CN215066929U - Current detection system - Google Patents
Current detection system Download PDFInfo
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- CN215066929U CN215066929U CN202120841675.4U CN202120841675U CN215066929U CN 215066929 U CN215066929 U CN 215066929U CN 202120841675 U CN202120841675 U CN 202120841675U CN 215066929 U CN215066929 U CN 215066929U
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Abstract
The utility model discloses a current detection system, which comprises a range selection module, a control module, a shunt resistance module, a voltage amplification module and an analog-to-digital conversion module; the shunt resistance module comprises a first input end, a second input end and a first output end; the first input end is used for being connected to one end of a load, and the other end of the load is grounded; the output end of the range selection module is connected with the input end of the control module, the output end of the control module is connected with the second input end, the first output end is connected with the input end of the voltage amplification module, the output end of the voltage amplification module is connected with the input end of the analog-to-digital conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the control module. The utility model has the characteristics of measuring accuracy is high, circuit low cost moreover. The utility model discloses can the wide application in current detection technical field.
Description
Technical Field
The utility model relates to a current detection technical field especially relates to a current detection system.
Background
In the prior art, when measuring current flowing through a circuit to be measured, instruments such as a multimeter are generally adopted for implementation. The universal meter utilizes ohm's law's rationale to measure current, during the measurement, connects the universal meter in the circuit that awaits measuring in series, and when the current that awaits measuring flows through the universal meter, can produce a sampling voltage at the both ends of the sampling resistance in the universal meter, utilizes the resistance of this sampling voltage and sampling resistance, alright in order to confirm the current of this circuit that awaits measuring.
In fact, since the resistance value of the multimeter itself exists, the resistance value has a great influence on the accuracy of current measurement.
In order to solve the problem of low accuracy, a professional detection instrument can be used for measurement, however, the professional detection instrument usually has the disadvantages of high price and poor portability.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model aims to provide a: a current sensing system is provided.
The utility model adopts the technical proposal that:
a current detection system comprises a range selection module, a control module, a shunt resistance module, a voltage amplification module and an analog-to-digital conversion module;
the shunt resistance module comprises a first input end, a second input end and a first output end;
the first input end is used for being connected to one end of a load, and the other end of the load is grounded;
the output end of the range selection module is connected with the input end of the control module, the output end of the control module is connected with the second input end, the first output end is connected with the input end of the voltage amplification module, the output end of the voltage amplification module is connected with the input end of the analog-to-digital conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the control module.
Further, the range selection module comprises a first key, a second key and a third key.
Further, the shunt resistance module comprises a resistance selection unit and a resistance unit;
the input end of the resistance selection unit is connected with the output end of the control module, the output end of the resistance selection unit is connected with the input end of the resistance unit, and the output end of the resistance unit is connected with the input end of the voltage amplification module.
Furthermore, the current detection system also comprises an indicator light module, and the input end of the indicator light module is connected with the output end of the control module.
Furthermore, the current detection system also comprises a display module, and the input end of the display module is connected with the output end of the control module.
Further, the current detection system further comprises a power supply voltage monitoring module.
Further, the analog-to-digital conversion module comprises an analog-to-digital converter with the model number ADS 1115.
The utility model has the advantages that: the current to be measured of the load flows through the shunt resistance module, the voltage amplification module is used for measuring shunt voltage at two ends of the shunt resistance module, the current to be measured flowing through the load can be calculated by using the ohm law, the system cannot influence the measurement of the shunt voltage, and the shunt resistance measuring system has the advantages of being high in measuring accuracy and low in circuit cost.
Drawings
FIG. 1 is a schematic diagram of a circuit for measuring current using a multimeter under ideal conditions in the related art;
FIG. 2 is a schematic diagram of a circuit for measuring current with a multimeter in a practical situation according to the related art;
fig. 3 is a schematic diagram of a current detection system according to the present invention;
fig. 4 is a block diagram of a current detection system according to the present invention;
fig. 5 is a schematic circuit diagram of a range selection module of a current detection system according to the present invention;
fig. 6 is a schematic circuit diagram of a voltage amplifying module of the current detecting system according to the present invention;
fig. 7 is a schematic circuit diagram of a shunt resistance module of a current detection system according to the present invention;
fig. 8 is a schematic circuit diagram of a power supply voltage monitoring module of the current detection system of the present invention.
Detailed Description
This section will describe in detail the embodiments of the present invention, preferred embodiments of the present invention are shown in the attached drawings, which are used to supplement the description of the text part of the specification with figures, so that one can intuitively and vividly understand each technical feature and the whole technical solution of the present invention, but they cannot be understood as the limitation of the protection scope of the present invention.
