CN216160731U - Current sensor circuit based on sampling resistor - Google Patents
Current sensor circuit based on sampling resistor Download PDFInfo
- Publication number
- CN216160731U CN216160731U CN202122109805.8U CN202122109805U CN216160731U CN 216160731 U CN216160731 U CN 216160731U CN 202122109805 U CN202122109805 U CN 202122109805U CN 216160731 U CN216160731 U CN 216160731U
- Authority
- CN
- China
- Prior art keywords
- amplifier
- inductive
- current sensor
- detection lead
- sampling resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
The utility model provides a current sensor circuit based on a sampling resistor, which is characterized by comprising: the device comprises an amplifier U1, a positive electrode detection lead L1, a negative electrode detection lead L2 and n noninductive sampling resistors Rn; an anode detection port of the amplifier U1 is connected with the anode detection lead L1, a cathode detection port of the amplifier U1 is connected with the cathode detection lead L2, one end of each non-inductive sampling resistor Rn is connected with the cathode detection lead L2, the other end of each non-inductive sampling resistor Rn is connected with a pair of synchronous parallel switch devices Sn respectively, correspondingly, n pairs of parallel contacts are arranged on the anode detection lead L1, and each pair of parallel contacts corresponds to one synchronous parallel switch device Sn respectively; and the resistance values of the non-inductive sampling resistors Rn are subjected to equal ratio increasing or decreasing.
Description
Technical Field
The utility model belongs to the technical field of electronics, metering and testing, and particularly relates to a current sensor circuit based on a sampling resistor.
Background
A non-inductive resistor Rs is connected in series in a circuit where a current to be detected is located, when the resistance value of the resistor Rs is far smaller than the impedance of a loop to be detected, the resistor can be used as a loop current sampling resistor, and the voltage Vs at two ends of the resistor reflects the magnitude of the current I of the loop to be detected:
in order to reduce the influence of the introduction of the Rs on the tested loop, the Rs should be much smaller than the impedance of the tested loop, and the value of Vs is generally smaller. When Vs is small, the performance of the subsequent a/D converter cannot be fully exerted, and the current measurement accuracy cannot be guaranteed. In order to fully exert the performance of the a/D converter and ensure the measurement accuracy, it is necessary to amplify Vs to a level suitable for the input range of the a/D converter by a voltage amplifier, and then perform analog-to-digital conversion by the a/D converter.
The sampling resistor and the voltage amplifier form a current sensor circuit based on the sampling resistor, and conversion from current to be measured to voltage is realized. In order to adapt to the magnitude of different measured currents, the measuring range or measuring range of the current sensor should have certain adjusting capability. The measuring range or range of the current sensor based on the sampling resistor is adjusted by two methods: firstly, 1 non-inductive resistor with fixed resistance is used, the amplification factor A of the amplifier is designed to be adjustable in a stepping mode, and proper gears are selected according to requirements; secondly, preparing a plurality of non-inductive resistors with different resistance values, fixing the amplification factor A of the amplifier, and selecting a resistor with a proper resistance value according to requirements, namely changing the size of the sampling resistor Rs. The first method is convenient to implement and only needs one non-inductive resistor. The main disadvantage of this method is that when the amplification a of the subsequent amplifier is changed, the bandwidth of the amplifier is usually undesirably reduced as the amplification increases. The second method needs a switch or a relay to switch the sampling resistor, but the switch or the relay inevitably has contact resistors, and the current of the detected loop flows through the contact resistors to generate voltage drop, thereby causing sampling error, and the problem is more prominent in large range, and the larger loop current generates larger voltage drop on the contact resistors.
SUMMERY OF THE UTILITY MODEL
The present invention proposes a current sensor circuit based on a sampling resistor for overcoming the above mentioned problems or at least partially solving or alleviating them.
