and one the 4th input node, wherein said 3rd input node is coupled to described first power line, and described 4th input node is coupled to described second electricity Source line, wherein said ac voltage detection circuit is according to described 3rd input node and described 4th input One alternating voltage of node and export a detection voltage, wherein said detection voltage includes a direct current component (V_DC) and an AC portion, described controller is sentenced according to the amplitude (AM) of described AC portion Disconnected described alternating voltage (V_M) size, and according to described direct current component and described VD (V_OUT) and judge the size of described impedance ground value.

According to one embodiment of the invention, described ac voltage detection circuit includes: one second operation amplifier Device, one the 5th resistance, one the 6th resistance, one the 7th resistance, one the 8th resistance, one the 3rd electric capacity and One the 4th electric capacity.Described second operational amplifier includes one second positive input node and one second negative input Node, wherein said second operational amplifier receives a direct current supply voltage and compares described second positive input Node and the magnitude of voltage of described second negative input node, and export described detection in a detection voltage node Voltage.Described 5th resistance has one the 5th resistance value (R₅), and it is coupled to described 3rd input node And between described second negative input node.Described 6th resistance has one the 6th resistance value (R₆), and It is coupled between described second negative input node and described detection voltage node.Described 7th resistance has One the 7th resistance value (R₇), and it is coupled to described 4th input node and described second positive input node Between.Described 8th resistance has one the 8th resistance value (R₈), and be coupled to a reference input node with And between described second positive input node, wherein said DC reference voltage provides to described reference input and saves Point.Described 3rd electric capacity, is coupled between described detection voltage node and described second negative input node, Described 4th electric capacity is coupled between described second positive input node and described reference input node, wherein Described 3rd electric capacity and described 4th electric capacity are in order to filter a high-frequency noise.

According to one embodiment of the invention, described ac voltage detection circuit includes: one second clamp circuit And one the 3rd clamp circuit.Described second clamp circuit is coupled to described second negative input node, in order to Described second negative input node clamping protection is provided.Described 3rd clamp circuit is coupled to described second the most defeated Ingress, in order to provide described second positive input node clamping protection.

According to one embodiment of the invention, described controller according to $R_{\mathrm{PE}}=\frac{R_3\·(R_1+R_2)\·V_{\mathrm{DC}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{DC}}}$ Reference formula, obtain described in connect Ground resistance value；Wherein V_OUTDraw for measuring.

Accompanying drawing explanation

Fig. 1 shows the block diagram block detecting device according to the impedance ground described in one embodiment of the invention Figure；

Fig. 2 shows the circuit diagram according to the impedance ground testing circuit described in one embodiment of the invention；

Fig. 3 shows the block diagram side of impedance ground detection device described according to another embodiment of the present invention Block diagram；

Fig. 4 shows the circuit diagram according to the ac voltage detection circuit described in one embodiment of the invention.

Wherein, reference:

100,200,300 impedance ground detection device

101,301 impedance ground testing circuit

102,302 1 controller

110 power systems

201 first operational amplifiers

202 first resistance

203 second resistance

204 the 3rd resistance

205 the 4th resistance

206 first clamp circuits

207 first electric capacity

208 second electric capacity

303,400 ac voltage detection circuit

401 second operational amplifiers

402 the 5th resistance

403 the 6th resistance

404 the 7th resistance

405 the 8th resistance

406 second clamp circuits

407 the 3rd clamp circuits

408 the 3rd electric capacity

409 the 4th electric capacity

P1 the first power line

P2 second source line

PE earth lead

N_I1First input node

N_I2Second input node

N_I33rd input node

N_I44th input node

R_PEImpedance ground

N_REFReference input node

V_REFDC reference voltage

N_OUTOutput node

V_OUTVD

N_P1First positive input node

N_N1First negative input node

N_P2Second positive input node

N_N2Second negative input node

V_SDirect current supply voltage

N_DTDetection voltage node

V_DTDetection voltage

Detailed description of the invention

For making the above-mentioned purpose of the present invention, feature and advantage to become apparent, hereafter the most real especially exemplified by one Execute example, and coordinate institute's accompanying drawings, be described in detail below:

Described below according to preferred embodiment of the present invention.Must be noted that the present invention provides Many applicable inventive concepts, the specific embodiment disclosed at this, it is only for explanation and reaches and fortune By the ad hoc fashion of the present invention, and unavailable to limit to the scope of the present invention.

