CN113702707A - Load impedance measuring circuit, system and electronic equipment - Google Patents
Load impedance measuring circuit, system and electronic equipment Download PDFInfo
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- CN113702707A CN113702707A CN202110897943.9A CN202110897943A CN113702707A CN 113702707 A CN113702707 A CN 113702707A CN 202110897943 A CN202110897943 A CN 202110897943A CN 113702707 A CN113702707 A CN 113702707A
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- G01—MEASURING; TESTING
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Abstract
The invention provides a load impedance measuring circuit, a system and electronic equipment, wherein the circuit comprises a main control circuit and a measuring circuit; the measuring circuit is used for connecting an external load; the output end of the main control circuit is used for being connected with the measuring circuit and the load respectively and supplying power to the measuring circuit and the load; the measuring end of the main control circuit is respectively connected with the two ends of the measuring circuit and used for acquiring signals required by load impedance measurement; the main control circuit is used for determining the impedance of the load according to the acquired signal. The measuring circuit of the invention has simple structure, can calculate the load impedance by only measuring one path of signal, and reduces the measuring error and the measuring cost.
Description
Technical Field
The invention relates to the technical field of impedance measurement, in particular to a load impedance measurement circuit, a load impedance measurement system and electronic equipment.
Background
In recent years, as consumer electronic products (e.g., electronic cigarettes) are used more and more widely in life, users have made higher and higher demands on the product use experience. In practical applications, a load (e.g., a heating wire of an electronic cigarette) is usually configured on a consumer electronic product, so in product design, the impedance detection accuracy of the load is very important for the operating power control of the product, and the operating power ultimately affects the product use experience of a user.
The current common measurement method on the market is to collect the current and voltage of the load and finally convert the current and voltage into the impedance of the load. However, the method needs more measured data, has larger measurement error and complicated external circuit, and causes the problems of high measurement cost and complicated calculation.
Disclosure of Invention
Aiming at the defects of the related technology, the invention provides a load impedance measuring circuit, a load impedance measuring system and electronic equipment, and aims to solve the problems that the current and voltage are required to be collected for conversion in the current load impedance measurement, the measurement process is complex and the cost is high.
In order to solve the technical problems, the invention adopts the following technical scheme:
in a first aspect, a load impedance measurement circuit is provided, which includes a main control circuit and a measurement circuit;
the measuring circuit is used for connecting an external load;
the output end of the main control circuit is used for being connected with the measuring circuit and the load respectively and supplying power to the measuring circuit and the load;
the measuring end of the main control circuit is respectively connected with the two ends of the measuring circuit and is used for acquiring signals required by measuring the load impedance;
the main control circuit is used for determining the impedance of the load according to the acquired signal.
The output end of the main control circuit comprises a general input-output end and a grounding end;
the measuring circuit is used for being connected with the load in series between the general input and output end and the grounding end; the general input and output end is used for supplying power to the measuring circuit and the load.
The main control circuit is used for determining a ratio between the impedance of the load and the resistance value of the measuring circuit according to the signal, and determining the impedance of the load according to the ratio and the resistance value of the measuring circuit.
The master control circuit comprises an analog-to-digital converter, the measuring end comprises a reference measuring end and a load measuring end, and the reference measuring end and the load measuring end are respectively connected to the analog-to-digital converter; (ii) a
The reference measuring end is connected with a first end of the measuring circuit, and the load measuring end is used for being connected with a second end of the measuring circuit and a connecting node of the load;
the analog-to-digital converter acquires a first signal of the measuring circuit through the reference measuring end;
the analog-to-digital converter is further configured to obtain a second signal of the load through the load measuring terminal, and perform analog-to-digital conversion on the second signal by using the first signal as a reference to obtain a digital code value, where the digital code value corresponds to the ratio.
Wherein the measurement circuit comprises a sampling resistor.
Wherein the master control circuit calculates the impedance of the load by the following formula:
wherein R isLoad(s)For the impedance of the load, ADC is a digital code value measured by the analog-to-digital converter, n is the digit of the analog-to-digital converter, RSampling resistorIs the impedance of the sampling resistor.
The master control circuit comprises a power supply module, and the power supply module is connected with the universal input and output end and used for supplying power to the measuring circuit and the load through the universal input and output end.
