Frequency conversion current sampling method based on mutual inductor and circuit breaker

Abstract

This application provides a variable frequency current sampling method and circuit breaker based on a current transformer, relating to the field of low-voltage electrical equipment technology. The method includes: obtaining the current operating frequency of the circuit containing the current transformer based on the current sampling time; amplifying the induced voltage value induced by the current transformer according to a preset amplification circuit, and outputting an amplified voltage value; determining the current transfer coefficient corresponding to the preset amplification circuit based on the current operating frequency; and calculating the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit. This method enables the construction of the current transfer coefficient corresponding to the preset amplification circuit based on the current operating frequency, and ensures that the influence of the current operating frequency of the circuit containing the current transformer on the target current value is considered in subsequent calculations. This allows for the sampling of the variable frequency current and the obtaining of accurate current sampling results.

Description

Technical Field

[0001] This application relates to the field of low-voltage electrical equipment technology, and in particular to a variable frequency current sampling method and circuit breaker based on a current transformer. Background Technology

[0002] A circuit breaker is a switching device used to automatically disconnect a circuit. When an overload, short circuit, or other fault occurs, the circuit breaker quickly disconnects the circuit to protect electrical equipment and wiring from damage. Circuit breakers are widely used in residential, commercial, and industrial power distribution systems.

[0003] In the existing technology, the main method for sampling variable frequency current in circuit breakers is the shunt sampling method. The shunt has the advantages of being unaffected by frequency changes and having good linearity.

[0004] However, shunt solutions require power isolation, have complex structural designs, produce small output signals, and temperature has a significant impact on product performance, which in turn leads to inaccurate current sampling results. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the prior art by providing a variable frequency current sampling method and circuit breaker based on a current transformer, which can sample the variable frequency current and obtain accurate current sampling results.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, the present invention provides a variable frequency current sampling method based on a current transformer, the method comprising:

[0008] Based on the current sampling time, obtain the current operating frequency of the circuit where the current transformer is located;

[0009] The induced voltage value induced by the current transformer is amplified according to the preset amplification circuit, and the amplified voltage value is output.

[0010] Based on the current operating frequency, the current transfer coefficient corresponding to the preset amplifier circuit is determined. The current transfer coefficient is used to indicate the relationship between the amplified voltage value output by the preset amplifier circuit and the target current value.

[0011] The target current value corresponding to the induced voltage value is calculated based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit.

[0012] In an optional implementation, determining the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes:

[0013] Obtain the transformer ratio parameters and the amplification factor of the preset amplifier circuit at the current operating frequency;

[0014] Based on the transformer ratio parameters at the current operating frequency and the amplification factor of the preset amplifier circuit, the current transfer coefficient corresponding to the preset amplifier circuit is determined.

[0015] In an optional implementation, obtaining the transformer ratio parameters at the current operating frequency includes:

[0016] Obtain the transformer ratio parameters at a preset frequency;

[0017] Calculate the transformer ratio parameters at the current operating frequency based on the transformer ratio parameters at the preset frequency, the preset frequency, and the current operating frequency.

[0018] In an optional implementation, the preset amplifier circuit includes: a first preset amplifier circuit and a second preset amplifier circuit, wherein the first preset amplifier circuit corresponds to a first current transfer coefficient, the second preset amplifier circuit corresponds to a second current transfer coefficient, and the first amplification factor corresponding to the first preset amplifier circuit is less than the second amplification factor corresponding to the second preset amplifier circuit.

[0019] The step of calculating the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit includes:

[0020] Based on the first preset amplifier circuit, calculate the first amplified voltage value corresponding to the induced voltage value;

[0021] Based on the second preset amplifier circuit, calculate the second amplified voltage value corresponding to the induced voltage value;

[0022] The target current value corresponding to the induced voltage value is calculated based on the first amplified voltage value and the second amplified voltage value.

[0023] In an optional implementation, calculating the target current value corresponding to the induced voltage value based on the first amplified voltage value and the second amplified voltage value includes:

[0024] Calculate the second target current value corresponding to the second amplified voltage value based on the second amplified voltage value and the second current transfer coefficient corresponding to the second preset amplified circuit;

[0025] If it is determined that the second target current value is less than the preset current threshold, then the second target current value is used as the target current value corresponding to the induced voltage value.

[0026] In an optional implementation, the method further includes:

[0027] If it is determined that the second target current value is greater than the preset current threshold, then the target current value corresponding to the induced voltage value is calculated based on the first amplified voltage value and the first current transfer coefficient corresponding to the first preset amplified circuit.

[0028] In an optional implementation, determining the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes:

[0029] The amplified voltage value within the current AC current cycle is sampled to obtain a set of sampled voltage values ​​corresponding to the current AC current cycle. The set of sampled voltage values ​​includes multiple sampled voltage values.