A sampled resistance based current sensor circuit comprising: the device comprises an amplifier U1, a positive electrode detection lead L1, a negative electrode detection lead L2 and n noninductive sampling resistors Rn; an anode detection port of the amplifier U1 is connected with the anode detection lead L1, a cathode detection port of the amplifier U1 is connected with the cathode detection lead L2, one end of each non-inductive sampling resistor Rn is connected with the cathode detection lead L2, the other end of each non-inductive sampling resistor Rn is connected with a pair of synchronous parallel switch devices Sn respectively, correspondingly, n pairs of parallel contacts are arranged on the anode detection lead L1, and each pair of parallel contacts corresponds to one synchronous parallel switch device Sn respectively; and the resistance values of the non-inductive sampling resistors Rn are subjected to equal ratio increasing or decreasing.
The sampling resistor based current sensor circuit of the present invention also has the following optional features.
Optionally, the synchronous parallel switch device Sn is a double pole switch.
Optionally, the synchronous parallel switch device Sn is a relay.
Optionally, the non-inductive sampling resistor Rn is a single fixed value non-inductive resistor or an equivalent resistor formed by connecting a plurality of fixed value non-inductive resistors in parallel.
Optionally, an amplifier input protection circuit C1 is further connected to the positive detection port of the amplifier U1.
Optionally, an amplifier zeroing circuit C2 is further connected to the amplifier U1.
The current sensor circuit based on the sampling resistor can enable a measured current signal to only flow through the first contact of the synchronous parallel switch device, the sampling signal is sent to the backward-stage amplifier through the second contact, the sampling signal does not contain the voltage drop of the measured current on the contact of the synchronous parallel switch device, the amplifier usually has high input impedance, the input current is extremely small, the voltage drop of the contact of the synchronous parallel switch device caused by the input current of the amplifier is very small, and the measurement error caused by the voltage drop is very small.
Drawings
Fig. 1 is a schematic diagram of a current sensor based on a sampling resistor according to the present invention.
Detailed Description
Example 1
Referring to fig. 1, an embodiment of the present invention provides a current sensor circuit based on a sampling resistance, including: the device comprises an amplifier U1, a positive electrode detection lead L1, a negative electrode detection lead L2 and n noninductive sampling resistors Rn; an anode detection port of the amplifier U1 is connected with the anode detection lead L1, a cathode detection port of the amplifier U1 is connected with the cathode detection lead L2, one end of each non-inductive sampling resistor Rn is connected with the cathode detection lead L2, the other end of each non-inductive sampling resistor Rn is connected with a pair of synchronous parallel switch devices Sn respectively, correspondingly, n pairs of parallel contacts are arranged on the anode detection lead L1, and each pair of parallel contacts corresponds to one synchronous parallel switch device Sn respectively; and the resistance values of the non-inductive sampling resistors Rn are subjected to equal ratio increasing or decreasing.
IN fig. 1, an amplifier U1 is provided with a model number of OP37GS, a positive detection port + IN of the amplifier U1 is connected with a positive detection lead L1 through a safety resistor R5, a negative detection port-IN of the amplifier U1 is connected with a negative detection lead L2 through a safety resistor R6, resistors R7 are connected with negative detection ports-IN and OUT of the amplifier U1, and the resistances of R5, R6 and R7 are 100 Ω, 100 Ω and 9.9k Ω respectively. The V-port of amplifier U1 is connected to a negative 15V supply VEE and the V + port of amplifier U1 is connected to a positive +15V supply VDD.
The current sensor circuit based on the sampling resistor in the utility model in the figure 1 has four gears, the sensitivities are respectively 1V/A, 10V/A, 100V/A and 1000V/A, the measuring ranges are respectively 10A, 1A, 0.1A and 10mA, and the corresponding measuring ranges are respectively-10A, -1A, -0.1A and-10 mA. The noninductive sampling resistors Rn are four noninductive sampling resistors R1, noninductive sampling resistors R2, noninductive sampling resistors R3 and noninductive sampling resistors R4, the resistance values are 0.01 Ω, 0.1 Ω, 1 Ω and 10 Ω respectively, and a synchronous parallel switch device S1, a synchronous parallel switch device S2, a synchronous parallel switch device S3 and a synchronous parallel switch device S4 are arranged between the noninductive sampling resistors R1, the noninductive sampling resistors R2, the noninductive sampling resistors R3 and the noninductive sampling resistors R4 and parallel contacts on the positive detection lead L1 respectively.