In a second aspect, there is provided a load impedance measurement system comprising a load and a load impedance measurement circuit as described above in the first aspect.
In a third aspect, an electronic device is provided, which comprises the load impedance measurement system as described in the second aspect above.
Wherein, the electronic equipment is the electron cigarette.
The invention has the beneficial effects that:
the invention provides a load impedance measuring circuit, a system and electronic equipment, wherein the measuring circuit is used for connecting an external load, the output end of a main control circuit is respectively connected with the measuring circuit and the load and supplies power to the measuring circuit and the load, and the measuring end of the main control circuit is respectively connected with the two ends of the measuring circuit and is used for acquiring signals required by measuring the load impedance and determining the impedance of the load according to the acquired signals. The load impedance can be calculated by measuring one path of signal without collecting the current and voltage of the load, the measurement error is small, the circuit is simple, and the measurement cost is reduced.
Drawings
The detailed structure of the invention is described in detail below with reference to the accompanying drawings
Fig. 1 is a schematic circuit diagram of a heating wire impedance measuring circuit provided in the related art;
fig. 2 is a schematic structural diagram of a load impedance measurement circuit connected to a load according to a first embodiment of the present invention;
fig. 3 is a schematic structural diagram of a load impedance measurement circuit connected to a load according to a second embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a heating wire impedance measuring circuit according to a third embodiment of the present invention.
Detailed Description
In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
Referring to fig. 1, fig. 1 is a schematic circuit diagram of an impedance measuring circuit of a related art when a load is a heating wire. In the heating wire impedance measurement scheme provided by the related art, the switching tube Q1 is controlled to be opened through a General Purpose Input/Output (GPIO) and simultaneously an Analog-to-Digital Converter (ADC) 1 and an ADC are opened2, measuring ADC values at two ends of the sampling resistor through channels, and calculating the difference value between the ADC1 and the ADC2 to obtain the voltage value U at two ends of the sampling resistorSampling resistorDue to the resistance R of the sampling resistorSampling resistorIs known, by calculating the formula I ═ USampling resistor/RSampling resistorAnd obtaining the current value I flowing through the heating wire. In addition, the voltage value U of the heating wire can be obtained through the ADC value of the ADC2 channelHeating wireThen by calculating the formula RHeating wire＝UHeating wireAnd I, obtaining the impedance of the heating wire.
However, in the implementation of the above solution, on one hand, the peripheral MOS switch Q1 and the resistor R4 need to be added, the circuit is complex, and the manufacturing cost is high; on the other hand, in practical application, measurement errors may be generated in both channels of the ADC1 and the ADC2, resulting in lower accuracy of the final impedance measurement result; in addition, the intermediate conversion calculation of the scheme is complex, the current of the heating wire needs to be calculated firstly, then the impedance is calculated through current conversion, and the calculation complexity is high.
Based on this, in order to solve the above-mentioned drawbacks of the related art, the present embodiment provides a load impedance measurement circuit. Referring to fig. 2, fig. 2 is a schematic structural diagram of a load impedance measurement circuit and a load according to a first embodiment of the present invention. As shown in fig. 2, the load impedance measuring circuit includes: the measuring circuit comprises a main control circuit 10 and a measuring circuit 20, wherein an output end 11 of the main control circuit 10 comprises a general input/output end 111 and a grounding end 112, the general input/output end 111 is connected with the measuring circuit 20, and the grounding end 112 is used for being connected with a load 30; when the load 30 is connected to the load impedance measuring circuit, the general input/output terminal 111, the measuring circuit 20, the load 30, and the ground terminal 112 are electrically connected in sequence to form a loop. The general input/output end 111 is used for supplying power to the measurement circuit 20 and the load 30, that is, the main control circuit 10 can directly output voltage to the measurement circuit 20 and the load 30 through the general input/output end 111 and generate current through the measurement circuit 20 and the load 30, and the current finally flows into the ground end 112 to form a complete loop;
the measuring circuit 20 is used for connecting an external load 30, the measuring circuit 20 and the load 30 are connected in series between the general input and output end 111 and the ground end 112, and the general input and output end 111 is used for supplying power to the measuring circuit 20 and the load 30; the output end 11 of the main control circuit 10 is used for being connected with the measuring circuit 20 and the load 30 respectively and supplying power to the measuring circuit 20 and the load 30; the measuring end 12 of the main control circuit 10 is respectively connected with two ends of the measuring circuit 20, and is used for acquiring signals required by measuring the impedance of the load 30; the main control circuit 10 is further configured to determine an impedance of the load according to the acquired signal.