Fig. 1 shows the block diagram detecting device according to the impedance ground described in one embodiment of the invention.Such as figure Shown in 1, impedance ground detection device 100 includes impedance ground testing circuit 101 and controller 102, Impedance ground detection device 100 be coupled to power system 110, power system 110 have the first power line P1, Second source line P2 and earth lead PE, wherein power system 110 is in order to output AC voltage.According to this One embodiment of invention, impedance ground detection device 100 is the electric power converter connecting power system, such as car Use charging station.

Impedance ground testing circuit 101 includes the first input node N_I1And second input node N_I2, the One input node N_I1It is coupled to the first power line P1 and the one of second source line P2, the second input joint Point N_I2It is coupled to the earth terminal of this impedance ground detection device, wherein between earth lead PE and earth terminal There is impedance ground R_PE, impedance ground testing circuit 101 is according to the first input node N_I1And second is defeated Ingress N_I2Voltage and DC reference voltage V_REF, and in output node N_OUTGeneration direct current exports Voltage V_OUT。

It is to be understood that earth lead PE is grounding wire of power system, and earth terminal is impedance ground detection dress Put the local device earth terminal (local ground) of 100.It is an advantage of the current invention that merely with impedance ground The direct current supply voltage of detection device 100 this locality and the earth terminal of this locality, can estimate the earth terminal of this locality Impedance to long-range earth lead.The evaluation method of the present invention will be in describing the most in detail.

According to one embodiment of the invention, controller 102 is according to DC reference voltage V_REFAnd measure The VD V gone out_OUTMagnitude of voltage, and judge impedance ground R_PEImpedance ground value.Below Will be explained in impedance ground R_PEWith DC reference voltage V_REFAnd measure the VD drawn V_OUTDetailed relation.

According to one embodiment of the invention, power system 110 is single-phase three-wire system, and includes live wire (live Wire), the neutral conductor (neutral wire) and earth lead (earth line), namely the first power line P1 and second source line P2 is respectively live wire (live wire) and the neutral conductor (neutral wire). When the first input node N_I1Be coupled to live wire and the neutral conductor one of them time, impedance ground testing circuit 101 Can be according to the first input node N_I1And second input node N_I2Voltage and DC reference voltage V_REFAnd produce VD V_OUT。

According to another embodiment of the present invention, power system 110 is two-phase, three-wire system, and includes the first fire Line (Line 1), the second live wire (Line 2) and earth lead (earth line), namely the first power supply Line P1 and second source line P2 is respectively the first live wire and the second live wire.When the first input node N_I1 Be coupled to the first live wire and the second live wire one of them time, impedance ground testing circuit 101 can be according to One input node N_I1And second input node N_I2Voltage and DC reference voltage V_REFAnd produce straight Stream output voltage V_OUT。

According to still another embodiment of the invention, power system 110 is three-phase four wire system, and includes the first fire Line (R), the second live wire (S), the 3rd live wire (T) and earth lead, wherein the first live wire, second Phase contrast between live wire and the 3rd live wire is all 120 degree.Now, power system 110 has the first electricity Source line P1, second source line P2 and the 3rd power line P3, wherein power system 110 has the first electricity Source line P1, second source line P2 and the 3rd power line P3 be respectively the first live wire, the second live wire and 3rd live wire.When the first input node N_I1It is coupled to the first live wire, the second live wire and the 3rd live wire wherein For the moment, impedance ground testing circuit 101 can be according to the first input node N_I1And second input node N_I2Voltage and DC reference voltage V_REFAnd produce VD V_OUT。

Fig. 2 shows the circuit diagram according to the impedance ground testing circuit described in one embodiment of the invention.Such as figure Shown in 2, impedance ground testing circuit 200 include first operational amplifier the 201, first resistance 202, Two resistance the 203, the 3rd resistance the 204, the 4th resistance the 205, first clamp circuit the 206, first electric capacity 207 And second electric capacity 208.

First operational amplifier 201 includes the first positive input node N_P1And the first negative input node N_N1, Wherein the first operational amplifier 201 receives direct current supply voltage V_S, and compare the first positive input node N_P1 And the first negative input node N_N1Voltage, and in output node N_OUTProduce VD V_OUT。

First resistance 202 has the first resistance value R1, and is coupled to the first input node N_I1And first Negative input node N_N1Between.According to one embodiment of the invention, the first resistance 202 is with several resistance strings Connect, to meet the insulation distance of safety.Second resistance 203 has the second resistance value R₂, and be coupled to First negative input node N_N1And output node N_OUTBetween.