[0030] Based on the set of sampled voltage values ​​corresponding to the current unit AC cycle, calculate the current operating frequency of the circuit where the current transformer is located.

[0031] In an optional implementation, calculating the current operating frequency of the circuit containing the current transformer based on the set of sampled voltage values ​​corresponding to the current unit AC cycle includes:

[0032] Based on the set of sampled voltage values ​​corresponding to multiple AC cycles within a preset time period, obtain the number of zero-crossing sampling points corresponding to multiple AC cycles.

[0033] The current operating frequency of the circuit containing the current transformer is calculated based on the number of zero-crossing sampling points corresponding to multiple AC cycles.

[0034] Secondly, the present invention provides a circuit breaker, including a current transformer, a preset amplifier circuit, and a controller. The output of the current transformer is electrically connected to one end of the preset amplifier circuit, and the other end of the preset amplifier circuit is electrically connected to the controller. The controller is used to execute the frequency conversion current sampling method based on the current transformer as described in any of the foregoing embodiments.

[0035] In an optional implementation, the current transformer is either an air-core current transformer or an iron-core current transformer.

[0036] The beneficial effects of this application are:

[0037] The frequency conversion current sampling method and circuit breaker based on current transformers provided in this application include: obtaining the current operating frequency of the circuit where the current transformer is located based on the current sampling time; amplifying the induced voltage value induced by the current transformer according to a preset amplification circuit and outputting an amplified voltage value; determining the current transfer coefficient corresponding to the preset amplification circuit according to the current operating frequency, the current transfer coefficient being used to indicate the relationship between the amplified voltage value output by the preset amplification circuit and the target current value; and calculating the target current value corresponding to the induced voltage value according to the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit. This method enables the construction of the current transfer coefficient corresponding to the preset amplification circuit based on the current operating frequency, and ensures that the influence of the current operating frequency of the circuit where the current transformer is located on the target current value is considered in subsequent calculations. It can achieve sampling of frequency conversion current and obtain accurate current sampling results. Compared with the existing method of sampling using a shunt, it does not require power supply isolation, has the characteristics of simple design, and has less influence on the current transformer, which can improve the applicability of the method in this application. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A flowchart illustrating a frequency conversion current sampling method based on a current transformer, provided for an embodiment of this application;

[0040] Figure 2 A flowchart illustrating another variable frequency current sampling method based on a current transformer provided in this application embodiment;

[0041] Figure 3 A circuit diagram of an amplifier circuit provided in an embodiment of this application;

[0042] Figure 4 A flowchart illustrating another variable frequency current sampling method based on a current transformer provided in this application embodiment;

[0043] Figure 5 A flowchart illustrating another variable frequency current sampling method based on a current transformer provided in this application embodiment;

[0044] Figure 6 A flowchart illustrating another variable frequency current sampling method based on a current transformer provided in this application embodiment;

[0045] Figure 7 A flowchart illustrating another variable frequency current sampling method based on a current transformer provided in this application embodiment;

[0046] Figure 8 A schematic diagram of the functional modules of a circuit breaker provided in an embodiment of this application;

[0047] Figure 9 This is a schematic diagram of the functional modules of another circuit breaker provided in an embodiment of this application;

[0048] Figure 10 This is a schematic diagram of an electronic device structure provided in an embodiment of this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0051] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0052] In existing technologies, the main method for frequency conversion current sampling in circuit breakers is the shunt sampling method. Shunts have the advantages of being unaffected by frequency changes and having good linearity. However, the shunt scheme requires power isolation, has a complex structural design, produces a small output signal, and temperature has a significant impact on product performance, leading to inaccurate current sampling results.

[0053] In view of this, the present application provides a variable frequency current sampling method based on a current transformer. This method can sample the variable frequency current and obtain accurate current sampling results. Compared with the existing sampling method using a shunt, it does not require power supply isolation, has the characteristics of simple design, and the temperature has little impact on the current transformer.

[0054] Figure 1This is a flowchart illustrating a frequency conversion current sampling method based on a current transformer, provided in an embodiment of this application. The execution entity of this method can be a controller in a circuit breaker. This controller can be electrically connected to the secondary side of the current transformer, and the primary side of the current transformer can sense the electrical signals of the incoming or outgoing lines of the circuit breaker. Optionally, the controller can be a microcontroller unit (MCU), but is not limited thereto. The current transformer can be an air-core current transformer, an iron-core current transformer, etc., and is not limited thereto. To better understand this application, the following embodiments all use an air-core current transformer as an example for illustration.

[0055] like Figure 1 As shown, the method includes:

[0056] Step 101: Based on the current sampling time, obtain the current operating frequency of the circuit where the current transformer is located.

[0057] Optionally, the operating frequency of the circuit where the current transformer is located at the current sampling time can be determined based on zero-crossing detection algorithms, interpolation methods, etc., and is not limited here. It can be flexibly selected according to the actual application scenario.

[0058] Step 102: Amplify the induced voltage value of the current transformer according to the preset amplification circuit, and output the amplified voltage value.

[0059] In some embodiments, the preset amplifier circuit can be based on operational amplifiers, sampling resistors, etc., to amplify the induced voltage output by the current transformer so that it reaches the input range of the analog-to-digital converter (ADC) so that the ADC can sample it.

[0060] It should be noted that this application does not limit the amplification factor of the preset amplifier circuit. Depending on the actual application scenario, the amplification factor can be any value, such as 10, 20, 30, etc.

[0061] Step 103: Determine the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency. The current transfer coefficient is used to indicate the relationship between the amplified voltage value output by the preset amplifier circuit and the target current value.

[0062] Experiments have shown that when the operating frequency of the circuit containing the current transformer is constant, the induced voltage output by the current transformer is proportional to the current in the circuit. Furthermore, since the induced voltage output by the current transformer can be determined based on the amplification voltage and amplification factor of the preset amplifier circuit, the current transfer coefficient corresponding to the preset amplifier circuit can be constructed accordingly.

[0063] Optionally, the current transfer coefficient corresponding to the preset amplifier circuit can be constructed based on the relationship between the current operating frequency of the circuit where the current transformer is located and the preset frequency, and the amplification factor corresponding to the preset amplifier circuit. The constructed current transfer coefficient can indicate the relationship between the amplified voltage value output by the preset amplifier circuit and the target current value, which is not limited here.

[0064] It can be seen that since the current transfer coefficient corresponding to the preset amplifier circuit is related to the current operating frequency of the circuit where the transformer is located, the target current value corresponding to the induced voltage value can be calculated based on the current transfer coefficient corresponding to the preset amplifier circuit. This ensures that the influence of the current operating frequency of the circuit where the transformer is located on the target current value is taken into account in the subsequent calculation process. Therefore, the frequency converter current can be sampled to obtain accurate current sampling results.

[0065] Step 104: Calculate the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit.

[0066] Optionally, in specific settings, the input terminal of the preset amplifier circuit is electrically connected to the output terminal of the current transformer, and the output terminal of the preset amplifier circuit is electrically connected to the input terminal of the analog-to-digital converter. Then, during data acquisition, the current induced voltage value induced by the current current transformer at the current sampling time can be acquired through the preset amplifier circuit, thereby obtaining the current sampled voltage value.

[0067] Optionally, the controller can be equipped with an analog-to-digital converter (ADC). The amplified voltage value output from a preset amplifier circuit can be input into the ADC, which samples and outputs a digital signal. Based on this digital signal, and according to the current transfer coefficient of the preset amplifier circuit and the resolution of the ADC, the target current value corresponding to the induced voltage value can be calculated. The resolution of the ADC refers to the smallest analog voltage change that the ADC can distinguish. Specifically, during sampling, the ADC samples the amplified voltage value output from the preset amplifier circuit according to a preset sampling rate, and sequentially quantizes and encodes the sampled signal values ​​to output the digital signal corresponding to each sampling period.

[0068] It should be noted that, in the specific calculation, the target current value corresponding to the induced voltage value can be calculated by multiplying the digital signal output by the analog-to-digital converter, the current transfer coefficient corresponding to the preset amplifier circuit, and the resolution corresponding to the analog-to-digital converter.

[0069] In summary, this application provides a variable frequency current sampling method based on a current transformer. The method includes: obtaining the current operating frequency of the circuit containing the current transformer based on the current sampling time; amplifying the induced voltage value induced by the current transformer using a preset amplification circuit, and outputting an amplified voltage value; determining the current transfer coefficient corresponding to the preset amplification circuit based on the current operating frequency, the current transfer coefficient indicating the relationship between the amplified voltage value output by the preset amplification circuit and the target current value; and calculating the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit. This method enables the construction of the current transfer coefficient corresponding to the preset amplification circuit based on the current operating frequency, and ensures that the influence of the current operating frequency of the circuit containing the current transformer on the target current value is considered in subsequent calculations. This achieves accurate current sampling results for variable frequency current sampling. Compared to existing methods using shunts for sampling, this method does not require power isolation, has a simple design, and the temperature has a smaller impact on the current transformer, thus improving the applicability of this method.

[0070] Figure 2 This is a flowchart illustrating another frequency converter-based variable frequency current sampling method provided in this application embodiment. In optional implementations, such as... Figure 2 As shown, the above determination of the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes:

[0071] Step 301: Obtain the transformer ratio parameters and the amplification factor of the preset amplifier circuit at the current operating frequency.

[0072] Among them, the transformer ratio parameter is the ratio of the primary current to the secondary output voltage of the transformer.