When the current is detected, a measurement gear is set according to an estimated value of the detected current, for example, 1A, a non-inductive sampling resistor R2 is adopted, a terminal I + of a positive electrode detection lead L1 and a terminal I-of a negative electrode detection lead L2 are connected to a detected loop, the detected current I flows through a contact S2_1 of a synchronous parallel switch device S2 and a corresponding non-inductive sampling resistor R2, voltage drop is generated at two ends of the non-inductive sampling resistor R2, but the contact S2_2 of the synchronous parallel switch device S2 crosses the contact S2_1 of the synchronous parallel switch device S2, only the voltage of the non-inductive sampling resistor R2 is collected and sent to a subsequent amplifier, and the subsequent amplifier is amplified by a certain multiple to form a sensor output voltage Vo.
It is clear that the voltage drop of the measured current at contact S2_1 of the synchronous parallel switch device S2 is effectively subtracted. Since the voltage signal amplifier input current is small, the voltage drop generated at the contact S2_1 is also small and can be ignored when the sampling accuracy requirement is not particularly high. The same effect as described above can be obtained when other gears are selected. Because the amplification factor of the amplifier is fixed, the bandwidth of the amplifier cannot change along with the change of the measurement gear.
Example 2
Referring to fig. 1, in embodiment 1, the synchronous parallel switch device Sn is a two-pole switch.
When the synchronous parallel switch device Sn adopts a double-pole switch, the common end of each double-pole switch is connected with the non-inductive sampling resistor Rn, two contact ends of the double-pole switch are respectively contacted with parallel contacts on the positive detection lead L1, so that two contact ends Sn _1 and Sn _2 of the double-pole switch are respectively connected with and detect the current and the voltage on the non-inductive sampling resistor Rn, wherein the contact end Sn _1 is crossed when the Sn _2 detects the voltage, and the sampling signal does not contain the voltage drop of the detected current on the contacts of the double-pole switch.
Example 3
In embodiment 1, the synchronous parallel switch device Sn is a relay.
And a relay is adopted as the synchronous parallel switch device Sn, six pins are arranged in the relay, two pins are connected with the control coil, one end of the remaining two pairs of pins is connected with one end of the non-inductive sampling resistor Rn together, and the other ends of the remaining two pairs of pins are respectively connected with corresponding parallel contacts on the positive detection lead L1.
Example 4
Referring to fig. 1, in addition to embodiment 1, the non-inductive sampling resistor Rn is a single fixed value non-inductive resistor or an equivalent resistor formed by connecting a plurality of fixed value non-inductive resistors in parallel.
For example, in fig. 1, the non-inductive sampling resistor R1 has an equivalent resistance of 0.01 Ω, and is formed by connecting 10 non-inductive sampling resistors R _1, R _2, R _3, R _4, R _5, R _6, R _7, R _8, and R _9 having a resistance of 0.1 Ω in parallel with a non-inductive sampling resistor R _ 10.
Example 5
Referring to fig. 1, in addition to embodiment 1, an amplifier input protection circuit C1 is further connected to the positive detection port of the amplifier U1.
The amplifier input protection circuit C1 comprises a ring-shaped circuit which is clockwise connected with a diode D2, a diode D1, a diode D3 and a diode D4, the models of the four diodes are all 1N4149, the diode D2 and the diode D1 are connected with +15V voltage VDD through a resistor R8 with the resistance value of 10k omega, the diode D1 and the diode D3 are grounded, the diode D3 and the diode D4 are connected with-15V voltage VEE through a resistor R9 with the resistance value of 10k omega, and an anode detection port + IN of an amplifier U1 is connected between the diode D2 and the diode D4 through a lead.
Example 6
Referring to fig. 1, in addition to embodiment 1, an amplifier nulling circuit C2 is connected to the amplifier U1.
R10, R11 and R12 are connected in series between two VosTRIM ends of the amplifier U1, the resistance values of R10 and R12 are respectively 4.7k omega, the resistance value of R11 is 1k omega, R11 is a sliding resistor, and the sliding end of the sliding resistor is connected to a V + and 15V positive power supply VDD.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims. The components and structures of the present embodiments that are not described in detail are well known in the art and do not constitute essential structural elements or elements.
