CN112485494A - Current detection circuit based on triode - Google Patents

Current detection circuit based on triode Download PDF

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Publication number
CN112485494A
CN112485494A CN202011287696.2A CN202011287696A CN112485494A CN 112485494 A CN112485494 A CN 112485494A CN 202011287696 A CN202011287696 A CN 202011287696A CN 112485494 A CN112485494 A CN 112485494A
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resistor
triode
transistor
current
network
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张海宝
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Tianjin Jinhang Computing Technology Research Institute
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Tianjin Jinhang Computing Technology Research Institute
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/146Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/30Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

The invention discloses a current detection circuit based on a triode, which comprises a sampling resistor R1, a current limiting resistor R2, a current limiting resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R _ load, a capacitor C1, a capacitor C2, a triode Q1, a triode Q2 and a triode Q3. The sampling resistor is connected in series in a high-voltage side loop of an input power supply, then differential signals at two ends of the sampling resistor are respectively sent to an amplifying circuit formed by a plurality of PNP type triodes and resistors, the amplifying times of the amplifying circuit are set by resistance values in the circuit, an independent power supply is not needed, and a sampling output signal and the input power supply are grounded.

Description

Current detection circuit based on triode
Technical Field
The invention belongs to the technical field of current measurement, relates to a current detection circuit based on a triode, and particularly relates to a current sampling circuit consisting of a simple device triode and a resistor.
Background
The current measurement technology has wide application, and in many systems, the magnitude of current flowing in and out needs to be detected, and the magnitude of the current value is used as an input parameter of closed-loop control. Currently, the current detection mainly includes the following modes:
firstly, the method comprises the following steps: the special high-voltage side current detection chip mainly comprises a plurality of chips of foreign companies such as MAXIM, TI and the like, and the current home-made chips are few;
secondly, the method comprises the following steps: the sampling resistor adds the operational amplifier, and the circuit needs to provide an independent power supply for the operational amplifier;
thirdly, the method comprises the following steps: the Hall sensor is large in size, needs an independent power supply, and is a foreign imported chip.
The current detection circuit based on the triode adopts devices which are all basic semiconductors and resistance elements, has multiple brands of alternative devices in China and import, and has the advantages of simple circuit, high reliability and no need of an independent power supply.
Disclosure of Invention
Objects of the invention
The purpose of the invention is: the circuit does not need a separate power supply, and the used components are easy to obtain, and the circuit has high reliability and is easy to realize.
(II) technical scheme
In order to solve the above technical problem, the present invention provides a current detection circuit, which includes a sampling resistor R1, a current limiting resistor R2, a current limiting resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R _ load, a capacitor C1, a capacitor C2, a transistor Q1, a transistor Q2, and a transistor Q3; the left end of the sampling resistor R1 is connected with an input power supply, the right end of the sampling resistor R1 is grounded through a resistor R _ load, and a capacitor C1 is connected with the sampling resistor R1 in parallel; one end of the current limiting resistor R2 is connected with an input power supply, and the other end is connected with an emitting electrode of the triode Q1 and an emitting electrode of the triode Q3; one end of the current-limiting resistor R3 is connected with the right end of the sampling resistor R1 and the other end of the capacitor C1, and the other end of the current-limiting resistor R3 is connected with the emitting electrode of the triode Q2; the base of a triode Q1 is connected with the base of a triode Q2, the collector of a triode Q1 is connected with one end of a resistor R4, the collector of a triode Q2 is connected with one end of a resistor R5, the collector of a triode Q3 is connected with one end of a resistor R7, a lead between the base of the triode Q1 and the base of a triode Q2 is connected with one end of the resistor R4, the base of a triode Q3 is connected with one end of the resistor R5, and one end of a capacitor C2 is connected between the collector of the triode Q3 and one end of the resistor R7 and serves as an output voltage; the other end of the resistor R4, the other end of the resistor R5, the other end of the resistor R7 and the other end of the capacitor C2 are grounded.
The left end of the sampling resistor R1 is marked as a 1# network, the right end of the sampling resistor R1 is marked as a 2# network, a 3# network is marked between the other end of the current-limiting resistor R2 and the emitter of the triode Q1, a 4# network is marked between the other end of the current-limiting resistor R3 and the emitter of the triode Q2, a 7# network is arranged between the collector of the triode Q1 and one end of the resistor R4, a 5# network is arranged between the collector of the triode Q2 and one end of the resistor R5, and a 9# network is arranged between the collector of the triode Q3 and.
When a current flows through the sampling resistor R1, a voltage drop occurs across the sampling resistor R1, the voltage on the left side (1# network) of the sampling resistor R1 is higher than the voltage on the right side (2# network), and after passing through the current limiting resistor R2 and the current limiting resistor R3, the voltage on the 3# network is also higher than the voltage on the 4# network. Transistor Q1 is of the same type as transistor Q2, the bases of the two diodes are connected together, and since the voltage drops across the two transistors Veb are the same, transistor Q1 is initially on and transistor Q2 is off. When the transistor Q1 is turned on, the network # 7 is high, and the transistor Q2 is turned off, which results in the network # 5 being low through the resistor R5 to ground.
The base of the triode Q3 is connected to the No. 5 network, the emitter is connected to the No. 3 network, the No. 3 network is at high level, the No. 5 network is at low level, the triode Q3 is conducted at the moment, and current flows through the base of the triode Q3 from the No. 3 network and then enters GND through the resistor R5. As the transistor Q3 is turned on, the current through the current limiting resistor R2 increases, causing the voltage drop across the current limiting resistor R2 to increase until, as the voltage across the 3# network gradually approaches and equals the voltage across the 4# network, the transistor Q2 gradually turns on, causing the voltage across the 5# network to gradually increase, and the current through the base of the transistor Q3 to decrease until a stable equilibrium state is reached.
(III) advantageous effects
According to the current detection circuit based on the triode provided by the technical scheme, the adopted devices are basic semiconductors and resistance elements, the current domestic components can meet the use requirements, the device purchasing channel is reliable, and meanwhile, the circuit is simple, has strong voltage impact resistance, does not need an independent power supply and has high reliability.
Drawings
Fig. 1 is a schematic diagram of a current sensing circuit based on a triode according to the present invention.
Detailed Description
In order to make the objects, contents, and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.
Fig. 1 is a schematic diagram of the present invention, and the current detection circuit based on the triode of the present invention includes a sampling resistor R1, a triode, a current limiting resistor, and other components, wherein the sampling resistor R1 converts a current signal into a voltage signal, and the PNP triode plays an amplifying role to form a differential amplifier, and differentially amplifies voltages at two ends of the sampling resistor.
Specifically, the current detection circuit comprises a sampling resistor R1, a current-limiting resistor R2, a current-limiting resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R _ load, a capacitor C1, a capacitor C2, a triode Q1, a triode Q2 and a triode Q3; the left end of the sampling resistor R1 is connected with an input power supply, the right end of the sampling resistor R1 is grounded through a resistor R _ load, and a capacitor C1 is connected with the sampling resistor R1 in parallel; one end of the current limiting resistor R2 is connected with an input power supply, and the other end is connected with an emitting electrode of the triode Q1 and an emitting electrode of the triode Q3; one end of the current-limiting resistor R3 is connected with the right end of the sampling resistor R1 and the other end of the capacitor C1, and the other end of the current-limiting resistor R3 is connected with the emitting electrode of the triode Q2; the base of a triode Q1 is connected with the base of a triode Q2, the collector of a triode Q1 is connected with one end of a resistor R4, the collector of a triode Q2 is connected with one end of a resistor R5, the collector of a triode Q3 is connected with one end of a resistor R7, a lead between the base of the triode Q1 and the base of a triode Q2 is connected with one end of the resistor R4, the base of a triode Q3 is connected with one end of the resistor R5, and one end of a capacitor C2 is connected between the collector of the triode Q3 and one end of the resistor R7 and serves as an output voltage; the other end of the resistor R4, the other end of the resistor R5, the other end of the resistor R7 and the other end of the capacitor C2 are grounded.
The left end of the sampling resistor R1 is marked as a 1# network, the right end of the sampling resistor R1 is marked as a 2# network, a 3# network is marked between the other end of the current-limiting resistor R2 and the emitter of the triode Q1, a 4# network is marked between the other end of the current-limiting resistor R3 and the emitter of the triode Q2, a 7# network is arranged between the collector of the triode Q1 and one end of the resistor R4, a 5# network is arranged between the collector of the triode Q2 and one end of the resistor R5, and a 9# network is arranged between the collector of the triode Q3 and.
