CN202648823U - Single constant current source and multichannel thermal resistance measuring system - Google Patents
Single constant current source and multichannel thermal resistance measuring system Download PDFInfo
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- CN202648823U CN202648823U CN 201220215855 CN201220215855U CN202648823U CN 202648823 U CN202648823 U CN 202648823U CN 201220215855 CN201220215855 CN 201220215855 CN 201220215855 U CN201220215855 U CN 201220215855U CN 202648823 U CN202648823 U CN 202648823U
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Abstract
A single constant current source and multichannel thermal resistance measuring system comprises a constant current source circuit, a reference resistance sampling circuit, and a thermal resistance measuring circuit; an output terminal of the dual shift single constant current source circuit is respectively connected with an current input terminal of the reference resistance sampling circuit and an input terminal of the thermal resistance measuring circuit; an references voltage input terminal of the thermal resistance measuring circuit is connected with an voltage output terminal of the reference resistance sampling circuit; an output terminal of the thermal resistance measuring circuit is an measuring terminal of an resistor RTDx to be measured; the thermal resistance measuring circuit comprises a plurality of same circuits, and the circuits are in parallel connection; the constant current source circuit comprises a dual shift references voltage source circuit and the constant current source circuit; and compared with prior art, a technical scheme of the utility model solves device symmetrical problems encountered in building a dual constant current source circuit in a three-wire thermal resistance measuring system, a problem of a small scope of the thermal resistance measurement is solved, and simultaneously troubles caused by zero setting resistance is solved.
Description
Technical field
The utility model relates to a kind of thermal resistance measuring system, especially a kind of single constant current source Multi-channel hot resistance measuring system of Wide measuring range.
Background technology
In commercial production, thermal resistance often is applied to the occasion higher to the temperature measurement accuracy requirement as temperature-sensing element.Thermal resistance type commonly used has Cu50, Cu53, Pt10, Pt100 and Pt1000, and when wherein temperature measurement accuracy required to be 0.1 ℃, it is more extensive that Cu50 and Pt100 use, and when accuracy requirement was 0.01 ℃, the application of Pt1000 was just many.Thermal resistance generally is applied to the temperature survey that the temperature survey of middle low-temperature space: Cu50 generally is applied to-50 ℃～150 ℃ in commercial production, and the Standard resistance range of corresponding thermal resistance is 78.48 ohm～164.27 ohm; The Pt100 temperature-measuring range is-200 ℃～850 ℃, and corresponding Standard resistance range is 18.52 ohm～390.84 ohm; The temperature-measuring range that Pt1000 is commonly used is-50 ℃～300 ℃, and corresponding Standard resistance range is 803.063 ohm～2120.515 ohm.Existing temperature measuring equipment temperature measurement range is narrow, as for Pt100, is mostly to be applied to-50 ℃～300 ℃, and the measuring accuracy that surpasses 300 ℃ will reduce greatly, more not only can measure Pt100 but also can measure Pt1000 without a bill of lading equipment.
At present, thermal resistance measurement method commonly used has several, and two wires, three lines and four-wire method are arranged with regard to hot wire system, mainly contains bridge method and Method of constant flow source with regard to energisation mode.
The sensitivity of thermal resistance is higher, is approximately 0.38 ohm/℃ such as the sensitivity of commonly using the Pt100 thermal resistance, so the resistance of wire can not be ignored in the measurement of thermal resistance.Two-wire system can't be eliminated line resistance to the impact of measurement result, and the occasion high in accuracy requirement generally can not adopt; Four-wire method can be eliminated the impact of line resistance, but many wiring costs are too high for the multichannel temp measuring system of long distance; Three-wire system can be eliminated by the processing on hardware or the software impact of line resistance, and is lower than the realization cost of four-wire system, is the selection commonly used in the hyperchannel temp measuring system.
In the three-wire system thermal resistance was measured, although that bridge method can be eliminated the impact measurement range of line resistance is narrower, so the constant current source method was temp measuring method commonly used at present.In the Multi-channel hot resistance measuring system, often use the measuring method of many constant current sources (passage uses a constant current source) or two constant current sources.Wherein, the realization cost of many Method of constant flow sources is high, and the discreteness between different constant current source can be brought extra error to measurement result; Two Method of constant flow sources are had relatively high expectations to the symmetry of constant current source, and commutation circuit is comparatively loaded down with trivial details, can take larger board area.