Claims (6)
1. A sampled resistance based current sensor circuit, comprising: the device comprises an amplifier U1, a positive electrode detection lead L1, a negative electrode detection lead L2 and n noninductive sampling resistors Rn; an anode detection port of the amplifier U1 is connected with the anode detection lead L1, a cathode detection port of the amplifier U1 is connected with the cathode detection lead L2, one end of each non-inductive sampling resistor Rn is connected with the cathode detection lead L2, the other end of each non-inductive sampling resistor Rn is connected with a pair of synchronous parallel switch devices Sn respectively, correspondingly, n pairs of parallel contacts are arranged on the anode detection lead L1, and each pair of parallel contacts corresponds to one synchronous parallel switch device Sn respectively; and the resistance values of the non-inductive sampling resistors Rn are subjected to equal ratio increasing or decreasing.
2. The sampled resistance based current sensor circuit of claim 1, wherein the synchronous parallel switch arrangement Sn is a two-pole switch.
3. The sampled resistance based current sensor circuit of claim 1, wherein the synchronous parallel switch device Sn is a relay.
4. The sampling resistor based current sensor circuit according to claim 1, wherein the non-inductive sampling resistor Rn is a single fixed value non-inductive resistor or an equivalent resistor formed by connecting a plurality of fixed value non-inductive resistors in parallel.
5. The sampled resistance based current sensor circuit of claim 1, wherein an amplifier input protection circuit C1 is further connected to the positive sense port of the amplifier U1.
6. The sampled resistance based current sensor circuit of claim 1, wherein an amplifier nulling circuit C2 is further coupled to said amplifier U1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122109805.8U CN216160731U (en) | 2021-09-02 | 2021-09-02 | Current sensor circuit based on sampling resistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122109805.8U CN216160731U (en) | 2021-09-02 | 2021-09-02 | Current sensor circuit based on sampling resistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216160731U true CN216160731U (en) | 2022-04-01 |
Family
ID=80841519
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122109805.8U Active CN216160731U (en) | 2021-09-02 | 2021-09-02 | Current sensor circuit based on sampling resistor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216160731U (en) |
-
2021
- 2021-09-02 CN CN202122109805.8U patent/CN216160731U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106990295A (en) | A kind of resistance measuring instrument and resistance measurement method | |
| EP2873979B1 (en) | Active current sensing circuit and measurement device | |
| EP2874310B1 (en) | Current sensing circuit | |
| CN217007520U (en) | Precision current sensor circuit based on sampling resistor | |
| US2360523A (en) | Electrical measuring apparatus | |
| CN216160731U (en) | Current sensor circuit based on sampling resistor | |
| CN206818800U (en) | A kind of resistance measuring instrument | |
| CN202994905U (en) | Resistance measuring circuit | |
| CN204044219U (en) | Voltage-measuring equipment | |
| CN103308878A (en) | On-site detection device for resistor divider in high-voltage direct current power transmission and transformation system | |
| CN116908588A (en) | High-reliability testing device for initiating explosive device electromagnetic valve | |
| CN201788222U (en) | AC-DC (alternating current-direct current) compatible isolated voltage sampling circuit | |
| US20130043892A1 (en) | Resistance measurement circuit | |
| CN116265963A (en) | Precision current sensor circuit based on sampling resistor | |
| TW201835581A (en) | Resistance measuring system and resistance measuring device includes a current detector, a standard resistor, a probe assembly and a signal processing unit | |
| CN210514584U (en) | Zinc oxide arrester live-line tester | |
| CN113514690A (en) | High-precision wide-range current measuring system | |
| CN204154856U (en) | Triode amplifies test circuit | |
| CN103823116A (en) | Self-checking type precision battery internal resistance instrument | |
| CN105548649A (en) | Potentiometer with six stepping discs | |
| CN219935966U (en) | High-precision high-current acquisition circuit supporting multi-gear switching | |
| RU2251116C1 (en) | Bridge device for measuring resistance of resistance transducers | |
| CN204065208U (en) | Potential difference meter | |
| CN109343645B (en) | Program-controlled power signal source output voltage multiplication circuit | |
| CN204044220U (en) | Small voltage measurement mechanism |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |