High-precision current measurement method

Abstract

The invention relates to a high-precision current measurement method. The method comprises the following steps: pre-selecting and acquiring an expected current range of a branch where to-be-measured electric equipment is located; according to the expected current range, a corresponding parallel resistance network is selected to be connected with the to-be-measured electric equipment in series, the parallel resistance network is formed by connecting 2n resistors in parallel, and the voltage values of the two ends of each resistor in the parallel resistance network are measured respectively; monitoring the real-time temperature of a branch where the to-be-detected electric equipment is located in real time, and calculating the real-time resistance value of each resistor in the parallel resistor network according to the real-time temperature and the known resistance value of each resistor in the parallel resistor network; the current value flowing through each resistor is calculated according to the voltage values at the two ends of each resistor and the corresponding real-time resistance value, all the current values are accumulated to obtain a total current value, and the current flowing through the electric equipment to be detected can be obtained. The influence of internal impedance of an ammeter and electric equipment on current measurement in the prior art is effectively eliminated, and the precision of current measurement is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of high-precision current measurement methods, and in particular to a high-precision current measurement method, which is mainly used in Bluetooth headsets. Background Art

[0002] Bluetooth headsets are hands-free headsets that apply Bluetooth technology to them, allowing users to avoid the entanglement of annoying wires and easily communicate in a variety of ways, allowing them to operate a computer while maintaining a conversation.

[0003] In addition, the most widely used application of Bluetooth technology in daily life is in mobile phone communication devices that support Bluetooth, such as mobile phone Bluetooth headsets. Bluetooth makes driving safer.

[0004] In the circuit measurement of existing Bluetooth headsets, accurately obtaining the current flowing through the electrical device is an important parameter for evaluating its working status and performance.

[0005] Traditionally, people use ammeters directly connected in series in circuits to measure current. However, since the ammeter has a certain resistance inside, if the resistance is too large, the measured current value will have a large deviation. At the same time, the impedance inside the electrical equipment and the line impedance of the circuit will also affect the measurement results, which can easily cause a deviation between the measured value and the true value, affecting the accuracy and reliability of the measurement.

[0006] In addition, in the prior art, it is difficult to select appropriate measuring equipment according to actual conditions during circuit measurement, and thus it is difficult to achieve optimal measurement accuracy.

[0007] In summary, in the patent application of the present invention, the applicant has carefully studied a high-precision current measurement method to solve the above problems. Summary of the invention

[0008] The present invention aims to overcome the deficiencies in the prior art and mainly aims to provide a high-precision current measurement method, which effectively eliminates the influence of the internal impedance of the ammeter and the electrical equipment on the current measurement in the prior art and significantly improves the accuracy of the current measurement.

[0009] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: A high-precision current measurement method, comprising: Preselect and obtain the expected current range of the branch where the electrical equipment to be tested is located; According to the expected current range, a corresponding parallel resistor network is selected and connected in series with the electrical equipment to be tested. The parallel resistor network consists of 2 n resistors connected in parallel, n is a natural number not less than 1; Measure the voltage across each resistor in the parallel resistor network; Monitor the real-time temperature of the branch where the electrical equipment to be tested is located in real time, and calculate the real-time resistance value of each resistor in the parallel resistor network based on the real-time temperature and the known resistance value of each resistor in the parallel resistor network; The current value flowing through each resistor is calculated based on the voltage value across each resistor and its corresponding real-time resistance value, and all current values ​​are added up to obtain the total current value, thereby obtaining the current flowing through the electrical equipment to be tested.

[0010] As a preferred solution, after selecting a corresponding parallel resistor network and connecting it in series with the electrical equipment to be tested, if it is detected in real time that the current flowing through the branch where the electrical equipment to be tested is located changes, the parallel resistor network corresponding to the corresponding expected current range is dynamically switched according to the current change.

[0011] As a preferred solution, if it is detected in real time that the change value of the current flowing through the branch where the electrical equipment to be tested is located exceeds a first preset threshold, a warning signal will be issued and current detection will be stopped.

[0012] As a preferred solution, the total resistance values ​​of all parallel resistor networks are arranged according to an arithmetic progression.

[0013] As a preferred solution, the process of calculating the real-time resistance value of each resistor in the parallel resistor network includes: S1, pre-acquire the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, and the temperature coefficient of each resistor in the parallel resistor network; S2. Real-time monitoring of the real-time temperature of the branch where the electrical equipment to be tested is located, and obtaining the real-time temperature value; S3, according to the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, the temperature coefficient of each resistor in the parallel resistor network, and the real-time temperature value, the real-time resistance value calculation formula: R (T) = R0 [1 + α (T-T0)] can be used to calculate the real-time resistance value of each resistor in the parallel resistor network; Among them, R(T) represents the real-time resistance value, T represents the real-time temperature value, R(T) is the real-time resistance value at temperature T, α is the temperature coefficient; R0 represents the resistance value of the resistor under normal conditions, T0 represents the temperature value under normal conditions, that is, R0 is the resistance value at temperature T0; The temperature coefficient α is TCR (also known as the temperature coefficient of resistance). The temperature coefficient of each resistor is known or can be calculated: TCR (average) = (R2-R1) / R1(T2-T1), where R2 and R1 are the resistance values ​​at different temperatures, and T2 and T1 are the corresponding temperatures.

[0014] As a preferred solution, if it is measured that the voltage value across each resistor in the parallel resistor network changes and the change value exceeds a second preset threshold, a warning signal will be issued and the voltage measurement will be stopped.

[0015] As a preferred solution, after a corresponding parallel resistor network is selected and connected in series with the electrical device to be tested, an isolation transformer or photoelectric coupler is connected in series between the parallel resistor network and the electrical device to be tested for electrically isolating the two.

[0016] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, the present invention mainly selects a corresponding parallel resistor network according to the expected current range and connects it in series with the electrical equipment to be tested, then measures the voltage value of each resistor in the parallel resistor network, and then calculates the current value flowing through each resistor in combination with the real-time resistance value under temperature compensation, and accumulates all current values ​​to obtain the current value flowing through the electrical equipment to be tested, which effectively eliminates the influence of the ammeter and the internal impedance of the electrical equipment on the current measurement in the prior art, and significantly improves the accuracy of current measurement.

[0017] In order to more clearly illustrate the structural features and effects of the present invention, it is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a general flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, a high-precision current measurement method includes: The expected current range of the branch where the electrical equipment to be tested is located is pre-selected. In this embodiment, the expected current range is roughly divided into five parts, namely 0A to 0.2A, 0.2A to 0.5A, 0.5A to 1.0A, 1.0A to 2.0A and 2.0A to 4.0A, wherein: The resistance values ​​of the two parallel resistors of the parallel resistor network corresponding to 0A to 0.2A are 240 ohms and 480 ohms respectively; the resistance values ​​of the two parallel resistors of the parallel resistor network corresponding to 0.2A to 0.5A are 60 ohms and 120 ohms respectively; The resistance values ​​of the two parallel resistors of the parallel resistor network corresponding to 0.5A to 1.0A are 60 ohms and 30 ohms respectively; the resistance values ​​of the two parallel resistors of the parallel resistor network corresponding to 1.0A to 2.0A are 12 ohms and 24 ohms respectively; the resistance values ​​of the two parallel resistors of the parallel resistor network corresponding to 2.0A to 4.0A are 6 ohms and 12 ohms respectively.

[0021] A corresponding parallel resistor network is selected according to the expected current range and connected in series with the electrical equipment to be tested, wherein the parallel resistor network is composed of 2n resistors connected in parallel, and n is a natural number not less than 1. In this embodiment, the total resistance values ​​of all parallel resistor networks are arranged according to an arithmetic progression. For example, the total resistance values ​​of all parallel resistor networks are 5, 10, ..., 5N, wherein N is a natural number not less than 1.

[0022] After selecting a corresponding parallel resistance network to be connected in series with the electrical equipment to be tested, an isolation transformer or photoelectric coupler is connected in series between the parallel resistance network and the electrical equipment to be tested for electrically isolating the two, which is beneficial to improving measurement safety and anti-interference capability.

[0023] In this embodiment, after selecting the corresponding parallel resistor network to be connected in series with the electrical device to be tested, the current flowing through the branch where the electrical device to be tested is located needs to be detected in real time. If it is detected in real time that the current flowing through the branch where the electrical device to be tested is located changes, the parallel resistor network corresponding to the corresponding expected current range is dynamically switched according to the current change.

[0024] If it is detected in real time that the change value of the current flowing through the branch where the electrical equipment to be tested is located exceeds the first preset threshold, an early warning signal will be issued and the current detection will be stopped.

[0025] The voltage value across each resistor in the parallel resistor network is measured separately; in this embodiment, if the voltage value across each resistor in the parallel resistor network is measured to change and the change value exceeds a second preset threshold, a warning signal is issued and the voltage measurement is stopped.

[0026] Monitor the real-time temperature of the branch where the electrical equipment to be tested is located in real time, and calculate the real-time resistance value of each resistor in the parallel resistor network according to the real-time temperature and the known resistance value of each resistor in the parallel resistor network; it should be noted that the process of calculating the real-time resistance value of each resistor in the parallel resistor network includes: S1, pre-acquire the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, and the temperature coefficient of each resistor in the parallel resistor network; S2. Real-time monitoring of the real-time temperature of the branch where the electrical equipment to be tested is located, and obtaining the real-time temperature value; S3, according to the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, the temperature coefficient of each resistor in the parallel resistor network, and the real-time temperature value, the real-time resistance value calculation formula: R (T) = R0 [1 + α (T-T0)] can be used to calculate the real-time resistance value of each resistor in the parallel resistor network; Among them, R(T) represents the real-time resistance value, T represents the real-time temperature value, R(T) is the real-time resistance value at temperature T, α is the temperature coefficient; R0 represents the resistance value of the resistor under normal conditions, T0 represents the temperature value under normal conditions, that is, R0 is the resistance value at temperature T0; The temperature coefficient α is TCR (also known as the temperature coefficient of resistance). The temperature coefficient of each resistor is known or can be calculated: TCR (average) = (R2-R1) / R1(T2-T1), where R2 and R1 are the resistance values ​​at different temperatures, and T2 and T1 are the corresponding temperatures.