Summary of the invention
The present invention is directed to above problem, single constant current source application scheme in a kind of Multi-channel hot resistance measuring system has been proposed, measure in the application at hyperchannel three-wire system thermal resistance, utilize a kind of folk art term constant current source to expand temperature measurement range, utilize single constant current source to reduce scheme and realize cost, use one group of change-over switch to realize the switchings of measuring passages, and the measurement of quoting reference channel on the basis that passage switches has solved the demanding difficult problem of two constant current source symmetry and has avoided the trouble that zero-regulator resistor brings in the ordinary hot resistance measuring system production run more.
The technical scheme that the utility model adopts is:
A kind of single constant current source Multi-channel hot resistance measuring system comprises constant-current source circuit, reference resistance sample circuit and thermal resistance metering circuit; The output terminal of described constant-current source circuit connects respectively the current input terminal of reference resistance sample circuit and the input end of thermal resistance metering circuit; The reference voltage voltage input end of thermal resistance metering circuit connects the voltage output end of described reference resistance sample circuit; The output terminal of described thermal resistance metering circuit is measured resistance R
TDxMeasuring junction;
It is identical and parallel with one another a plurality of to it is characterized in that described thermal resistance metering circuit comprises; Described constant-current source circuit comprises the folk art term reference voltage source circuit;
Described folk art term reference voltage source circuit comprises resistance R 1, R2, R3 and R4, stabilivolt Z1 and two-way switch U1A, U1B; After resistance R 2, R3 and R4 were cascaded first successively, in parallel with stabilivolt Z1 again, the cathode terminal of stabilivolt Z1 connected R2, and the anode tap of Z1 connects R4; One end of described resistance R 1 connects power supply AVCC end, and the other end connects the cathode terminal of stabilivolt Z1; Between the end contact resistance R2 and R3 of described two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1A is S1; Between the other end contact resistance R4 and R3 of two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1B is S2; S1 end and S2 end are not gating simultaneously; The cathode terminal of described stabilivolt Z1 connects its working power AVCC1 end, the anode tap ground connection of Z1;
Described constant-current source circuit comprises resistance R 5, R6 and R7, amplifier OP1 and triode Q1; One end of resistance R 7 connects power supply AVCC end, the emitter of other end connecting triode Q1; One end of resistance R 5 connects the emitter of Q1, and the other end connects the negative input end of amplifier OP1, and the positive input terminal of OP1 connects described output signal AVCC2 end; The output terminal of amplifier OP1 is by the collector of resistance R 6 connecting triode Q1; The collector of triode Q1 is as the current output terminal of this constant-current source circuit.
In the described thermal resistance metering circuit any is single channel thermal resistance commutation circuit; For any single channel thermal resistance commutation circuit, comprise resistance R Ax, RBx, RCx, RDx, REx, RFx and RGx, two-way change-over switch UAx and UBx, and single channel change-over switch UCx; The corresponding channel B of measuring of described UAx, the corresponding channel C of measuring of UBx, the corresponding passage A that measures of UCx;
Described single channel change-over switch UCx is light coupling relay, and its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of light coupling relay, and the 4th, 6 pins are corresponding output terminal;
Described two-way change-over switch UAx is identical with UBx, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
The 2nd pin of described UCx connects respectively the 4th pin of described UAx and UBx, and interface channel is selected signal CSx end;
The 1st pin of described UCx connects power supply VCC end by resistance R Fx; The 1st pin of described UAx connects the VCC end by resistance R Gx;
The 1st pin of described UBx selects pin to connect corresponding selection signal as measuring channel B, and the 3rd pin of UBx selects pin to connect corresponding selection signal as measuring channel C;
The 6th pin of described UAx connects the sampled voltage of reference resistance, and the 4th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, consist of to measure passage A;
The 7th pin of described UAx connects the current output terminal of constant current source, and the 8th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, namely be connected to and measure passage A;
The 5th pin ground connection of described UAx, the 6th pin connects tested thermal resistance R by resistance R Cx
TDxThe other end, consist of to measure channel B;
The 7th pin of described UBx connects the sampled voltage of reference resistance, and the 8th pin connects tested thermal resistance R by resistance R Dx
TDxThe other end, namely be connected to the measurement channel B;
The 6th pin of described UBx connects the sampled voltage of reference resistance, and the 5th pin connects tested thermal resistance R by resistance R Ex
TDxThe other end, consist of to measure channel C.