[0073] Optionally, the preset amplifier circuit can be based on an operational amplifier, and its amplification factor can be any value, such as 10, 20, 30, etc., without limitation. The amplification factor of the preset amplifier circuit can be flexibly set according to the actual application scenario. It can be understood that the amplification factor of the preset amplifier circuit can be determined according to the setting method of the preset amplifier circuit and the values ​​of each component in the circuit.

[0074] Step 302: Determine the current transfer coefficient corresponding to the preset amplifier circuit based on the transformer ratio parameters at the current operating frequency and the amplification factor of the preset amplifier circuit.

[0075] The current transfer coefficient corresponding to the preset amplifier circuit can be determined by multiplying the transformer ratio parameter at the current operating frequency and the amplification factor of the preset amplifier circuit.

[0076] Optionally, let f be the current operating frequency of the circuit where the current transformer is located, H(f) be the amplification factor of the preset amplifier circuit at the current operating frequency, XL(f) be the transformation ratio parameter of the current transformer at the current operating frequency, and G be the current transfer coefficient corresponding to the preset amplifier circuit. Then the current transfer coefficient corresponding to the preset amplifier circuit can be expressed as: G=XL(f)×H(f).

[0077] Optionally, obtaining the transformer ratio parameters at the current operating frequency includes: obtaining the transformer ratio parameters at a preset frequency; and calculating the transformer ratio parameters at the current operating frequency based on the transformer ratio parameters at the preset frequency, the preset frequency, and the current operating frequency.

[0078] In some embodiments, the preset frequency can be 50Hz. If the transformer ratio parameter when the preset frequency is 50Hz is denoted as X0, then the transformer ratio parameter XL(f) at any frequency f can be expressed as: XL(f)=X0×f / 50.

[0079] In optional implementations, in some embodiments, in order to improve the applicability and sampling accuracy of the method of this application, a preset amplification circuit can be set including: a first preset amplification circuit and a second preset amplification circuit, wherein the first preset amplification circuit corresponds to a first current transfer coefficient, the second preset amplification circuit corresponds to a second current transfer coefficient, and the first amplification factor corresponding to the first preset amplification circuit is less than the second amplification factor corresponding to the second preset amplification circuit.

[0080] To better understand this application, an air-core current transformer is used as an example. The current in the circuit containing the air-core current transformer at time t can be expressed as: i(t) = Asin(2πft + φ), where A is the current amplitude, f is the current frequency, and φ is the current phase. The induced voltage in the air-core current transformer coil at time t can be expressed as U(t) = Mdi / dt, where M is the mutual inductance coefficient, which is a constant when the coil is fixed. It is understood that the purpose of the calculations in this application is to determine i(t).

[0081] Figure 3 This is a circuit diagram of an amplifier circuit provided in an embodiment of this application. Figure 3 As shown, the preset amplifier circuit may include: a first preset amplifier circuit 10 and a second preset amplifier circuit 20. Optionally, the output of the first preset amplifier circuit 10 may be the input of the inverting input terminal of the second preset amplifier circuit 20.

[0082] It should be noted that the first preset amplifier circuit 10 can be considered as a high-current channel, that is, amplifying the induced voltage value sensed by the current transformer to the first range range corresponding to the first analog-to-digital converter (ADC), so that the ADC matched with the first preset amplifier circuit 10 can sample a wider range of voltage values; the second preset amplifier circuit 20 can be seen as a low-current channel, used to further amplify the voltage value amplified by the first preset amplifier circuit 10 to the second range range corresponding to the second ADC matched with it, thereby improving sampling accuracy. The second range range corresponding to the second ADC (e.g., 0 to 3V) is a subset of the first range range corresponding to the first ADC (e.g., 0 to 5A). The range range corresponding to the ADC indicates the range between the minimum and maximum values ​​of the analog signal it can accurately convert.

[0083] Of course, the configuration of the first preset amplifier circuit 10 and the second preset amplifier circuit 20, as well as the relationship between them, are not limited to this.

[0084] The first preset amplifier circuit 10 may include: a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2, and a first operational amplifier U1. One end of the second resistor R2 is electrically connected to the output terminal IA of the current transformer (taking the above-mentioned air-core current transformer as an example, that is, the output terminal of the induced voltage U(t)), and the other end is electrically connected to the inverting input terminal IN- of the first operational amplifier U1, one end of the fourth resistor R4, and one end of the first capacitor C1, respectively. The other end of the fourth resistor R4 and the other end of the first capacitor C1 are electrically connected to the output terminal of the first operational amplifier U1 and one end of the fifth resistor R5, respectively. The other end of the fifth resistor R5 is electrically connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is grounded. One end of the third resistor R3 is electrically connected to the first reference voltage VREF1, and the other end is electrically connected to the non-inverting input terminal IN+ of the first operational amplifier U1.

[0085] In addition, it should be noted that the power supply terminal of the first operational amplifier U1 is connected to the preset power supply, the ground terminal of the first operational amplifier U1 is grounded, and the other end of the fifth resistor R5 is the output terminal IAL of the first preset amplifier circuit 10.

[0086] The second preset amplifier circuit 20 may include: a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3, and a second operational amplifier U2. One end of the sixth resistor is electrically connected to the inverting input terminal IN- of the second operational amplifier U2, and one end of the eighth resistor R8 is electrically connected to the second reference voltage VREF2. One end of the seventh resistor R7 is electrically connected to the second reference voltage VREF2, and the other end is electrically connected to the non-inverting input terminal IN+ of the second operational amplifier U2. The other end of the eighth resistor R8 is electrically connected to the output terminal of the second operational amplifier U2, and one end of the ninth resistor R9 is electrically connected to one end of the third capacitor C3. The other end of the third capacitor C3 is grounded.

[0087] It should be noted that the values ​​of the first reference voltage VREF1 and the second reference voltage VREF2 can be the same or different, and are not limited here. Optionally, the values ​​of the first reference voltage VREF1 and the second reference voltage VREF2 can be 3.3V, but are not limited thereto.

[0088] In addition, it should be noted that the power supply terminal of the second operational amplifier U2 is connected to the preset power supply VCC, the ground terminal of the second operational amplifier U2 is grounded, and the other end of the ninth resistor R9 is the output terminal IAH of the second preset amplifier circuit 20.

[0089] Based on the circuit diagram above, the first current transfer coefficient GH(f) corresponding to the first preset amplifier circuit can be expressed as: GH(f) = XL(f) * X1(f), where X1(f) represents the amplification factor corresponding to the first preset amplifier circuit, and X1(f) = Z 反馈 / R2, Z 反馈 This represents the feedback resistor in the first preset amplifier circuit.

[0090] in, f represents the operating frequency of the circuit containing the current transformer, i.e.

[0091]

[0092] Furthermore, Where X0 represents the transformer ratio parameter when the preset frequency is 50Hz.

[0093] Furthermore, the second current transfer coefficient GL(f) corresponding to the second preset amplifier circuit can be expressed as:

[0094] GL(f) = XL(f) * X1(f) * X2(f), where X2(f) = R8 / R 6， X2(f) represents the amplification factor corresponding to the second preset amplifier circuit.

[0095] Furthermore,

[0096] Optionally, sampling can be performed using an analog-to-digital converter (ADC). In some embodiments, the number of ADCs can be the same as the number of preset amplifier circuits. For example, the ADCs can be configured to include a first ADC and a second ADC, wherein the range of the second ADC is a subset of the range of the first ADC.

[0097] This application does not limit the specific values ​​of the first magnification factor and the second magnification factor. Optionally, the first magnification factor can be a number less than 1, such as 1 / 20 or 1 / 10, and the second magnification factor can be a number greater than 1, such as 20 or 30. Optionally, the number of bits of the first analog-to-digital converter and the second analog-to-digital converter can be the same or different, and this is not limited here. For example, the first analog-to-digital converter can have 8 bits and the second analog-to-digital converter can have 12 bits. Of course, the specific setting is not limited to this.

[0098] Figure 4 This is a flowchart illustrating another frequency converter-based variable frequency current sampling method provided in this application embodiment. In optional implementations, such as... Figure 4 As shown, the above calculation of the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit includes:

[0099] Step 401: Based on the first preset amplifier circuit, calculate the first amplified voltage value corresponding to the induced voltage value.

[0100] The first amplified voltage value is the voltage value obtained by amplifying the induced voltage induced by the current transformer using a first preset amplification circuit. The first amplified voltage value can be determined based on the first amplification factor corresponding to the first preset amplification circuit.

[0101] Step 402: Based on the second preset amplifier circuit, calculate the second amplified voltage value corresponding to the induced voltage value.

[0102] The second amplified voltage value is the voltage value obtained by amplifying the induced voltage of the current transformer using a second preset amplification circuit. The second amplified voltage value can be determined based on the second amplification factor corresponding to the second preset amplification circuit.

[0103] It should be noted that the first magnification is less than the second magnification. Of course, this application does not limit the values ​​of the first magnification and the second magnification.

[0104] Step 403: Calculate the target current value corresponding to the induced voltage value based on the first amplified voltage value and the second amplified voltage value.

[0105] After obtaining the first amplified voltage value and the second amplified voltage value, the target current value corresponding to the induced voltage value can be calculated by combining the first analog-to-digital converter corresponding to the first preset amplification circuit, the first current transfer coefficient corresponding to the first preset amplification circuit, the second analog-to-digital converter corresponding to the second preset amplification circuit, and the second current transfer coefficient corresponding to the second preset amplification circuit.

[0106] Figure 5 This is a flowchart illustrating another frequency converter-based variable frequency current sampling method provided in this application embodiment. In optional implementations, such as... Figure 5 As shown, the above calculation of the target current value corresponding to the induced voltage value based on the first amplified voltage value and the second amplified voltage value includes:

[0107] Step 501: Calculate the second target current value corresponding to the second amplified voltage value based on the second current transfer coefficient corresponding to the second preset amplified circuit.

[0108] In the specific calculation, the second amplified voltage obtained by the second preset amplifier circuit can be sampled by the second analog-to-digital converter to obtain multiple second sampled voltage values. According to the number of bits of the second analog-to-digital converter, the multiple second sampled voltage values ​​are quantized to obtain quantized values. The quantized values ​​are then encoded to obtain the corresponding binary code. The second target current value corresponding to the induced voltage value can be calculated by multiplying the binary code, the second current transfer coefficient corresponding to the second preset amplifier circuit, and the resolution corresponding to the second analog-to-digital converter.

[0109] Step 502: If it is determined that the second target current value is less than the preset current threshold, then the second target current value is used as the target current value corresponding to the induced voltage value.

[0110] The preset current threshold can be the maximum current value corresponding to the second analog-to-digital converter (ADC), which can be determined by multiplying the maximum range of the second ADC, the second current transfer coefficient of the second preset amplifier circuit, and the resolution of the second ADC. For example, if the second range of the second ADC is 0 to 3V, then the maximum current value of the second ADC can be 1000A. Of course, specific applications are not limited to this example.

[0111] It is understandable that if the second target current value is less than the preset current threshold, it means that a relatively accurate current value can be obtained through the first preset amplifier circuit and the first analog-to-digital converter. In this case, the second target current value can be used as the target current value corresponding to the induced voltage value.

[0112] In alternative implementations, such as Figure 5As shown, the above method also includes:

[0113] Step 503: If it is determined that the second target current value is greater than the preset current threshold, then calculate the target current value corresponding to the induced voltage value based on the first amplified voltage value and the first current transfer coefficient corresponding to the first preset amplified circuit.

[0114] It is understandable that if the second target current value is greater than the preset current threshold, it means that the first preset amplifier circuit and the first analog-to-digital converter cannot obtain a relatively accurate current value at this time. In this case, the accurate current value can be calculated by the first preset amplifier circuit and the first analog-to-digital converter.

[0115] Specifically, during the calculation, the first amplified voltage obtained by the first preset amplification circuit can be sampled by the first analog-to-digital converter to obtain multiple first sampled voltage values. According to the number of bits of the first analog-to-digital converter, the multiple first sampled voltage values ​​are quantized to obtain quantized values. The quantized values ​​are then encoded to obtain the corresponding binary code. The first target current value corresponding to the induced voltage value can be calculated by multiplying the binary code, the first current transfer coefficient corresponding to the first preset amplification circuit, and the resolution corresponding to the first analog-to-digital converter.

[0116] In summary, by applying the embodiments of this application, when a precise target current value cannot be calculated using the second preset amplifier circuit and the second analog-to-digital converter, a precise target current value can be calculated by using the first preset amplifier circuit and the first analog-to-digital converter, thereby improving the flexibility of the method of this application.

[0117] Figure 6 This is a flowchart illustrating another frequency converter-based variable frequency current sampling method provided in this application embodiment. In optional implementations, such as... Figure 6 As shown, in an optional implementation, determining the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes:

[0118] Step 601: Sample the amplified voltage value within the current AC cycle to obtain the sampled voltage value set corresponding to the current AC cycle. The sampled voltage value set includes multiple sampled voltage values.

[0119] Step 602: Calculate the current operating frequency of the circuit where the current transformer is located based on the set of sampled voltage values ​​corresponding to the current unit AC cycle.

[0120] Here, a unit AC cycle is also known as a one-cycle cycle. Optionally, when calculating the current operating frequency of the circuit where the current transformer is located, the amplified voltage value within the current unit AC cycle can be sampled using an analog-to-digital converter to obtain multiple sampled voltage values ​​corresponding to the current unit AC cycle. Based on these multiple sampled voltage values, a zero-crossing detection algorithm is used to record the number of zero-crossing sampling points. Furthermore, the current operating frequency of the circuit where the current transformer is located is calculated based on the number of zero-crossing sampling points. In some embodiments, the current operating frequency of the circuit where the current transformer is located can be any value between 50Hz and 60Hz, which is not limited here and may vary depending on the actual application scenario.

[0121] Optionally, the analog-to-digital converter in this application embodiment can be either the first analog-to-digital converter or the second analog-to-digital converter described above. No limitation is made here, and the appropriate converter can be flexibly selected according to the actual application scenario.