In the present invention, if there is a description of directions (up, down, left, right, front and back), it is only for convenience of description of the technical solution of the present invention, and it is not intended to indicate or imply that the technical features indicated must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the utility model, the meaning of a plurality of is one or more, the meaning of a plurality of is more than two, and the meaning of more than two is understood as not including the number; the terms "above", "below", "within" and the like are understood to include the instant numbers. In the description of the present invention, if there is any description of "first" and "second" only for the purpose of distinguishing technical features, it is not to be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the precedence of the indicated technical features.
In the present invention, unless otherwise explicitly defined, the terms "set", "install", "connect", and the like are to be understood in a broad sense, and for example, may be directly connected or may be indirectly connected through an intermediate medium; can be fixedly connected, can also be detachably connected and can also be integrally formed; may be mechanically coupled, may be electrically coupled or may be capable of communicating with each other; either as communication within the two elements or as an interactive relationship of the two elements. The technical skill in the art can reasonably determine the specific meaning of the above words in the present invention by combining the specific contents of the technical solution.
The invention will be further explained and explained with reference to the drawings and the embodiments in the following description.
Referring to fig. 1 and 2, in current measurement using a multimeter, in an ideal state (without considering the influence of the multimeter itself), an ideal current I flows in a circuit to be measured1Comprises the following steps:
wherein R isLFor connecting to the equivalent resistance, U, of the circuit to be measured of a multimeterLIs RLThe voltage across the terminals.
When the influence of the multimeter per se is large, the actual current I flowing in the current2Comprises the following steps:
wherein, UUniversal meterFor the multimeter itself influencing the voltage, U'LThe multimeter influences the sum of the voltage occupied by the multimeter itself and the voltage across the circuit to be measured.
As can be seen from the above, the multimeter has a large effect on the poor accuracy of the current measurement.
In order to at least partially solve one of the above problems, the present invention provides a current detection system, referring to fig. 3, the basic implementation principle is as follows:
the load is a circuit to be measured connected to the current detection system, and its equivalent resistance is RloadIn the current detection system, a load is connected in series, and a current flowing through the load flows through a shunt resistor M, thereby generating a shunt voltage U across the shunt resistor MMAccording to the shunt voltage U, using ohm's lawMAnd the resistance R of the shunt resistor MMThe current I to be measured flowing through the load can be measuredM：
Referring to fig. 4, a current detection system of the present application includes a range selection module, a control module, a shunt resistance module, a voltage amplification module, and an analog-to-digital conversion module;
the shunt resistance module comprises a first input end, a second input end and a first output end;
the first input end is used for being connected to one end of a load, and the other end of the load is grounded;
the output end of the range selection module is connected with the input end of the control module, the output end of the control module is connected with the second input end, the first output end is connected with the input end of the voltage amplification module, the output end of the voltage amplification module is connected with the input end of the analog-to-digital conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the control module.
Specifically, the current I to be measured flowing through the loadMThe current flows into the shunt resistance module, the range selection module is used for inputting a range selection signal to the control module, the control module controls the shunt resistance module to provide a proper shunt resistance M according to the input range selection control signal, and the current I to be measuredMFlows through the shunt resistor M (i.e. the shunt resistor module in essence), and forms a shunt voltage U across the shunt resistor MMDue to the shunt voltage UMIs smaller, the voltage amplification module is used for amplifying the shunt voltage to obtain an amplified shunt voltage UM1Amplified shunt voltage UM1Is an analog voltage signal, and therefore, utilizes modulusThe conversion module converts the analog voltage signal into a digital voltage signal, i.e. an amplified digital shunt voltage UM2The digital voltage signal can enter the control module to be processed, and can be known by ohm's law, and finally, the current I to be measured calculated by the control moduleMThe size of (A) is as follows:
the control module comprises a single chip microcomputer U4 with the model number of ATMEGA328P, and in addition, the control module further comprises a USB download circuit, and the USB download circuit comprises a USB chip and is used for downloading programs.
From the above, the present application makes the current I to be measured of the load laod (circuit to be measured)MThe current I to be measured flowing through the load can be calculated by measuring the shunt voltage at the two ends of the shunt resistance module through the shunt resistance module and utilizing ohm's lawMCompared with a universal meter and other measuring instruments, the shunt voltage measuring device can occupy partial voltage, the shunt voltage measuring device cannot influence the measurement of shunt voltage, and the shunt voltage measuring device has the advantages of being high in measuring accuracy and low in circuit cost.
And the range selection module is used for inputting a signal for selecting a proper current range to the control module. In a specific embodiment, referring to fig. 5, the range selection module includes a plurality of keys, wherein a first key SW2 is used for providing nA-level range and inputting a key signal for selecting nA-level range to the control module; the second key SW3 is used for selecting the range of the mA level and inputting a key signal for selecting the range of the mA level to the control module; the third key SW4 is used to select the uA level range and to input a signal to the control module to select the uA level range. The control module receives a key signal input by the key module, namely, the control module triggers a control signal to control the shunt resistance module to select a proper shunt resistance.
And the voltage amplifying module is used for amplifying the voltage at the two ends of the shunt resistor M. Referring to fig. 6, the voltage amplification module includes an amplifier U5 with a model of MAX4238AUT, and the voltage amplification factor of the operational amplifier U5 is:
wherein R is13Is the resistance of a thirteenth resistor R13, R14Is the resistance of a fourteenth resistor R14, R15The resistance of the fifteenth resistor R15 can be adjusted by adjusting the resistances of the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 to make the amplification factor of the operational amplifier U5 be 100, so as to amplify the voltage across the shunt resistor M by 100 times to obtain the amplified shunt voltage U15M1。
When the voltage amplification multiple of the voltage amplification module is designed to be 100 times, the determination process of the resistance value of the corresponding shunt resistor M is as follows:
shunt resistor R with 1mV/mA measuring rangeMThen it is:
Shunt resistor R corresponding to range of 1mV/uAMThen it is:
Shunt resistor R with range of 1mV/nAMThen it is:
As a further optional implementation, the shunt resistance module includes a resistance selection unit and a resistance unit;
the input end of the resistance selection unit is connected with the output end of the control module, the output end of the resistance selection unit is connected with the input end of the resistance unit, and the output end of the resistance unit is connected with the input end of the voltage amplification module.
And the shunt resistance module is used for selecting a proper shunt resistance according to a control signal of the control module. Referring to fig. 7, the resistance unit includes a thirty-first resistor R31, an eighteenth resistor R18, and a twenty-fifth resistor R25 (referred to as sub-shunt resistors), and the resistance selection unit includes a first fet Q1, a second fet Q2, a third fet Q3, a fourth fet Q4, a fifth fet Q5, and a sixth fet Q6.
The process of selecting the appropriate shunt resistance M by the shunt resistance module is as follows:
the control module triggers the control signal to control the corresponding field effect tube to be opened according to the input signal of the range selection input by the range selection module, and the circuit current to be tested flows into the ground GND through the sub-shunt resistor.
When the first key SW2 is pressed down and the selected current range is nA, the control module sends a low level signal to the gate of the fourth field effect transistor Q4 and the gate of the fifth field effect transistor Q5, and sends a high level signal to the gate of the sixth field effect transistor Q6, at this time, the first field effect transistor Q1 is turned on, the current to be measured can only flow through the thirty-one resistor R31 and then enters the ground GND,
at this time, the sub-shunt resistance of the thirty-first resistance R31 is determined as the shunt resistance M;
when the second key SW3 is pressed down and the selected current range is mA, the control module sends a high level signal to the gate of the fifth field effect transistor Q5 and the gate of the sixth field effect transistor Q6, and sends a low level signal to the gate of the fourth field effect transistor Q4, then the first field effect transistor Q1 and the second field effect transistor Q2 are turned on, the current to be measured flows through the thirty-first resistor R31 and the eighteenth resistor R18 and then enters the ground GND, and at this time, the parallel resistance of the thirty-first resistor R31 and the eighteenth resistor R18 is determined as a shunt resistor M;
when the third key SW4 is pressed down and the selected current range is uA, the control module sends a high level signal to the gate of the fourth fet Q4 and the gate of the sixth fet Q6, and sends a low level signal to the gate of the fifth fet Q5, then the first fet Q1 and the third fet Q3 are turned on, and the current to be measured flows through the thirty-first resistor R31 and the twenty-fifth resistor R25 and then enters the ground GND, at this time, the parallel resistance of the thirty-first resistor R31 and the twenty-fifth resistor R25 is determined as the shunt resistor M.
In the present embodiment, the first fet Q1 is always in the on state, so that the voltage amplifying module detects the voltage at the node B, that is, the voltage across the shunt resistor M.
