Detection circuit and method of voltage divider circuit parameters and electric energy metering chip

Abstract

The present application belongs to the technical field of voltage detection, and provides a detection circuit for parameters of a voltage divider circuit, including a voltage divider circuit coupled to a first signal source having a first frequency, wherein the voltage divider circuit includes a first voltage divider, a second voltage divider, and a third voltage divider connected in series, wherein a voltage measurement module is connected in parallel to the second voltage divider, and the detection circuit further includes a second signal source and a DC signal source; the DC signal source is used to provide a DC bias to the voltage measurement module, and a buffer is provided at the input end of the voltage measurement module for configuring input impedance, common mode rejection, and linearity, and the voltage measurement module is used to detect a first signal component of the second frequency on the second voltage divider, and determine whether the circuit parameters of the voltage divider circuit are abnormal according to the first signal component.

Description

Technical Field

[0001] The present application belongs to the field of voltage detection technology, and in particular, relates to a detection circuit and method for voltage divider circuit parameters and an electric energy metering chip. Background Art

[0002] The development of intelligent power metering system requires the establishment of smart grid, which can help strengthen the automation and informatization of power grid, enhance the self-protection ability of power grid, and better maintain the operation and safety of power grid. Smart power metering system requires the realization of digitalization, standardization, networking and intelligence of power metering. Its digitalization refers to the use of new technologies to realize new digital power metering devices and achieve the accuracy and reliability of basic data; its intelligence refers to the ability to store users' electricity consumption information, working information of power meters (such as whether the metering accuracy has changed), and abnormal conditions of power meters (short circuit, open circuit, power theft, etc.) on the basis of accurate power metering data. Therefore, power meters with accurate automatic fault detection are an important part of smart power metering systems.

[0003] At present, in the current voltage measurement devices with fault detection, a special detection signal is generally sent to the analog to digital converter (ADC) after passing through the sampling network. The digital output after ADC conversion enters the digital processing unit for voltage amplitude and phase processing. By observing the amplitude and phase changes of the detection signal, it is possible to know the fault of the off-chip component in the off-chip sampling network, and thus know the voltage measurement error; at the same time, this ADC is also used to perform normal voltage measurement (in the electric energy meter, this voltage measurement result is ultimately used for electric energy measurement). However, the detection signal and voltage measurement signal sent to the ADC do not contain a DC component, which affects the measurement accuracy of the measured voltage and the measurement accuracy of the fault detection signal in scenarios where a DC potential bias is required. Summary of the invention

[0004] The purpose of the present application is to provide a detection circuit, method and electric energy metering chip for voltage divider circuit parameters, aiming to solve the problem that the measurement accuracy of the measured voltage and the measurement accuracy of the fault detection signal of the existing voltage measurement circuit are not high in the scenario where a DC potential bias is required.

[0005] A first aspect of an embodiment of the present application provides a detection circuit for a voltage divider circuit parameter, comprising a voltage divider circuit coupled to a first signal source having a first frequency, the voltage divider circuit comprising a first voltage divider, a second voltage divider, and a third voltage divider connected in series, a voltage measurement module being connected in parallel to the second voltage divider, and the detection circuit further comprising:

[0006] A second signal source is inputted at a connection end of the second voltage divider and the third voltage divider, and the second signal source has a second frequency;

[0007] A buffer configured with impedance, common mode rejection and linearity as required is provided at the input end of the voltage measurement module. The voltage measurement module is used to detect the first signal component of the second frequency on the second voltage divider, and determine whether the circuit parameters of the voltage divider circuit are abnormal based on the first signal component.

[0008] A second aspect of an embodiment of the present application provides a method for detecting parameters of a voltage divider circuit, comprising:

[0009] A first signal source with a first frequency is loaded at both ends of a voltage divider circuit; wherein the voltage divider circuit comprises a first voltage divider, a second voltage divider and a third voltage divider connected in series;

[0010] A second signal source with a second frequency is connected to the first connection end of the second voltage divider, and a DC signal source for providing a DC bias is connected to the first connection end or the second connection end of the second voltage divider;

[0011] A first signal component of the second frequency on the second voltage divider is detected, and whether a circuit parameter of the voltage divider circuit is abnormal is determined according to the first signal component.