In some embodiments, the output terminal 11 of the main control circuit 10 is connected to the measurement circuit 20 and the external load 30, respectively, and the measurement circuit 20 is also connected to the external load 30, so that the output terminal of the main control circuit 10, the measurement circuit 20 and the load 30 form a current loop, the measurement circuit 20 and the connected load 30 are powered through the output terminal of the main control circuit 10, and current is input to the measurement circuit 20 and the external load 30.
In some embodiments, the main control circuit 10 may include an MCU (micro controller Unit), and the output voltage of the MCU may be used to supply power to the measurement circuit 20 and the load 30, so that current flows through the measurement circuit 20 and the load 30.
According to the load impedance measuring circuit provided by the invention, the output end 11 of the main control circuit 10 supplies power to the measuring circuit 20 and the load 30, and the main control circuit 10 obtains a signal required for measuring the impedance of the load 30 through the measuring end 12 of the main control circuit and determines the impedance of the load according to the signal. The embodiment of the invention can calculate the impedance of the load 30 only by measuring one path of signal without respectively collecting the current and the voltage of the load 30, has small measurement error and simple circuit design, and reduces the measurement cost.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a load impedance measuring circuit and a load according to a second embodiment of the present invention.
In some embodiments, the output 11 of the master control circuit 10 includes a general input/output 111 and a ground 112. The general input/output end 111 is connected with the measuring circuit 20, and the grounding end 112 is used for being connected with the load 30; when the load 30 is connected to the load impedance measuring circuit, the general input/output terminal 111, the measuring circuit 20, the load 30, and the ground terminal 112 are electrically connected in sequence to form a loop. The general input/output terminal 111 is used to supply power to the measurement circuit 20 and the load 30, that is, the main control circuit 10 can directly output voltage to the measurement circuit 20 and the load 30 through the general input/output terminal 111 and generate current through the measurement circuit 20 and the load 30, and the current finally flows into the ground terminal 112 to form a complete loop.
In some embodiments, the main control circuit 10 is configured to determine a ratio between the impedance of the load and the resistance value of the measurement circuit according to the signal, and determine the impedance of the load according to the ratio and the resistance value of the measurement circuit.
In some embodiments, the master control circuit 10 includes an analog-to-digital converter 14, and the analog-to-digital converter 14 is connected to the measurement terminal 12 of the master control circuit 10 for obtaining a signal required for measuring the impedance of the load 30 through the measurement terminal 12. The master control circuit 10 may determine the impedance of the accessed load 30 based on the signal.
In some embodiments, the measurement terminal 12 includes a reference measurement terminal 121 and a load measurement terminal 122, the reference measurement terminal 121 is connected to a first terminal of the measurement circuit 20, and the load measurement terminal 122 is configured to be connected to a connection node between a second terminal of the measurement circuit 20 and the load 30. The analog-to-digital converter 14 obtains signals required for measuring the impedance of the load 30 through the reference measuring terminal 121 and the load measuring terminal 122, respectively.
In one embodiment, the analog-to-digital converter 14 obtains a first signal of the measuring circuit 20 through the reference measuring terminal 121, and obtains a second signal of the load 30 through the load measuring terminal 122, and performs analog-to-digital conversion on the second signal by using the first signal as a reference to obtain a digital code value, where the digital code value corresponds to a ratio between the resistance value of the load 30 and the resistance value of the measuring circuit 20. Specifically, in order to reduce the measurement error, the first terminal of the measurement circuit 20 connected to the reference measurement terminal 121 is the terminal of the measurement circuit 20 with the higher voltage, the first signal obtained by the reference measurement terminal 121 is the voltage of the first terminal, and the analog-to-digital converter 14 samples the voltage and uses the voltage as the reference voltage of the analog-to-digital conversion. Similarly, after the load 30 is connected, the load measuring terminal 122 is connected to the connection node between the measuring circuit 20 and the load 30, the second signal obtained by the load measuring terminal 122 is the voltage of the connection node between the measuring circuit 20 and the load 30, when the other end (the end not connected to the measuring circuit 20) of the load 30 is grounded, the voltage of the connection node is the voltage of the load 30 to the ground, the analog-to-digital converter 14 performs analog-to-digital conversion on the voltage of the load 30 to the ground by using the voltage of the first end of the measuring circuit 20 as a reference voltage, so as to obtain a digital code value corresponding to the ratio of the resistance value of the load to the resistance value of the measuring circuit, and the main control circuit 10 determines the impedance of the connected load 30 based on the second signal and the first signal, that is, i.e., determines the impedance of the load 30 based on the digital code value.