3rd resistance 204 has the 3rd resistance value R₃, and it is coupled to the second input node N_I2And first Positive input node N_P1Between, wherein the second input node N_I2It is coupled to connecing of this impedance ground detection device Ground end.4th resistance 205 has the 4th resistance value R₄, and it is coupled to reference input node N_REFAnd First positive input node N_P1Between, wherein DC reference voltage V_REFThere is provided to reference input node N_REF。

First clamp circuit 206 is coupled to the first negative input node N_N1, in order to eliminate the first negative input node N_N1Surging, that is provide clamping protection.First electric capacity 207 is coupled to output node N_OUTAnd the One negative input node N_N1Between, one second electric capacity 208 is coupled to the first positive input node N_P1And reference Input node N_REFBetween, wherein the first electric capacity 207 and the second electric capacity 208 are in order to examine impedance ground Slowdown monitoring circuit 200 is designed as low-pass amplifier, and the first electric capacity 207 and the second electric capacity 208 are in order to select a band Width, and then filter from the first input node N_I1And second input node N_I2AC signal, to subtract The impact on impedance ground testing circuit 200 of the little AC signal, utilizes the low-pass characteristic can be in output node N_OUT Produce VD V_OUT。

When DC reference voltage V_REFWhen injecting impedance ground testing circuit 200, impedance ground testing circuit 200 according to the first input node N_I1And second input node N_I2Voltage and DC reference voltage V_REF And produce VD V_OUT, controller 102 is more according to measuring the VD V drawn_OUT And DC reference voltage V_REFDifference calculate impedance ground R_PE。

According to one embodiment of the invention, direct current supply voltage V_SFor 12V, DC reference voltage V_REFFor 6V, and impedance ground R_PEEquivalence is coupled to the first input node N_I1And between earth terminal, the first electricity Resistance R₁And the 3rd resistance value R₃For 1000k Ω, the second resistance value R2 and the 4th resistance value R₄For 402kΩ.But, the first resistance value R₁, the second resistance value R₂, the 3rd resistance value R₃And the 4th resistance Value R₄Can arbitrarily select, at this for convenience of explanation, select the first resistance value R₁Equal to the 3rd resistance value R₃And second resistance value R₂Equal to the 4th resistance value R₄。

Due to the first input node N_I1It is coupled to the first power line P1 and of Fig. 1 power system 110 Two power line P2 one of them, and power system 110 utilizes the first power line P1 and second source line P2 output AC voltage, because by the electricity that impedance ground testing circuit 200 is designed as a low-pass characteristic Road, so output voltage V_OUTFor flip-flop, therefore analysis below all has only to consider flip-flop.The One positive input node N_P1Magnitude of voltage V_P1Can be obtained by formula 1:

$V_{P1}=\frac{R_3}{R_3+R_4}\·V_{\mathrm{REF}}$ (formula 1)

Due to the 3rd resistance value R₃For 1000k Ω, the 4th resistance value R₄For 402k Ω and DC reference electricity Pressure V_REFFor 6V, therefore the first positive input node N_P1Magnitude of voltage V_P1For 4.28V.Due to preferably The enlargement ratio of operational amplifier is infinitely great, if therefore the first operational amplifier 201 is considered as preferable amplification If device, the first positive input node N_P1And the first negative input node N_N1Can be considered imaginary short (virtual short circuit)。

It is, the first negative input node N_N1Magnitude of voltage V_N1Equal to the first positive input node N_P1Electricity Pressure value V_P1And it is 4.28V, VD V_OUTCan obtain via formula 2:

$V_{\mathrm{OUT}}=\frac{R_1+R_2+R_{\mathrm{PE}}}{R_1+R_{\mathrm{PE}}}\·V_{P1}$ (formula 2)

The controller 102 of Fig. 1 is via comparing DC reference voltage V_REFAnd measure the direct current output drawn Voltage V_OUTDifference, impedance ground R can be learnt_PEResistance value.

Formula (2) according to the present invention can draw formula (3), the available public affairs of controller 102 in conjunction with formula (1) Formula 3 calculates impedance ground R_PEResistance value.

$R_{\mathrm{PE}}=\frac{R_3\·(R_1+R_2)\·V_{\mathrm{REF}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{REF}}}$ (formula 3)

In other words, the controller 102 of Fig. 1 can be according to the first resistance value R₁, the second resistance value R₂, straight Stream reference voltage V_REFAnd measure the VD V drawn_OUT, utilize formula 3 to calculate ground connection Impedance R_PEResistance value.