[0122] Figure 7 This is a flowchart illustrating another frequency converter-based variable frequency current sampling method provided in this application embodiment. In optional implementations, such as... Figure 7 As shown, the above calculation of the current operating frequency of the circuit containing the current transformer, based on the set of sampled voltage values ​​corresponding to the current unit AC cycle, includes:

[0123] Step 701: Based on the set of sampled voltage values ​​corresponding to multiple AC cycles within a preset time period, obtain the number of zero-crossing sampling points corresponding to multiple AC cycles.

[0124] Step 702: Calculate the current operating frequency of the circuit where the current transformer is located based on the number of zero-crossing sampling points corresponding to multiple AC cycles.

[0125] Specifically, during the calculation, a preset time period including the current time can be determined based on the current time. This preset time period can include multiple AC cycle units. Referring to the method described above, the set of sampled voltage values ​​corresponding to these multiple AC cycle units is obtained, and the number of zero-crossing sampling points corresponding to each AC cycle unit is counted accordingly.

[0126] Furthermore, based on the number of zero-crossing sampling points corresponding to each AC cycle and the sampling interval corresponding to the analog-to-digital converter, the operating frequency corresponding to each AC cycle can be calculated.

[0127] In some embodiments, to improve the accuracy of the calculation results and reduce calculation errors, the average value of the operating frequencies corresponding to the multiple AC cycles can be calculated. This average value can be used as the current operating frequency of the circuit where the current transformer is located at the current sampling time, thereby allowing the current operating frequency to be calculated in real time. It is understood that the calculated current operating frequency can be substituted into the relevant formulas mentioned above to obtain the relevant current transfer coefficients. For details, please refer to the aforementioned related content, which will not be repeated here.

[0128] Figure 8 This is a functional module diagram of a circuit breaker provided in an embodiment of this application. Optionally, as shown... Figure 8 As shown, the circuit breaker 100 includes: a current transformer 50, a preset amplifier circuit 60, and a controller 70. The output of the current transformer 50 is electrically connected to one end of the preset amplifier circuit 60, and the other end of the preset amplifier circuit 60 is electrically connected to the controller 70. The controller 70 is used to execute the frequency conversion current sampling method based on the current transformer in any of the above embodiments.

[0129] Optionally, the aforementioned current transformer can be an air-core current transformer or an iron-core current transformer. It should be noted that when using different types of current transformers, the preset amplifier circuit can be flexibly adjusted.

[0130] Based on the above description, by applying the embodiments of this application, it is possible to construct the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency, and then calculate the target current value corresponding to the induced voltage value based on this. It can be ensured that the influence of the current operating frequency of the circuit where the current transformer is located on the target current value is considered in the subsequent calculation process. It can realize the sampling of the frequency conversion current and obtain accurate current sampling results. Compared with the existing method of sampling using a shunt, it does not require power supply isolation, has the characteristics of simple design, and has less influence on the current transformer, which can improve the applicability of the method of this application.

[0131] Figure 9 This is a schematic diagram of the functional modules of another circuit breaker provided in an embodiment of this application. Figure 9 As shown, the circuit breaker 100 may also include a display unit 81, a communication unit 82, a tripping circuit 83, a power supply circuit 84, and a memory 85, which are electrically connected to the controller 70 respectively. The tripping circuit 83 is also electrically connected to the trip unit 86.

[0132] Each module has at least the following functions: the controller 70 can be used to execute the frequency conversion current sampling method based on the current transformer in any of the above embodiments, and generate a tripping control command based on the sampled target current value and send it to the tripping circuit 83; the display unit 81 is used to display the human-machine interface, through which the circuit breaker can be tripped or closed; the communication unit 82 is used for external communication, for example, it can communicate with external devices and receive tripping or closing control commands sent by external devices; the tripping circuit 83 is used to control the trip unit to disconnect according to the tripping command sent by the controller; the power supply circuit 84 can be used to provide power to the entire control system; and the memory 85 is used to store relevant data and commands in the control process.

[0133] Of course, it should be noted that the functions of each module are not limited to those described above, and can be flexibly configured according to the actual application scenario.

[0134] These modules can be one or more integrated circuits configured to implement the above methods, such as one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors, or one or more Field Programmable Gate Arrays (FPGAs). Alternatively, when a module is implemented using processing element scheduler code, the processing element can be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. Furthermore, these modules can be integrated together as a system-on-a-chip (SOC).

[0135] Figure 10 This is a schematic diagram of an electronic device structure provided in an embodiment of this application. The electronic device can be the controller described above. Figure 10 As shown, the electronic device may include a processor 210, a storage medium 220, and a bus 230. The storage medium 220 stores machine-readable instructions executable by the processor 210. When the electronic device is running, the processor 210 communicates with the storage medium 220 via the bus 230, and the processor 210 executes the machine-readable instructions to perform the steps of the above method embodiment. The specific implementation and technical effects are similar and will not be described in detail here.

[0136] Optionally, this application also provides a storage medium storing a computer program, which, when run by a processor, executes the steps of the above-described method embodiments. The specific implementation and technical effects are similar and will not be repeated here.

[0137] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0138] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0139] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in a combination of hardware and software functional units.

[0140] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0141] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes that element.

[0142] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need further definition and explanation in subsequent figures. The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A variable frequency current sampling method based on a current transformer, characterized in that, The method includes: Based on the current sampling time, obtain the current operating frequency of the circuit where the current transformer is located; The induced voltage value induced by the current transformer is amplified according to the preset amplification circuit, and the amplified voltage value is output. Based on the current operating frequency, the current transfer coefficient corresponding to the preset amplifier circuit is determined. The current transfer coefficient is used to indicate the relationship between the amplified voltage value output by the preset amplifier circuit and the target current value. The target current value corresponding to the induced voltage value is calculated based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit.

2. The method according to claim 1, characterized in that, The step of determining the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes: Obtain the transformer ratio parameters and the amplification factor of the preset amplifier circuit at the current operating frequency; Based on the transformer ratio parameters at the current operating frequency and the amplification factor of the preset amplifier circuit, the current transfer coefficient corresponding to the preset amplifier circuit is determined.

3. The method according to claim 2, characterized in that, The process of obtaining the transformer ratio parameters at the current operating frequency includes: Obtain the transformer ratio parameters at a preset frequency; Calculate the transformer ratio parameters at the current operating frequency based on the transformer ratio parameters at the preset frequency, the preset frequency, and the current operating frequency.

4. The method according to claim 2, characterized in that, The preset amplifier circuit includes: a first preset amplifier circuit and a second preset amplifier circuit, wherein the first preset amplifier circuit corresponds to a first current transfer coefficient, the second preset amplifier circuit corresponds to a second current transfer coefficient, and the first amplification factor corresponding to the first preset amplifier circuit is less than the second amplification factor corresponding to the second preset amplifier circuit. The step of calculating the target current value corresponding to the induced voltage value based on the amplified voltage value and the current transfer coefficient corresponding to the preset amplification circuit includes: Based on the first preset amplifier circuit, calculate the first amplified voltage value corresponding to the induced voltage value; Based on the second preset amplifier circuit, calculate the second amplified voltage value corresponding to the induced voltage value; The target current value corresponding to the induced voltage value is calculated based on the first amplified voltage value and the second amplified voltage value.

5. The method according to claim 4, characterized in that, The step of calculating the target current value corresponding to the induced voltage value based on the first amplified voltage value and the second amplified voltage value includes: Calculate the second target current value corresponding to the second amplified voltage value based on the second amplified voltage value and the second current transfer coefficient corresponding to the second preset amplified circuit; If it is determined that the second target current value is less than the preset current threshold, then the second target current value is used as the target current value corresponding to the induced voltage value.

6. The method according to claim 5, characterized in that, The method further includes: If it is determined that the second target current value is greater than the preset current threshold, then the target current value corresponding to the induced voltage value is calculated based on the first amplified voltage value and the first current transfer coefficient corresponding to the first preset amplified circuit.

7. The method according to any one of claims 1-6, characterized in that, The step of determining the current transfer coefficient corresponding to the preset amplifier circuit based on the current operating frequency includes: The amplified voltage value within the current AC current cycle is sampled to obtain a set of sampled voltage values ​​corresponding to the current AC current cycle. The set of sampled voltage values ​​includes multiple sampled voltage values. Based on the set of sampled voltage values ​​corresponding to the current unit AC cycle, calculate the current operating frequency of the circuit where the current transformer is located.

8. The method according to claim 7, characterized in that, The step of calculating the current operating frequency of the circuit containing the current transformer based on the set of sampled voltage values ​​corresponding to the current unit AC cycle includes: Based on the set of sampled voltage values ​​corresponding to multiple AC cycles within a preset time period, obtain the number of zero-crossing sampling points corresponding to multiple AC cycles. The current operating frequency of the circuit containing the current transformer is calculated based on the number of zero-crossing sampling points corresponding to multiple AC cycles.

9. A circuit breaker, characterized in that, The device includes a current transformer, a preset amplifier circuit, and a controller. The output of the current transformer is electrically connected to one end of the preset amplifier circuit, and the other end of the preset amplifier circuit is electrically connected to the controller. The controller is used to execute the variable frequency current sampling method based on the current transformer as described in any one of claims 1-8.

10. The circuit breaker according to claim 9, characterized in that, The current transformer is either an air-core current transformer or an iron-core current transformer.

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