When a current flows through the sampling resistor R1, a voltage drop occurs across the sampling resistor R1, the voltage on the left side (1# network) of the sampling resistor R1 is higher than the voltage on the right side (2# network), and after passing through the current limiting resistor R2 and the current limiting resistor R3, the voltage on the 3# network is also higher than the voltage on the 4# network. Transistor Q1 is of the same type as transistor Q2, the bases of the two diodes are connected together, and since the voltage drops across the two transistors Veb are the same, transistor Q1 is initially on and transistor Q2 is off. When the transistor Q1 is turned on, the network # 7 is high, and the transistor Q2 is turned off, which results in the network # 5 being low through the resistor R5 to ground.
The base of the triode Q3 is connected to the No. 5 network, the emitter is connected to the No. 3 network, the No. 3 network is at high level, the No. 5 network is at low level, the triode Q3 is conducted at the moment, and current flows through the base of the triode Q3 from the No. 3 network and then enters GND through the resistor R5. As the transistor Q3 is turned on, the current through the current limiting resistor R2 increases, causing the voltage drop across the current limiting resistor R2 to increase until, as the voltage across the 3# network gradually approaches and equals the voltage across the 4# network, the transistor Q2 gradually turns on, causing the voltage across the 5# network to gradually increase, and the current through the base of the transistor Q3 to decrease until a stable equilibrium state is reached.
The specific circuit connection relationship of the circuit of the invention is as follows:
(1) the sampling resistor R1 is used for sampling a current signal, converting the current signal into a voltage signal, generating voltage drop at two ends of the sampling resistor R1, and the capacitor C1 is used for filtering the voltage signal at two ends of the sampling resistor R1, filtering out high-frequency interference signals and ensuring that the voltage signal at two ends of the sampling resistor R1 is relatively stable direct-current voltage. Two ends of the sampling resistor R1 are respectively connected to a current limiting resistor R2 and a current limiting resistor R3, the current limiting resistor R2 is used for limiting the current flowing through the base of the PNP triode Q1, and the current limiting resistor R3 is used for limiting the current flowing through the base of the PNP triode Q2.
(2) The base electrodes of the transistor Q1 and the transistor Q2 are connected together and then connected to the collector electrode of the transistor Q1, and the collector electrodes of the transistor Q1 and the transistor Q2 are grounded through a resistor R4 and a resistor R5 respectively.
(3) An emitter of the triode Q3 is connected to an emitter of the triode Q1, a base of the triode Q3 is connected to a collector of the triode Q2, a collector of the triode Q3 is grounded through a resistor R7 and a capacitor C2, and a collector voltage of the triode Q3 is an output signal of current sampling.
(4) When current passes through the resistor R1, the voltage of the left side (1# network) is higher than that of the right side (2# network), the voltage of the emitter (3# network) of the transistor Q1 at the initial moment after passing through the current limiting resistor R2 and the current limiting resistor R3 is higher than that of the emitter (4# network) of the transistor Q2, the voltage drop of Vbe is the same based on the same model of the transistor Q1 and the transistor Q2, and the base current of the transistor Q1 is higher than that of the transistor Q2 at the same time because the bases of the transistors Q1 and Q2 are connected to the same point. Considering the current amplification effect of the transistor, the current flowing through the collector of the transistor Q1 is much higher than the current flowing through the collector of the transistor Q2, which further causes the voltage over the resistor R4 to be higher than the voltage over the resistor R5.
(5) Since the voltage of the emitter of the transistor Q1 (3# network) is higher than the voltage above the resistor R4 and therefore higher than the voltage above the resistor R5, the base of the transistor Q3 has current flowing through it, according to the current amplification characteristic of the PNP transistor, the transistor Q3 allows current to pass through the emitter and collector, and finally current enters the resistor R7 and generates voltage, which flows through the current limiting resistor R2, increasing the voltage drop of the current limiting resistor R2, the larger the current, the higher the voltage drop of the current limiting resistor R2, until the voltage of the 3# network is equal to the voltage of the 4# network, at which time the transistor Q2 is turned on, and the voltages above the resistor R4 and the resistor 5 are also equal. That is, at this time, the voltages of the 3# network and the 4# network are equal, and the voltages of the 7# network and the 5# network are equal. The voltage drop across the sampling resistor R1 is equal to the voltage value of the current through the collector of transistor Q3 multiplied by the current limiting resistor R2, which current produces a voltage signal when flowing through resistor R7.
According to the technical scheme, the triode-based current detection circuit connects the sampling resistor in series in a high-voltage side loop of an input power supply, then differential signals at two ends of the sampling resistor are respectively sent to the amplifying circuit formed by a plurality of PNP type triodes and resistors, the amplification factor of the amplifying circuit is set by a resistance value in the circuit, the sampling circuit does not need an independent power supply, and a sampling output signal and the input power supply are grounded together.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A current detection circuit based on a triode is characterized by comprising a sampling resistor R1, a current limiting resistor R2, a current limiting resistor R3, a resistor R4, a resistor R5, a resistor R7, a resistor R _ load, a capacitor C1, a capacitor C2, a triode Q1, a triode Q2 and a triode Q3; the left end of the sampling resistor R1 is connected with an input power supply, the right end of the sampling resistor R1 is grounded through a resistor R _ load, and a capacitor C1 is connected with the sampling resistor R1 in parallel; one end of the current limiting resistor R2 is connected with an input power supply, and the other end is connected with an emitting electrode of the triode Q1 and an emitting electrode of the triode Q3; one end of the current-limiting resistor R3 is connected with the right end of the sampling resistor R1 and the other end of the capacitor C1, and the other end of the current-limiting resistor R3 is connected with the emitting electrode of the triode Q2; the base of a triode Q1 is connected with the base of a triode Q2, the collector of a triode Q1 is connected with one end of a resistor R4, the collector of a triode Q2 is connected with one end of a resistor R5, the collector of a triode Q3 is connected with one end of a resistor R7, a lead between the base of the triode Q1 and the base of a triode Q2 is connected with one end of the resistor R4, the base of a triode Q3 is connected with one end of the resistor R5, and one end of a capacitor C2 is connected between the collector of the triode Q3 and one end of the resistor R7 and serves as an output voltage; the other end of the resistor R4, the other end of the resistor R5, the other end of the resistor R7 and the other end of the capacitor C2 are grounded.
2. The triode based current detection circuit as claimed in claim 1, wherein the left end of the sampling resistor R1 is denoted as # 1 network, the right end is denoted as # 2 network, a # 3 network is denoted between the other end of the current limiting resistor R2 and the emitter of the triode Q1, a # 4 network is denoted between the other end of the current limiting resistor R3 and the emitter of the triode Q2, a # 7 network is arranged between the collector of the triode Q1 and one end of the resistor R4, a # 5 network is arranged between the collector of the triode Q2 and one end of the resistor R5, and a # 9 network is arranged between the collector of the triode Q3 and one end of the resistor R7.
3. The triode based current detection circuit of claim 2, wherein when current flows through the sampling resistor R1, a voltage drop is generated across the sampling resistor R1, the voltage on the left side of the sampling resistor R1 is higher than the voltage on the right side, and after passing through the current limiting resistor R2 and the current limiting resistor R3, the voltage on the # 3 network is higher than the voltage on the # 4 network.
4. The transistor-based current sense circuit of claim 3, wherein the transistor Q1, the transistor Q2, and the transistor Q3 are PNP transistors.
5. The transistor-based current sense circuit of claim 4, wherein the transistor Q1 and the transistor Q2 are of the same type, and wherein the bases of the two diodes are connected together, so that initially the transistor Q1 is on and the transistor Q2 is off, since the voltage drops of the two transistors Veb are the same; when the transistor Q1 is turned on, the network # 7 is high, and the transistor Q2 is turned off, which results in the network # 5 being low through the resistor R5 to ground.
6. The triode based current sense circuit of claim 5, wherein the base of the transistor Q3 is connected to the # 5 network, the emitter is connected to the # 3 network, the # 3 network is high, the # 5 network is low, when the transistor Q3 is turned on, current flows from the # 3 network through the base of the transistor Q3 and then through the resistor R5 to GND; the transistor Q3 is turned on, and the current flowing through the current limiting resistor R2 increases, so that the voltage drop generated across the current limiting resistor R2 also increases, until the voltage of the 3# network gradually approaches and equals the voltage of the 4# network, the transistor Q2 is gradually turned on, so that the voltage of the 5# network gradually increases, and the current flowing through the base of the transistor Q3 decreases until a stable equilibrium state is reached.
7. The transistor-based current sensing circuit as claimed in claim 6, wherein the sampling resistor R1 is configured to sample a current signal and convert the current signal into a voltage signal, and a voltage drop is generated across the sampling resistor R1, the capacitor C1 is configured to filter the voltage signal across the sampling resistor R1 and filter out high frequency interference signals, the sampling resistor R1 is connected across the current limiting resistor R2 and the current limiting resistor R3, the current limiting resistor R2 is configured to limit the current flowing through the base of the PNP transistor Q1, and the current limiting resistor R3 is configured to limit the current flowing through the base of the PNP transistor Q2.
8. The transistor-based current sense circuit of claim 7, wherein the bases of the transistor Q1 and the transistor Q2 are connected together and then to the collector of the transistor Q1, and the collectors of the transistor Q1 and the transistor Q2 are connected to ground through a resistor R4 and a resistor R5, respectively; an emitter of the triode Q3 is connected to an emitter of the triode Q1, a base of the triode Q3 is connected to a collector of the triode Q2, a collector of the triode Q3 is grounded through a resistor R7 and a capacitor C2, and a collector voltage of the triode Q3 is an output signal of current sampling.
9. The transistor-based current sensing circuit of claim 8, wherein the voltage at the emitter of the transistor Q1 is higher than the voltage at the top of the resistor R4 and higher than the voltage at the top of the resistor R5, and when the base of the transistor Q3 has current flowing through it, the current enters the resistor R7 and generates a voltage which flows through the resistor R2, increasing the voltage drop across the resistor R2, the voltage drop across the resistor R2 is higher the current is, until the voltage across the 3# network is equal to the voltage across the 4# network, and when the transistor Q2 is turned on, the voltages at the resistor R4 and the resistor R5 are equal.
10. Use of a triode based current sense circuit according to any of claims 1-9 in the field of current measurement technology.
CN202011287696.2A 2020-11-17 2020-11-17 Current detection circuit based on triode Pending CN112485494A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113740589A (en) * 2021-09-03 2021-12-03 北京迪赛奇正科技有限公司 Module power high-end current detection amplifying circuit

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CN201590941U (en) * 2010-01-11 2010-09-22 纵领电子(上海)有限公司 Lamp current sampling converting circuit of light adjusting electronic ballast
CN102081420A (en) * 2009-12-01 2011-06-01 延锋伟世通汽车电子有限公司 Current limiting regulated power supply with high precision
CN103049029A (en) * 2012-12-30 2013-04-17 青岛东软载波科技股份有限公司 Current-limiting circuit
CN103713181A (en) * 2013-12-30 2014-04-09 重庆华渝电气集团有限公司 Tiny current signal detecting device
CN203643497U (en) * 2013-12-24 2014-06-11 青岛伏科太阳能有限公司 Current detection circuit of photovoltaic system
CN108957100A (en) * 2018-07-27 2018-12-07 无锡雷利电子控制技术有限公司 A kind of current detection means

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102081420A (en) * 2009-12-01 2011-06-01 延锋伟世通汽车电子有限公司 Current limiting regulated power supply with high precision
CN201590941U (en) * 2010-01-11 2010-09-22 纵领电子(上海)有限公司 Lamp current sampling converting circuit of light adjusting electronic ballast
CN103049029A (en) * 2012-12-30 2013-04-17 青岛东软载波科技股份有限公司 Current-limiting circuit
CN203643497U (en) * 2013-12-24 2014-06-11 青岛伏科太阳能有限公司 Current detection circuit of photovoltaic system
CN103713181A (en) * 2013-12-30 2014-04-09 重庆华渝电气集团有限公司 Tiny current signal detecting device
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113740589A (en) * 2021-09-03 2021-12-03 北京迪赛奇正科技有限公司 Module power high-end current detection amplifying circuit

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Application publication date: 20210312