According to another embodiment of the present invention, due to the stray capacitance on signal path and in order to filtering interfering Electric capacity detection all can be made to produce error, the calculation of the most described impedance ground needs corresponding repairing Just.

Fig. 3 shows the block diagram of impedance ground detection device described according to another embodiment of the present invention.As Shown in Fig. 3, impedance ground detection device 300 include impedance ground testing circuit 301, controller 302 with And ac voltage detection circuit 303.Compared to Figure 1, impedance ground detection device 300 relatively impedance ground inspection Survey device more than 100 ac voltage detection circuit 303.

Ac voltage detection circuit 303 includes the 3rd input node N_I3And the 4th input node N_I4, its 3rd input node N of middle ac voltage detection circuit 303_I3And the 4th input node N_I4It is respectively coupled to To the first power line P1 and second source line P2, in order to detect the first power line P1 and second source The alternating voltage V of line P2_M, and in detection voltage node N_DTOutput detections voltage V_DT。

It is to be understood that earth lead PE and earth terminal are belonging respectively to power system 310 and impedance ground inspection Survey the ground connection of device 300.

Detection voltage V_DTIncluding direct current component V_DCAnd AC portion V_AC, controller 302 is according to direct current Part V_DCAnd measure the VD V drawn_OUTAnd utilize formula 4 to calculate impedance ground R_PE Resistance value.In other words, formula 4 is with direct current component V_DCReplace DC reference voltage V_REFTry to achieve and connect Ground impedance R_PE.Controller 302 more utilizes AC portion V_ACAmplitude A M obtain power system 310 warp The size of the alternating voltage VM provided by the first power line P1 and second source line P2.

$R_{\mathrm{PE}}=\frac{R_3\·(R_1+R_2)\·V_{\mathrm{DC}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{DC}}}$ (formula 4)

According to one embodiment of the invention, owing to controller 302 needs by ac voltage detection circuit 303 Detect the alternating voltage V that power system 310 is exported_MIf controller 302 is still with DC reference voltage V_REFAnd measure the VD V drawn_OUTTry to achieve impedance ground R_PEIf, it is necessary to additionally profit With a stitch by DC reference voltage V_REFThere is provided to controller 302.It is, controller 302 utilizes inspection Survey voltage V_DTDirect current component V_DCAnd measure the VD V drawn_OUTTry to achieve impedance ground R_PETime, then it is not required to DC reference voltage V additionally_REFThere is provided to controller 302, the pin of controller 302 Foot also can be saved as other purposes.

Fig. 4 shows the circuit diagram according to the ac voltage detection circuit described in one embodiment of the invention.Such as figure Shown in 4, ac voltage detection circuit 400 include the second operational amplifier 401, the 5th resistance 402, Six resistance the 403, the 7th resistance the 404, the 8th resistance the 405, second clamp circuit the 406, the 3rd clamp circuits 407, the 3rd electric capacity 408 and the 4th electric capacity 409.

Second operational amplifier 401 includes the second positive input node N_P2And one second negative input node N_N2, Wherein the second operational amplifier 401 receives direct current supply voltage V_SAnd compare the second positive input node N_P2With And the second negative input node N_N2Magnitude of voltage, and in detection voltage node N_DTProduce detection voltage V_DT。

5th resistance 402 has the 5th resistance value R₅, and it is coupled to the 3rd input node N_I3And second Negative input node N_N2Between.According to one embodiment of the invention, the 5th resistance 402 is with several resistance strings Connect, to meet the insulation distance of safety.6th resistance 403 has the 6th resistance value R₆, and be coupled to Second negative input node N_N2And detection voltage node N_DTBetween.

7th resistance 404 has the 7th resistance value R₇, and it is coupled to the 4th input node N_I4And second Positive input node N_P2Between.According to one embodiment of the invention, the 7th resistance 404 is with several resistance strings Connect, to meet the insulation distance of safety.8th resistance 405 has the 8th resistance value R₈, and be coupled to Reference input node N_REFAnd the second positive input node N_P2Between, wherein DC reference voltage V_REFCarry It is supplied to described reference input node N_REF。

Second clamp circuit 406 is coupled to the second negative input node N_N2, in order to eliminate the second negative input node N_N2Surging.3rd clamp circuit is coupled to the second positive input node N_P2, in order to eliminate the second positive input Node N_P2Surging.