[0027] The current value flowing through each resistor is calculated based on the voltage value across each resistor and its corresponding real-time resistance value, and all current values ​​are added up to obtain the total current value, thereby obtaining the current flowing through the electrical equipment to be tested.

[0028] In this embodiment, a non-volatile memory is also provided, which can be used to store calibration data, configuration parameters and historical measurement records to ensure the traceability and repeatability of the measurement.

[0029] The key point of the design of the present invention is that it mainly selects a corresponding parallel resistor network in series with the electrical equipment to be tested according to the expected current range, then measures the voltage value of each resistor in the parallel resistor network, and then calculates the current value flowing through each resistor in combination with the real-time resistance value under temperature compensation, and accumulates all current values ​​to obtain the current value flowing through the electrical equipment to be tested, which effectively eliminates the influence of the ammeter and the internal impedance of the electrical equipment on the current measurement in the prior art, and significantly improves the accuracy of current measurement.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-precision current measurement method, characterized in that: include: Preselect and obtain the expected current range of the branch where the electrical equipment to be tested is located; According to the expected current range, a corresponding parallel resistor network is selected and connected in series with the electrical equipment to be tested. The parallel resistor network consists of 2 n resistors connected in parallel, n is a natural number not less than 1; Measure the voltage across each resistor in the parallel resistor network; Monitor the real-time temperature of the branch where the electrical equipment to be tested is located in real time, and calculate the real-time resistance value of each resistor in the parallel resistor network based on the real-time temperature and the known resistance value of each resistor in the parallel resistor network; The current value flowing through each resistor is calculated based on the voltage value across each resistor and its corresponding real-time resistance value, and all current values ​​are added up to obtain the total current value, thereby obtaining the current flowing through the electrical equipment to be tested.

2. The high-precision current measurement method according to claim 1, characterized in that: After selecting the corresponding parallel resistor network to be connected in series with the electrical equipment to be tested, if it is detected in real time that the current flowing through the branch where the electrical equipment to be tested is located changes, the parallel resistor network corresponding to the corresponding expected current range is dynamically switched according to the current change.

3. The high-precision current measurement method according to claim 2, characterized in that: If it is detected in real time that the change value of the current flowing through the branch where the electrical equipment to be tested is located exceeds the first preset threshold, an early warning signal will be issued and the current detection will be stopped.

4. The high-precision current measurement method according to claim 1, characterized in that: The total resistance of all parallel resistor networks is arranged in an arithmetic progression.

5. The high-precision current measurement method according to claim 1, characterized in that: The process of calculating the real-time resistance value of each resistor in the parallel resistor network includes: S1, pre-acquire the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, and the temperature coefficient of each resistor in the parallel resistor network; S2. Real-time monitoring of the real-time temperature of the branch where the electrical equipment to be tested is located, and obtaining the real-time temperature value; S3, according to the resistance value of each resistor in the parallel resistor network under normal conditions, the corresponding temperature value under the normal conditions, the temperature coefficient of each resistor in the parallel resistor network, and the real-time temperature value, the real-time resistance value calculation formula: R (T) = R0 [1 + α (T-T0)] can be used to calculate the real-time resistance value of each resistor in the parallel resistor network; Among them, R(T) represents the real-time resistance value, T represents the real-time temperature value, R(T) is the real-time resistance value at temperature T, α is the temperature coefficient; R0 represents the resistance value of the resistor under normal conditions, T0 represents the temperature value under normal conditions, that is, R0 is the resistance value at temperature T0; The temperature coefficient α is TCR (also known as the temperature coefficient of resistance). The temperature coefficient of each resistor is known or can be calculated: TCR (average) = (R2-R1) / R1(T2-T1), where R2 and R1 are the resistance values ​​at different temperatures, and T2 and T1 are the corresponding temperatures.

6. The high-precision current measurement method according to claim 1 or 3, characterized in that: If it is measured that the voltage value across each resistor in the parallel resistor network changes and the change value exceeds the second preset threshold value, an early warning signal will be issued and the voltage measurement will be stopped.

7. The high-precision current measurement method according to claim 1, characterized in that: After the corresponding parallel resistance network is selected and connected in series with the electrical equipment to be tested, an isolation transformer or a photoelectric coupler is connected in series between the parallel resistance network and the electrical equipment to be tested for electrically isolating the two.

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