Described reference resistance sample circuit is the reference resistance commutation circuit, and it comprises resistance R 8, R9, R10 and R0, two two-way change-over switch US1 and US2;
Described resistance R 0 is reference resistance; Two-way change-over switch US1 is identical with US2, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
One end of described resistance R 0 connects the 5th pin of two-way change-over switch US1 and the 7th pin of US2, and the other end connects the 7th pin of US1 and the 5th pin of US2;
The 6th pin of described US1 is the Constant current input end; The 8th pin of one termination US1 of resistance R 10, other end connecting analog ground AGND;
The 8th pin of described US2 and the 6th pin of US2 are as voltage sample pin on the R0 resistance, for follow-up analog quantity sample circuit;
One end of described resistance R 8 connects power supply VCC end, and the other end connects the 1st pin of US1; The 2nd pin of US1 and the 3rd pin of US1 are shorted together, and the 4th pin of US1 is for selecting signal S5 input end; Resistance R 9 one ends connect power supply VCC end, and the other end connects the 1st pin of US2, and the 2nd pin of US2 and the 3rd pin of US2 are shorted together, and the 4th pin of US2 is for selecting signal S5 input end.
Compared with prior art the technical solution of the utility model has avoided building the device symmetry problem that twin-constant-current runs into when three-wire system thermal resistance measuring system, solve the little problem of thermal resistance measurement range, also solved the trouble that zero-regulator resistor brings simultaneously.Generally speaking, this programme has been expanded the measurement range of Multi-channel hot resistance, improve simultaneously stability and the reliability of Multi-channel hot resistance measurement, can be applied to the temperature survey of the multiple industries such as electric power, chemical industry, metallurgy, printing and dyeing, pharmacy and heat supply, had very strong practicality.
Description of drawings
Fig. 1 folk art term reference voltage source circuit of the present utility model figure;
Fig. 2 constant-current source circuit figure of the present utility model;
Fig. 3 folk art term constant-current source circuit of the present utility model figure;
Fig. 4 Multi-channel hot resistance of the present utility model resistance commutation circuit figure;
Fig. 5 benchmark commutation circuit of the present utility model figure.
Embodiment
A kind of single constant current source Multi-channel hot resistance measuring system comprises constant-current source circuit, reference resistance sample circuit and thermal resistance metering circuit; The output terminal of described constant-current source circuit connects respectively the current input terminal of reference resistance sample circuit and the input end of thermal resistance metering circuit; The reference voltage voltage input end of thermal resistance metering circuit connects the voltage output end of described reference resistance sample circuit; The output terminal of described thermal resistance metering circuit is measured resistance R
TDxMeasuring junction;
It is identical and parallel with one another a plurality of to it is characterized in that described thermal resistance metering circuit comprises; Described constant-current source circuit comprises the folk art term reference voltage source circuit;
Described folk art term reference voltage source circuit comprises resistance R 1, R2, R3 and R4, stabilivolt Z1 and two-way switch U1A, U1B; After resistance R 2, R3 and R4 were cascaded first successively, in parallel with stabilivolt Z1 again, the cathode terminal of stabilivolt Z1 connected R2, and the anode tap of Z1 connects R4; One end of described resistance R 1 connects power supply AVCC end, and the other end connects the cathode terminal of stabilivolt Z1; Between the end contact resistance R2 and R3 of described two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1A is S1; Between the other end contact resistance R4 and R3 of two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1B is S2; S1 end and S2 end are not gating simultaneously; The cathode terminal of described stabilivolt Z1 connects its working power AVCC1 end, the anode tap ground connection of Z1;
Described constant-current source circuit comprises resistance R 5, R6 and R7, amplifier OP1 and triode Q1; One end of resistance R 7 connects power supply AVCC end, the emitter of other end connecting triode Q1; One end of resistance R 5 connects the emitter of Q1, and the other end connects the negative input end of amplifier OP1, and the positive input terminal of OP1 connects described output signal AVCC2 end; The output terminal of amplifier OP1 is by the collector of resistance R 6 connecting triode Q1; The collector of triode Q1 is as the current output terminal of this constant-current source circuit.
In the described thermal resistance metering circuit any is single channel thermal resistance commutation circuit; For any single channel thermal resistance commutation circuit, comprise resistance R Ax, RBx, RCx, RDx, REx, RFx and RGx, two-way change-over switch UAx and UBx, and single channel change-over switch UCx; The corresponding channel B of measuring of described UAx, the corresponding channel C of measuring of UBx, the corresponding passage A that measures of UCx;
Described single channel change-over switch UCx is light coupling relay, and its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of light coupling relay, and the 4th, 6 pins are corresponding output terminal;
Described two-way change-over switch UAx is identical with UBx, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
The 2nd pin of described UCx connects respectively the 4th pin of described UAx and UBx, and interface channel is selected signal CSx end;
The 1st pin of described UCx connects power supply VCC end by resistance R Fx; The 1st pin of described UAx connects the VCC end by resistance R Gx;
The 1st pin of described UBx selects pin to connect corresponding selection signal as measuring channel B, and the 3rd pin of UBx selects pin to connect corresponding selection signal as measuring channel C;
The 6th pin of described UAx connects the sampled voltage of reference resistance, and the 4th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, consist of to measure passage A;
The 7th pin of described UAx connects the current output terminal of constant current source, and the 8th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, namely be connected to and measure passage A;
The 5th pin ground connection of described UAx, the 6th pin connects tested thermal resistance R by resistance R Cx
TDxThe other end, consist of to measure channel B;
The 7th pin of described UBx connects the sampled voltage of reference resistance, and the 8th pin connects tested thermal resistance R by resistance R Dx
TDxThe other end, namely be connected to the measurement channel B;
The 6th pin of described UBx connects the sampled voltage of reference resistance, and the 5th pin connects tested thermal resistance R by resistance R Ex
TDxThe other end, consist of to measure channel C.
Described reference resistance sample circuit is the reference resistance commutation circuit, and it comprises resistance R 8, R9, R10 and R0, two two-way change-over switch US1 and US2;
Described resistance R 0 is reference resistance; Two-way change-over switch US1 is identical with US2, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
One end of described resistance R 0 connects the 5th pin of two-way change-over switch US1 and the 7th pin of US2, and the other end connects the 7th pin of US1 and the 5th pin of US2;
The 6th pin of described US1 is the Constant current input end; The 8th pin of one termination US1 of resistance R 10, other end connecting analog ground AGND;
The 8th pin of described US2 and the 6th pin of US2 are as voltage sample pin on the R0 resistance, for follow-up analog quantity sample circuit;
One end of described resistance R 8 connects power supply VCC end, and the other end connects the 1st pin of US1; The 2nd pin of US1 and the 3rd pin of US1 are shorted together, and the 4th pin of US1 is for selecting signal S5 input end; Resistance R 9 one ends connect power supply VCC end, and the other end connects the 1st pin of US2, and the 2nd pin of US2 and the 3rd pin of US2 are shorted together, and the 4th pin of US2 is for selecting signal S5 input end.
The technical program is further specified as follows below in conjunction with accompanying drawing and embodiment:
The folk art term reference voltage source circuit as shown in Figure 1.Wherein, three resistance string of R2-R4 be linked togather with stabilivolt Z1 parallel connection after connect with R1 again, form the secondary bleeder circuit: first order bleeder circuit is comprised of R1 series connection Z1, with the operating voltage AVCC1 of the voltage stabilization between power supply AVCC and the AGND to stabilivolt Z1; Realize the dividing potential drop to AVCC1 after second level bleeder circuit is connected by R2, R3 and R4 and at the Z1 two ends.Two two-way switch U1A and U1B choose respectively the voltage (S1 and S2 be gating simultaneously) at resistance R 3 two ends by signal S1 and S2, output signal is AVCC2, thereby forms the folk art term reference voltage source circuit.R1 can choose resistance and power according to the pressure reduction between AVCC and AVCC1, can choose precision and the less demanding conventional, electric-resistance of temperature coefficient; And R2, R3 need the relative higher Low Drift Temperature resistance of precision with R4, and the resistance ratio of these three resistance is chosen according to two grades of designed constant current source size of current.
The constant-current source circuit principle as shown in Figure 2.Wherein, amplifier OP1 introduces negative feedback the emitter voltage of Q1 is stabilized in about AVCC2, this moment constant current source I=(AVCC-AVCC2)/R7, the size of R7 will be chosen according to AVCC2 and designed constant current source size, R7 preferably selects Low Drift Temperature resistance.The folk art term constant-current source circuit that this constant-current source circuit and folk art term reference voltage source circuit constitute jointly as shown in Figure 3.Wherein, close S1 gating S2 and can form a constant current source that current value is larger, be used for the less thermal resistance of the Standard resistance ranges such as Cu50, Cu53 and Pt100 and measure; Closing S2 gating S1 can form the less constant current source of current value and be used for measuring as the larger thermal resistance of this Standard resistance range of Pt1000 and measure.The precision of this kind constant current source is high, loading range is wide, can guarantee effective precision and the linearity fully in the industrial applicability of Pt100 and Pt1000.
This routine Multi-channel hot resistance commutation circuit as shown in Figure 4, switching front road by a plurality of single channel thermal resistances forms, the thermal resistance commutation circuit principle of single passage as shown in Figure 4, only need to change channel selecting signal CSx(x when increasing the thermal resistance channel circuit is the respective channel numbering) get final product.Embodiment now is described as an example of the first passage circuit example:
When gating channel selecting signal CS1 only, the electric current I of constant current source flows into thermal resistance R through UA1-7, UA1-8 through RA1
TD1The A line, electric current goes out from the B linear flow, returns analog electrical seedbed AGND through resistance R C1 and RA1-6 and UA1-5.
When disconnecting S4 as gating S3, the voltage U 3=U that T1 and T2 two ends record
AD+ U
RTD1+ U
EB=I * (r+R
TD1+ r)=I * (R
TD1+ 2r);
When disconnecting S3 as gating S4, the voltage U 4=U that T1 and T2 two ends record
AD+ U
RTD1=2 * U4-U3=2 * I * (r+R
TD1)-I * (R
TD1+ 2r)=I * R
TD1=U
RTD1
Can get thus, the switching of process S3 and S4 can record the electric current I of constant current source at this passage thermal resistance R by analog to digital conversion
TD1On pressure drop U
RTD1In whole measuring process, only need to when measuring this passage, just other internal circuit in constant-current source circuit and the measuring system and external thermal resistance be connected, and the time that single simulation measurement amount needs is shorter, probably at several milliseconds the order of magnitude, so just greatly reduce external interference and passed to chance into internal circuit by three wiring of ABC of thermal resistance, thereby increased to a certain extent the reliability of whole mimic channel; The self-heating property problem that the constant current source long time loading causes in measured resistance when also greatly reducing the traditional hot electrical resistance collection simultaneously.In this programme, what passage change-over switch UA1, UB1 and UC1 etc. selected is light coupling relay, and this electrical isolation for the mimic channel in the whole measuring system and digital circuit provides possibility, thereby has greatly improved the reliability of whole measuring system.
The reference resistance commutation circuit as shown in Figure 5.Wherein, resistance R 0 is reference resistance; as the gating signal CS1 that disconnects all passages～CSx and during gating S5; the electric current I of constant current source flows into RO through US1-6, US1-5; and flow through protective resistance R10 through US1-7 and US1-8 and return constant current seedbed AGND, follow-up analog quantity conditioning and the change-over circuit of simultaneously T1 and T2 pin access records reference voltage U
0Because U
0/ R
0=U
RTDX/ R
TdxSo=I is R
TDx=R
0* U
RTDX/ U
0This shows that the size that needn't determine concrete constant current source I also can record thermal resistance R
TDxValue (x be respective channel numbering), thereby calculate R
xCorresponding temperature value; In other words, as long as measuring thermal resistance R
TDxDuring with measuring basis resistance R 0 constant current source I is consistent and just can guarantees the precision measured, this just can weaken the requirement to resistance R 7 among resistance R among Fig. 12, R3 and R4 and Fig. 2, also can slacken the variation of environment temperature to the impact of measuring accuracy simultaneously.
Claims (3)
1. a single constant current source Multi-channel hot resistance measuring system comprises constant-current source circuit, reference resistance sample circuit and thermal resistance metering circuit; The output terminal of described constant-current source circuit connects respectively the current input terminal of reference resistance sample circuit and the input end of thermal resistance metering circuit; The reference voltage voltage input end of thermal resistance metering circuit connects the voltage output end of described reference resistance sample circuit; The output terminal of described thermal resistance metering circuit is measured resistance R
TDxMeasuring junction;
It is identical and parallel with one another a plurality of to it is characterized in that described thermal resistance metering circuit comprises; Described constant-current source circuit comprises the folk art term reference voltage source circuit;
Described folk art term reference voltage source circuit comprises resistance R 1, R2, R3 and R4, stabilivolt Z1 and two-way switch U1A, U1B; After resistance R 2, R3 and R4 were cascaded first successively, in parallel with stabilivolt Z1 again, the cathode terminal of stabilivolt Z1 connected R2, and the anode tap of Z1 connects R4; One end of described resistance R 1 connects power supply AVCC end, and the other end connects the cathode terminal of stabilivolt Z1; Between the end contact resistance R2 and R3 of described two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1A is S1; Between the other end contact resistance R4 and R3 of two-way switch U1A, the other end is output signal AVCC2 end, and the switch control end of U1B is S2; S1 end and S2 end are not gating simultaneously; The cathode terminal of described stabilivolt Z1 connects its working power AVCC1 end, the anode tap ground connection of Z1;
Described constant-current source circuit comprises resistance R 5, R6 and R7, amplifier OP1 and triode Q1; One end of resistance R 7 connects power supply AVCC end, the emitter of other end connecting triode Q1; One end of resistance R 5 connects the emitter of Q1, and the other end connects the negative input end of amplifier OP1, and the positive input terminal of OP1 connects described output signal AVCC2 end; The output terminal of amplifier OP1 is by the collector of resistance R 6 connecting triode Q1; The collector of triode Q1 is as the current output terminal of this constant-current source circuit.
2. a kind of single constant current source Multi-channel hot resistance measuring system according to claim 1 is characterized in that in the described thermal resistance metering circuit any is single channel thermal resistance commutation circuit; For any single channel thermal resistance commutation circuit, comprise resistance R Ax, RBx, RCx, RDx, REx, RFx and RGx, two-way change-over switch UAx and UBx, and single channel change-over switch UCx; The corresponding channel B of measuring of described UAx, the corresponding channel C of measuring of UBx, the corresponding passage A that measures of UCx;
Described single channel change-over switch UCx is light coupling relay, and its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of light coupling relay, and the 4th, 6 pins are corresponding output terminal;
Described two-way change-over switch UAx is identical with UBx, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
The 2nd pin of described UCx connects respectively the 4th pin of described UAx and UBx, and interface channel is selected signal CSx end;
The 1st pin of described UCx connects power supply VCC end by resistance R Fx; The 1st pin of described UAx connects the VCC end by resistance R Gx;
The 1st pin of described UBx selects pin to connect corresponding selection signal as measuring channel B, and the 3rd pin of UBx selects pin to connect corresponding selection signal as measuring channel C;
The 6th pin of described UAx connects the sampled voltage of reference resistance, and the 4th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, consist of to measure passage A;
The 7th pin of described UAx connects the current output terminal of constant current source, and the 8th pin connects tested thermal resistance R by resistance R Ax
TDxAn end, namely be connected to and measure passage A;
The 5th pin ground connection of described UAx, the 6th pin connects tested thermal resistance R by resistance R Cx
TDxThe other end, consist of to measure channel B;
The 7th pin of described UBx connects the sampled voltage of reference resistance, and the 8th pin connects tested thermal resistance R by resistance R Dx
TDxThe other end, namely be connected to the measurement channel B;
The 6th pin of described UBx connects the sampled voltage of reference resistance, and the 5th pin connects tested thermal resistance R by resistance R Ex
TDxThe other end, consist of to measure channel C.
