CN-114942347-B - Wide-range low-dropout current measurement circuit

CN114942347BCN 114942347 BCN114942347 BCN 114942347BCN-114942347-B

Abstract

The invention belongs to the technical field of circuit measurement, and discloses a wide-range low-voltage-difference current measurement circuit which comprises a microprocessor, a sampling resistor R0, an output amplifier U7 and a plurality of shunt circuits connected in parallel, wherein each shunt circuit comprises a sampling resistor, an output amplifier, an automatic shunt regulating module and a shunt gate, one end of the sampling resistor R0 is connected with a current input end, the other end of the sampling resistor is connected with an input end of the output amplifier, two input ends of the automatic shunt regulating module are respectively connected with the current input end and a comparison voltage in each shunt circuit, the output end of the automatic shunt regulating module is connected with a control end of a shunt gate, one end of the shunt gate is connected with the current input end, the other end of the shunt gate is connected with one end of the sampling resistor, the other end of the sampling resistor is grounded, one end of the sampling resistor is connected with the input end of the output amplifier, and the output end of the output amplifier is connected with the microprocessor. The invention can realize the measurement requirement of high-speed wide-range current.

Inventors

CUI JIAN
WANG RUI
HU YAJUN
YAN JIANGUO
XIA CHUNQUAN

Assignees

青岛东软载波智能电子有限公司
青岛东软载波智能电子有限公司

Dates

Publication Date: 20260421
Application Date: 20220607
Priority Date: 20220607

Claims (10)

1. The wide-range low-voltage difference current measurement circuit comprises a sampling resistor R0, wherein one end of the sampling resistor R0 is connected with a current input end, and the other end of the sampling resistor R0 is connected with a current output end; the automatic shunt regulator is characterized by further comprising a microprocessor and a plurality of shunt circuits which are connected in parallel, wherein each shunt circuit is connected with a sampling resistor R0 in parallel, each shunt circuit comprises a sampling resistor, an automatic shunt regulator module and a shunt gate, the sampling resistors in each shunt circuit are divided into R1-RN, N represents the number of the shunt circuits, the resistance value of each sampling resistor meets the condition that R0> R1> Rn > RN, one input end of each automatic shunt regulator module is connected with a current input end, the other input end of each automatic shunt regulator module is connected with a comparison voltage, the output end of each automatic shunt regulator module is connected with a control end of each shunt gate, one end of each shunt gate is connected with a current input end, the other end of each automatic shunt regulator module is connected with one end of each sampling resistor, and the other end of each sampling resistor is connected with a current output end; one end of each sampling resistor is connected with the input end of the microprocessor through an output amplifier; The microprocessor is used for judging the states of the shunt gates according to the output voltages of the sampling resistors, and superposing the currents flowing through the sampling resistors of all the started shunt circuits so as to calculate the current value to be measured.
2. The wide-range low dropout current measurement circuit according to claim 1, wherein the comparison voltage of the connection of the automatic shunt regulator module corresponding to the sampling resistor Rn is smaller than the comparison voltage of the connection of the automatic shunt regulator module corresponding to the sampling resistor rn+1.
3. The wide-range low dropout current measurement circuit according to claim 1, wherein said sampling resistor in each shunt circuit satisfies the following condition: R n /R n+1 =Y,n=0......N; Wherein Y represents a proportionality constant greater than 1, and R n and R n+1 represent the resistance values of the sampling resistor Rn and the sampling resistor rn+1, respectively.
4. A wide range low dropout current measurement circuit according to claim 3, wherein Y has a value of 10.
5. The wide-range low dropout current measurement circuit according to claim 1, further comprising an analog-to-digital converter, wherein one end of each sampling resistor is connected to one of the output amplifiers, and the analog-to-digital converter is configured to perform analog-to-digital conversion on an output voltage of each output amplifier and send the output voltage to the microprocessor.
6. The wide-range low dropout current measurement circuit according to claim 5, wherein the amplification factors of the output amplifiers are the same.
7. The wide-range low dropout current measurement circuit according to claim 1, wherein each of the shunt gates includes one or more field effect transistors having gates connected to the output of the corresponding automatic shunt regulator module.
8. The wide-range low dropout current measurement circuit according to claim 1, wherein said automatic shunt regulator module is an operational amplifier.
9. The wide-range low dropout current measurement circuit according to claim 5, wherein said microprocessor determines the state of each of the shunt gates according to the output voltage of said analog-to-digital converter, and further calculates the current value by: S1, judging whether output voltage V0 corresponding to a sampling resistor R0 is smaller than Vth T, if yes, current I=V0/R 0 to be detected, and if not, entering a step S2, wherein T represents a safety coefficient; S2, judging whether output voltage V1 corresponding to the sampling resistor R1 is smaller than Vth T, if yes, determining current I= (V0/R 0 +V1/R 1 ) to be detected, and if not, entering step S3; S3, judging whether the output voltage V2 corresponding to the sampling resistor R2 is smaller than Vth T, if so, determining the current I= (V0/R 0 +V1/R 1 +V2/R 2 ) to be detected, otherwise, entering a step S4; ...... Sn, judging whether the output voltage Vn corresponding to the sampling resistor Rn is smaller than Vth T, if so, determining the current to be measured Wherein, the method comprises the steps of, n=0. N; R i represents the resistance of the sampling resistor Ri, i=0......n, vth represents the maximum sampling voltage drop of the wide range low dropout current measurement circuit.
10. The wide-range low dropout current measurement circuit according to claim 1, wherein said output amplifier has a non-inverting input connected to a near-current input of a corresponding sampling resistor, an inverting input connected to ground via a resistor, and a feedback resistor connected between the output and the inverting input.

Description

Wide-range low-dropout current measurement circuit Technical Field The invention relates to the technical field of current measurement, in particular to a current detection circuit with wide range and low voltage difference and a measurement method thereof. Background As technology advances, electronic devices have become lower in power consumption, which may be on the nanoampere level at low power consumption, but may be on the ampere level at high power consumption. For measuring such current, a wide-range analog-to-digital converter is required, for example, 30-bit ADC is required to realize nA-a span current measurement, no ADC with such high bit number is available on the market, and as the number of bits of the ADC conversion result increases, the conversion time of the ADC is longer, so that it is impossible to realize high-speed sampling of the wide-range current by using one sampling resistor. In addition, when some sensor physical quantity detection is realized, current change is large, and high-precision measurement of wide-range current is also required. The existing resistance switching schemes are realized by judging that the measuring result exceeds the measuring range and switching the sampling resistor through a pin, the mode needs program execution cooperation of the processor, the switching time cannot be fast, and if the current changes severely, the acquired data are invalid and cannot reflect the actual change of the current. In addition, the plurality of switches and resistors are connected in parallel, the more the number of sampling resistor stages is, the larger the corresponding number of switching stages is, the larger the sampling voltage drop is, and the field with strict requirements on the sampling voltage drop cannot be adapted. Disclosure of Invention In order to meet the actual requirements in the technical field of current measurement, the invention overcomes the defects existing in the prior art, and aims to solve the technical problem of providing a current detection circuit with wide range and low voltage difference so as to improve the range and the accuracy of current measurement. In order to solve the technical problems, the invention adopts the technical scheme that the wide-range low-voltage-difference current measurement circuit comprises a sampling resistor R0, a microprocessor and a plurality of shunt circuits connected in parallel, wherein each shunt circuit comprises a sampling resistor, an automatic shunt regulating module and a shunt gate, the sampling resistor in each shunt circuit is divided into R1-RN, N represents the number of the shunt circuits, the resistance value of each shunt resistor meets the condition that R0> R1> Rn > RN, and the output end of the output amplifier is connected with the microprocessor; in each shunt circuit, one input end of the automatic shunt regulating module is connected with a current input end, the other input end of the automatic shunt regulating module is connected with a comparison voltage, the output end of the automatic shunt regulating module is connected with the control end of the shunt gate, one end of the shunt gate is connected with the current input end, the other end of the shunt gate is connected with one end of the sampling resistor, and the other end of the sampling resistor is connected with the current output end; one end of each sampling resistor is connected with the input end of the microprocessor; the microprocessor is used for judging the states of the shunt gates according to the output voltages of the sampling resistors, and further calculating the current value to be measured. The comparison voltage connected with the automatic resistance shunt regulating module corresponding to the sampling resistor Rn is smaller than the comparison voltage connected with the automatic resistance shunt regulating module corresponding to the sampling resistor Rn+1. Further, the sampling resistor satisfies the following condition: Rn/Rn+1=Y,n=0......N; Wherein Y represents a proportionality constant greater than 1, and R n and R n+1 represent the resistance values of the sampling resistor Rn and the sampling resistor rn+1, respectively. Further, the value of Y is 10. Further, the wide-range low-dropout current measurement circuit further comprises an analog-to-digital converter and n+1 output amplifiers, one end of each sampling resistor is connected with one output amplifier respectively, and the analog-to-digital converter is used for performing analog-to-digital conversion on output voltage of each output amplifier and then sending the output voltage to the microprocessor. Further, the amplification factors of the respective output amplifiers are the same. Further, in each shunt circuit, the shunt gate includes one or more field effect transistors, and the gate of each field effect transistor is connected to the output end of the corresponding automatic shunt adjustment module. Further, the automatic shunt regu