3rd electric capacity 408 is coupled to detect voltage node N_DTAnd the second negative input node N_N2Between.The Four electric capacity 409 are coupled to the second positive input node N_P2And reference input node N_REFBetween, Qi Zhong Three electric capacity 408 and the 4th electric capacity 409 can be by making detection voltage in order to select a band to be tolerant alternating component V_DTIncluding direct current component V_DCAnd AC portion V_AC, and high-frequency noise can be filtered.

According to one embodiment of the invention, direct current supply voltage Vs is 12V, DC reference voltage V_REF For 6V, and the exchange that power system 310 exports via the first power line P1 and second source line P2 Voltage V_MRoot-mean-square (root mean square, RMS) size be 220V, the 5th resistance value R₅And 7th resistance value R₇For 1000k Ω, the 6th resistance value R₆And the 8th resistance value R₈For 12.1k Ω.

When the 3rd input node N_I3And the 4th input node N_I4Be respectively coupled to the first power line P1 and During second source line P2, the 3rd input node N_N3And the 4th input node N_I4Between alternating voltage V_MFor 220V.Therefore, as alternating voltage V_MRoot-mean-square when being 220V, its peak value is 311.08V, Detection voltage V_DTAC portion V_ACAmplitude A M be 3.764V.

In other words, controller 302 can be according to detection voltage V_DTAC portion V_ACAmplitude A M, 5th resistance value R₅, the 6th resistance value R₆, the 7th resistance value R₇And the 8th resistance value R₈, push back and Obtain actual alternating voltage V_M。

Therefore, those of ordinary skill in the art can utilize the impedance ground testing circuit 200 of Fig. 2 of the present invention The VD V exported_OUT, in conjunction with impedance ground testing circuit 200 the first resistance 202, Two resistance the 203, the 3rd resistance the 204, the 4th resistance 205 and DC reference voltage V_REFDesign parameter, And calculate impedance ground value R accurately with formula 3_PE。

When needing the input stitch reducing controller, then may utilize the alternating voltage detection of Fig. 4 of the present invention 400 output detections voltage V of circuit_DTDirect current component V_DCReplace DC reference voltage V_REF, then with Formula 4 calculates impedance ground value R accurately_PE.Wherein, controller can be by output detections voltage V_DTFlat All obtain replacing DC reference voltage V_REF, and voltage V can be detected simultaneously_DTAC portion V_AC, can save Go DC reference voltage V_REFInput the input stitch to controller.

The feature of many embodiments described above, enables have usually intellectual in art clear Understand the form of this specification.Art has usually intellectual it will be appreciated that it may utilize this Complete to be same as above-described embodiment to design or change other processing procedures and structure based on bright disclosure Purpose and/or reach to be same as the advantage of above-described embodiment.Art also has usually intellectual It will be appreciated that without departing from the spirit and scope of the present invention equivalent constructions can without departing from the present invention spirit and In the range of change arbitrarily, substitute and retouch, but these change accordingly, substitute and retouch and all should belong to The protection domain of appended claims of the invention.

Claims (11)

1. an impedance ground detection device, is coupled to unified power system, and described power system includes one the One power line, a second source line and an earth lead, wherein, this impedance ground detection device includes:

One impedance ground testing circuit, including one first input node and one second input node, Qi Zhongsuo State the first input node be coupled to described first power line and described second source line one of them, described Two input nodes are coupled to an earth terminal of this impedance ground detection device, wherein said impedance ground detection electricity Road is according to described first input node and the voltage of described second input node and a DC reference voltage (V_REF), and produce a VD (V_OUT)；And

One controller, according to described DC reference voltage and described VD, it is judged that described ground connection One impedance ground value (R of the impedance ground between line and described earth terminal_PE)。

2. impedance ground detection device as claimed in claim 1, wherein, described power system is a list Phase three-wire system, described power system includes a live wire, a neutral conductor and described earth lead, described first Input node be coupled to described live wire and the described neutral conductor one of them.

3. impedance ground detection device as claimed in claim 1, wherein, described power system is one or two Phase three-wire system, described power system includes one first live wire, one second live wire and described earth lead, institute State the first live wire and there is a first phase and described second live wire has a second phase, wherein said first Input node be coupled to described first live wire and described second live wire one of them.