3. a kind of single constant current source Multi-channel hot resistance measuring system according to claim 1 and 2 is characterized in that described reference resistance sample circuit is the reference resistance commutation circuit, and it comprises resistance R 8, R9, R10 and R0, two two-way change-over switch US1 and US2;
Described resistance R 0 is reference resistance; Two-way change-over switch US1 is identical with US2, and they all are to be made of two light coupling relay, for arbitrary two-way change-over switch, its 1st, 2 pin is respectively anode tap and the cathode terminal of the luminotron of the first light coupling relay, and the 7th, 8 pins are corresponding output terminal; 3rd, 4 pins are respectively anode tap and the cathode terminal of the luminotron of the second light coupling relay, and the 5th, 6 pins are corresponding output terminal;
One end of described resistance R 0 connects the 5th pin of two-way change-over switch US1 and the 7th pin of US2, and the other end connects the 7th pin of US1 and the 5th pin of US2;
The 6th pin of described US1 is the Constant current input end; The 8th pin of one termination US1 of resistance R 10, other end connecting analog ground AGND;
The 8th pin of described US2 and the 6th pin of US2 are as voltage sample pin on the R0 resistance, for follow-up analog quantity sample circuit;
One end of described resistance R 8 connects power supply VCC end, and the other end connects the 1st pin of US1; The 2nd pin of US1 and the 3rd pin of US1 are shorted together, and the 4th pin of US1 is for selecting signal S5 input end; Resistance R 9 one ends connect power supply VCC end, and the other end connects the 1st pin of US2, and the 2nd pin of US2 and the 3rd pin of US2 are shorted together, and the 4th pin of US2 is for selecting signal S5 input end.
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| CN 201220215855 CN202648823U (en) | 2012-05-14 | 2012-05-14 | Single constant current source and multichannel thermal resistance measuring system |
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| CN 201220215855 CN202648823U (en) | 2012-05-14 | 2012-05-14 | Single constant current source and multichannel thermal resistance measuring system |
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| CN (1) | CN202648823U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103644975A (en) * | 2013-12-17 | 2014-03-19 | 深圳市汇川控制技术有限公司 | Multichannel temperature acquisition device |
| CN109738087A (en) * | 2019-03-07 | 2019-05-10 | 王成 | Multichannel three-wire system thermal resistance measuring system and method |
| CN109991295A (en) * | 2019-04-29 | 2019-07-09 | 福建海纳欣生物科技有限公司 | A kind of intelligent pH combination electrode and its implementation with temperature drift self-regulation |
-
2012
- 2012-05-14 CN CN 201220215855 patent/CN202648823U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103644975A (en) * | 2013-12-17 | 2014-03-19 | 深圳市汇川控制技术有限公司 | Multichannel temperature acquisition device |
| CN109738087A (en) * | 2019-03-07 | 2019-05-10 | 王成 | Multichannel three-wire system thermal resistance measuring system and method |
| CN109738087B (en) * | 2019-03-07 | 2023-12-19 | 深圳市拓普瑞电子有限公司 | Multichannel three-wire system thermal resistance measuring system and method |
| CN109991295A (en) * | 2019-04-29 | 2019-07-09 | 福建海纳欣生物科技有限公司 | A kind of intelligent pH combination electrode and its implementation with temperature drift self-regulation |
| CN109991295B (en) * | 2019-04-29 | 2023-12-08 | 福建海纳欣生物科技有限公司 | Intelligent pH composite electrode with temperature drift self-adjustment function and implementation method thereof |
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Address after: 211102, No. 199, Ting Ting West Road, Jiangning Economic Development Zone, Jiangning District, Jiangsu, Nanjing Patentee after: NANDA AUTOMATION TECHNOLOGY JIANGSU CO., LTD. Address before: 211102, No. 199, Ting Ting West Road, Jiangning Economic Development Zone, Jiangning District, Jiangsu, Nanjing Patentee before: Nanda Automation Technology Jiangsu Co., Ltd. |
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