In a specific embodiment, the value of the thirty-first resistor R31 is R3110K Ω, the eighteenth resistor R18 takes the value R18The value of the twenty-fifth resistor R25 is 0.01 Ω25When 10 Ω, then:
nA measuring range, RM＝R31＝10KΩ；
mA range, RM＝R31//R18＝0.01Ω；
uA range, RM＝R31//R25＝9.99Ω。
As a further optional implementation manner, the current detection system further includes a display module, and an input end of the display module is connected to an output end of the control module. A display module for displaying the current I to be measuredMThe current value of (1). The display module adopts an OLED display screen.
As a further optional implementation manner, the current detection system further includes an indicator light module, and an input end of the indicator light module is connected with an output end of the control module.
Specifically, the indicator light module comprises a plurality of indicator lights for indicating the measuring range used when the current detection system measures the current. In a specific embodiment, a first indicator light, a second indicator light and a third indicator light are included to respectively indicate that the current measuring range is mA measuring range, uA measuring range and nA measuring range.
As a further optional implementation, the current detection system further includes a power supply voltage monitoring module, where the power supply voltage monitoring module is configured to monitor a dynamic change of the power supply voltage. Referring to fig. 8, the power supply voltage monitoring module includes a power supply voltage monitoring chip U8 with model number TPS3809L30DBVR and a power indicator LED8, and when the power supply voltage monitoring chip U8 of the TPS3809L30DBVR detects that the power supply voltage is powered down or is lower than the monitoring voltage by 5V, the power indicator LED8 is turned off.
Further as an optional implementation, the analog-to-digital conversion module includes an analog-to-digital converter of the model ADS 1115.
In a specific embodiment, the analog-to-digital conversion module uses an analog-to-digital converter of the type ADS1115 as a core chip, and the analog-to-digital converter has 16-bit resolution and has the characteristics of high precision and low power consumption.
The working principle of the utility model is as follows:
after the system is powered on, a signal for range selection is input through the range selection module, the control module triggers a corresponding control signal according to the input signal for range selection, so that the shunt resistance module is controlled to provide a proper shunt resistance, and meanwhile, the control module can trigger the control signal to control a corresponding indicator lamp of the indicator lamp module to light up, so that the current range adopted at present is indicated. The current that awaits measuring of load flows through the shunt resistance to form shunt voltage at shunt resistance both ends, this shunt voltage obtains enlarged digital shunt voltage through the processing of voltage amplification module and analog-to-digital conversion module, and control module utilizes the resistance of enlarged digital shunt voltage and shunt resistance to calculate the shunt current according to ohm's law, also is the current that awaits measuring, and the current value of the current that awaits measuring calculated still can send to show display module, and convenience of customers looks over the current value that awaits measuring of load in real time.
While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined by the appended claims.
Claims (7)
1. A current detection system is characterized by comprising a range selection module, a control module, a shunt resistor module, a voltage amplification module and an analog-to-digital conversion module;
the shunt resistance module comprises a first input end, a second input end and a first output end;
the first input end is used for being connected to one end of a load, and the other end of the load is grounded;
the output end of the range selection module is connected with the input end of the control module, the output end of the control module is connected with the second input end, the first output end is connected with the input end of the voltage amplification module, the output end of the voltage amplification module is connected with the input end of the analog-to-digital conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the control module.
2. The current sensing system of claim 1, wherein the range selection module comprises a first button, a second button, and a third button.
3. The current detection system according to claim 1, wherein the shunt resistance module comprises a resistance selection unit and a resistance unit;
the input end of the resistance selection unit is connected with the output end of the control module, the output end of the resistance selection unit is connected with the input end of the resistance unit, and the output end of the resistance unit is connected with the input end of the voltage amplification module.
4. The current sensing system of claim 1, further comprising an indicator light module, an input of said indicator light module being connected to an output of said control module.
5. The current sensing system of claim 1, further comprising a display module, wherein an input of said display module is connected to an output of said control module.
6. The current sensing system of claim 1, further comprising a supply voltage monitoring module.
7. The current sensing system of claim 1, wherein the analog-to-digital conversion module comprises an analog-to-digital converter model ADS 1115.
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|---|---|---|---|
| CN202120841675.4U CN215066929U (en) | 2021-04-22 | 2021-04-22 | Current detection system |
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| CN202120841675.4U CN215066929U (en) | 2021-04-22 | 2021-04-22 | Current detection system |
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| CN215066929U true CN215066929U (en) | 2021-12-07 |
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| CN202120841675.4U Active CN215066929U (en) | 2021-04-22 | 2021-04-22 | Current detection system |
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