4. impedance ground detection device as claimed in claim 1, wherein, described power system is one or three Phase four-wire system, described power system includes one first live wire, one second live wire, one the 3rd live wire and institute State earth lead, described first live wire has a first phase, described second live wire has a second phase and Described 3rd live wire has a third phase, wherein said first input node be coupled to described first live wire, Described second live wire and described 3rd live wire one of them.

5. impedance ground detection device as claimed in claim 1, wherein, described impedance ground detection electricity Road also includes:

One first operational amplifier, including one first positive input node and one first negative input node, wherein Described first operational amplifier receives a direct current supply voltage and compares described first positive input node and institute State the magnitude of voltage of the first negative input node, and produce described VD in an output node；

One first resistance, has one first resistance value (R₁) and be coupled to described first input node and institute State between the first negative input node；

One second resistance, has one second resistance value (R₂) and be coupled to described first negative input node and Between described output node；

One the 3rd resistance, has one the 3rd resistance value (R₃) and be coupled to described second input node and institute State between the first positive input node；

One the 4th resistance, has one the 4th resistance value (R₄) and be coupled to a reference input node and described Between first positive input node, wherein said DC reference voltage (V_REF) provide to described reference input joint Point；

One first electric capacity, is coupled between described output node and described first negative input node；And

One second electric capacity, is coupled between described first positive input node and described reference input node；

Wherein said first input node includes an AC signal, described first electric capacity and described second electric capacity In order to select a bandwidth to filter described AC signal.

6. impedance ground detection device as claimed in claim 5, wherein, described impedance ground detection electricity Road also includes:

One first clamp circuit, is coupled to described negative input node, in order to provide described negative input node to clamp Protection.

7. impedance ground detection device as claimed in claim 5, wherein, described controller according to

$P_{\mathrm{PE}}=\frac{R_3\·(R_1+R_2)\·V_{\mathrm{REF}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{REF}}}$

Formula, obtain described impedance ground value；Wherein V_OUTDraw for measuring.

8. the impedance ground detection device as described in claim 1 or 5, wherein, also includes:

One ac voltage detection circuit, including one the 3rd input node and one the 4th input node, Qi Zhongsuo Stating the 3rd input node and be coupled to described first power line, described 4th input node is coupled to described second electricity Source line, wherein said ac voltage detection circuit is according to described 3rd input node and described 4th input joint Point an alternating voltage and export a detection voltage, wherein said detection voltage includes a direct current component (V_DC) And an AC portion, described controller judges described friendship according to the amplitude (AM) of described AC portion Stream voltage (V_M) size, and judge institute according to described direct current component and described VD State the size of impedance ground value.

9. impedance ground detection device as claimed in claim 8, wherein, described alternating voltage detection electricity Road includes:

One second operational amplifier, including one second positive input node and one second negative input node, wherein Described second operational amplifier receives a direct current supply voltage and compares described second positive input node and institute State the magnitude of voltage of the second negative input node, and export described detection voltage in a detection voltage node；

One the 5th resistance, has one the 5th resistance value (R₅) and be coupled to described 3rd input node and institute State between the second negative input node；

One the 6th resistance, has one the 6th resistance value (R₆) and be coupled to described second negative input node and Between described detection voltage node；

One the 7th resistance, has one the 7th resistance value (R₇) and be coupled to described 4th input node and institute State between the second positive input node；

One the 8th resistance, has one the 8th resistance value (R₈) and be coupled to a reference input node and described Between second positive input node, wherein said DC reference voltage provides to described reference input node；

One the 3rd electric capacity, is coupled between described detection voltage node and described second negative input node；With And

One the 4th electric capacity, is coupled between described second positive input node and described reference input node；

Wherein said 3rd electric capacity and described 4th electric capacity are in order to filter a high-frequency noise.

10. impedance ground detection device as claimed in claim 9, wherein, described alternating voltage detection electricity Road includes:

One second clamp circuit, is coupled to described second negative input node, in order to provide described second negative input Node clamping protection；And

One the 3rd clamp circuit, is coupled to described second positive input node, in order to provide described second positive input Node clamping protection.

Impedance ground that 11. such as claim 9 state detection device, wherein, described controller according to

$R_{\mathrm{PE}}=\frac{R_3\⊂⃒(R_1+R_2)\·V_{\mathrm{DC}}-R_1\·(R_3+R_4)\·V_{\mathrm{OUT}}}{(R_3+R_4)\·V_{\mathrm{OUT}}-R_3\·V_{\mathrm{DC}}}$

Formula, obtain described impedance ground value；Wherein V_OUTDraw for measuring.