In addition, in the load impedance measuring circuit, the measuring circuit 20 and the load 30 connected to the load impedance measuring circuit are both supplied with power by the general input/output end 111, and current is input to the measuring circuit 20 and the load 30, so that the sources of the first signal and the second signal respectively collected by the reference measuring end 121 and the load measuring end 122 are the same and both come from the same general input/output end 111, and therefore, the influence of noise signals can be effectively suppressed.
In some embodiments, the measurement circuit 20 may include a sampling resistor, which may be comprised of one or more resistor connections. The sampling resistor is connected in series with the load 30.
In some embodiments, the master control circuit 10 is configured to determine the impedance of the load 30 from the acquired signals, i.e., the master control circuit 10 determines the impedance of the load 30 from the first signal and the second signal as reference measurements. Specifically, the main control circuit 10 calculates the impedance of the load 30 by the following formula:
wherein R isLoad(s)The ADC is a digital code value measured by the ADC 14, n is the number of bits of the ADC 14, and R is a known value of the impedance of the load 30Sampling resistorIs the impedance of the sampling resistor.
Since the impedance of the sampling resistor is known, a first signal of the measuring circuit 20 can be obtained via the reference measuring terminal 121 of the analog-to-digital converter 14, and a second signal of the load 30 can be obtained via the load measuring terminal 122, and the first signal and the second signal can be obtained via the reference measuring terminal 121 and the load measuring terminal 122, respectivelyThe first signal is used as a reference to perform analog-to-digital conversion on the second signal to obtain a digital code value, the digital code value corresponds to a ratio of the resistance value of the load 30 to the resistance value of the measuring circuit 20, and finally R can be obtained through calculation by a proportional methodLoad(s). The load impedance calculation process only involves proportion calculation, voltage and current calculation is not needed, and the calculation amount and the measurement error during impedance calculation are effectively reduced.
The number of bits of the analog-to-digital converter 14 may be 12 bits, as one embodiment.
In some embodiments, the general purpose input/output terminal 111 and the ground terminal 112 may be connected to the power supply module 13, respectively, so that the general purpose input/output terminal 111 supplies power to the measurement circuit 20 and the load 30.
As an embodiment, the main control circuit 10 may include a power supply module 13, and the power supply module 13 inputs current to the measurement circuit 20 and the load 30 through the universal input/output end 111.
As another embodiment, the power supply module 13 may not be located in the main control circuit 10, and the main control circuit 10 is directly electrically connected to the power supply module 13 to input the current to the measurement circuit 20 and the load 30 through the universal input/output end 111.
Referring to fig. 4, fig. 4 is a schematic circuit diagram of a heating wire impedance measuring circuit according to a third embodiment of the present invention. As an example, the measurement of the load impedance will be specifically described by taking the case where the load 30 is a heating wire and the number of bits of the analog-to-digital converter 14 is 12 bits.
After the heating wire is connected to the load impedance measuring circuit, the load impedance measuring circuit directly uses the general input and output end, namely GPIO, to output high level to the sampling resistor and the heating wire so as to supply power to the sampling resistor and the heating wire. Wherein a voltage signal is input to a reference measurement end of the main control circuit, i.e., an ADC-Vref end in fig. 4, at a point close to the sampling resistor, and the voltage signal is taken as a reference measurement value, and the voltage of the heating wire is collected to be higher through a load measurement end of the main control circuit, i.e., an ADC end in fig. 4, then based on a proportional method calculation formula: ADC/212＝RHeating wire/RSampling resistorThe resistance R of the heating wire can be obtainedHeating wire＝ADC*RSampling electricityResistance device/212It will be appreciated that the resistance R of the sampling resistorSampling resistorIs a known value.
The invention provides a load impedance measuring circuit, which has simpler peripheral design and low manufacturing cost; the signal acquisition objects of the reference measuring end and the load measuring end are respectively supplied with power by the unified universal input and output end, so that the influence of noise signals can be effectively inhibited; in addition, only the second signal obtained by the load measuring end is involved in the actual calculation, so that the accuracy of the impedance measuring result can be effectively improved; in addition, the load impedance can be obtained only by proportion calculation without voltage and current calculation, and the impedance measurement complexity is effectively reduced.
The embodiment of the present invention further provides a load impedance measuring system, which includes a load 30 and the load impedance measuring circuit described in the above embodiment.
In addition, the embodiment of the invention also provides electronic equipment, and the electronic equipment comprises the load impedance measuring system.
In some embodiments, the electronic device may be an electronic cigarette, a hair dryer, an electric blanket. The electronic device of this embodiment may preferably be an electronic cigarette, and accordingly, the load impedance measuring circuit is configured to measure the impedance of the heating wire of the electronic cigarette.
The invention provides a load impedance measuring circuit, a system and electronic equipment, wherein the measuring circuit is used for connecting an external load, the output end of a main control circuit is respectively connected with the measuring circuit and the load and supplies power to the measuring circuit and the load, and the measuring end of the main control circuit is respectively connected with the two ends of the measuring circuit and is used for acquiring signals required by measuring the load impedance and determining the impedance of the load according to the acquired signals. The load impedance can be calculated by measuring one path of signal without collecting the current and voltage of the load, the measurement error is small, the circuit is simple, and the measurement cost is reduced.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A load impedance measurement circuit is characterized by comprising a main control circuit and a measurement circuit;
the measuring circuit is used for connecting an external load;
the output end of the main control circuit is used for being connected with the measuring circuit and the load respectively and supplying power to the measuring circuit and the load;
the measuring end of the main control circuit is respectively connected with the two ends of the measuring circuit and is used for acquiring signals required by measuring the load impedance;
the main control circuit is used for determining the impedance of the load according to the acquired signal.
2. The load impedance measurement circuit of claim 1, wherein the output of the master control circuit comprises a general purpose input output and a ground;
the measuring circuit is used for being connected with the load in series between the general input and output end and the grounding end; the general input and output end is used for supplying power to the measuring circuit and the load.
3. The load impedance measurement circuit of claim 2, wherein the master control circuit is configured to determine a ratio between the impedance of the load and the resistance of the measurement circuit based on the signal, and to determine the impedance of the load based on the ratio and the resistance of the measurement circuit.
4. The load impedance measurement circuit of claim 3, wherein the master control circuit comprises an analog-to-digital converter, the measurement terminals comprise a reference measurement terminal and a load measurement terminal, and the reference measurement terminal and the load measurement terminal are respectively connected to the analog-to-digital converter;
the reference measuring end is connected with a first end of the measuring circuit, and the load measuring end is used for being connected with a second end of the measuring circuit and a connecting node of the load;
the analog-to-digital converter acquires a first signal of the measuring circuit through the reference measuring end;
the analog-to-digital converter is further configured to obtain a second signal of the load through the load measuring terminal, and perform analog-to-digital conversion on the second signal by using the first signal as a reference to obtain a digital code value, where the digital code value corresponds to the ratio.
5. The load impedance measurement circuit of claim 4, wherein the measurement circuit comprises a sampling resistor.
6. The load impedance measurement circuit of claim 5, wherein the master circuit calculates the impedance of the load by the equation:
wherein R isLoad(s)For the impedance of the load, ADC is a digital code value measured by the analog-to-digital converter, n is the digit of the analog-to-digital converter, RSampling resistorIs the impedance of the sampling resistor.
7. The load impedance measurement circuit of any one of claims 1-6, wherein the master control circuit comprises a power supply module connected to the common input output terminal for supplying power to the measurement circuit and the load through the common input output terminal.
8. A load impedance measurement system, characterized in that the load impedance measurement system comprises a load and a load impedance measurement circuit according to any one of claims 1 to 7.
9. An electronic device characterized in that it comprises a load impedance measurement system according to claim 8.
10. The electronic device of claim 9, wherein the electronic device is an electronic cigarette.
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| CN202110897943.9A CN113702707A (en) | 2021-08-05 | 2021-08-05 | Load impedance measuring circuit, system and electronic equipment |
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