[0012] A third aspect of the embodiments of the present application provides an electric energy metering chip, the electric energy metering chip comprising the above-mentioned detection circuit; the voltage divider circuit is arranged outside the electric energy metering chip.

[0013] A fourth aspect of the embodiments of the present application provides an electric energy metering chip, including a voltage divider circuit, and the electric energy metering chip also includes the above-mentioned detection circuit.

[0014] The voltage measurement module of the detection circuit of the above-mentioned voltage divider circuit parameters has a fault detection function. On this basis, a DC signal source is added. The current of the DC signal source flows through the voltage divider resistor string to provide a DC bias for the voltage measurement circuit with a fault, thereby meeting the scenario where the measuring device requires a DC potential bias, thereby improving the measurement accuracy of the voltage measurement and the measurement accuracy of the fault detection signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a module of a voltage divider circuit parameter detection circuit provided in the first embodiment of the present application;

[0016] Figure 2 A schematic diagram of a module of a voltage divider circuit parameter detection circuit provided in the second embodiment of the present application;

[0017] Figure 3 for Figure 1 or Figure 2 The schematic diagram of the principle of the first embodiment of the voltage measurement module in the detection circuit is shown;

[0018] Figure 4 for Figure 1 or Figure 2 A schematic diagram showing a second embodiment of a voltage measurement module in a detection circuit;

[0019] Figure 5 for Figure 1 or Figure 2 A schematic diagram showing a third embodiment of a voltage measurement module in a detection circuit;

[0020] Figure 6 for Figure 5 The waveforms of the measurement signal and the detection signal in the detection circuit shown;

[0021] Figure 7 A schematic diagram of a principle of a detection circuit for a voltage divider circuit parameter provided in a third embodiment of the present application;

[0022] Figure 8 A schematic diagram of the principle of a detection circuit for voltage divider circuit parameters provided in the fourth embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] See also Figure 1 and Figure 2 The detection circuit of the voltage divider circuit parameter provided in an embodiment of the present application includes a voltage divider circuit 20 coupled to a first signal source 10 having a first frequency, the voltage divider circuit 20 includes a first voltage divider 21, a second voltage divider 22 and a third voltage divider 23 connected in series, a voltage measurement module 30 is connected in parallel to the second voltage divider 22, the detection circuit also includes a second signal source 40 and a DC signal source 50, the second signal source 40 is input at the connection end of the second voltage divider 303 and the third voltage divider, and the second signal source 40 has a second frequency; the DC signal source 50 is connected at the first connection end of the second voltage divider 22 (see Figure 1 , that is, the connection end of the first voltage divider 21 and the second voltage divider 22) or the second connection end (see Figure 2, i.e., the connection end of the second voltage divider 22 and the third voltage divider 23), the DC signal source 50 is used to provide a DC bias to the voltage measurement module 30, the voltage measurement module 30 is used to detect the first signal component of the second frequency on the second voltage divider 22, and determine whether the circuit parameters of the voltage divider circuit 20 are abnormal according to the first signal component. At the same time, it can be determined whether the circuit parameters of the second signal source 40 (the feedback resistor used in the signal source generation circuit) are abnormal.

[0025] It is understandable that the second signal source 40 can also be connected through the first switch (not shown), and the voltage measurement module 30 detects the first signal component when only the first switch is connected. The second signal source 40 is an AC current source, and the DC signal source 50 is a DC current source. In addition, the measured voltage The frequency of the second signal source 40 is different from the frequency of the second signal source 40, and the second frequency is a non-integer multiple of the first frequency. When the frequency is 50Hz, the frequency of the second signal source 40 can be selected as 432Hz. The second signal source 40 is mainly a current source generated by a combination of a reference voltage source, an operational amplifier, a current mirror tube and a feedback resistor. The internal circuit of the actual current source can control the output waveform of this current source to be an AC signal through a switch. The first voltage divider 21, the second voltage divider 22 and the third voltage divider 23 are all circuits composed of at least one of a resistor, an inductor and a capacitor, and their resistance values ​​are respectively , , .

[0026] See also Figure 1 and Figure 2 The voltage measurement module 30 includes an analog-to-digital conversion unit (ADC) 31 and a digital signal processing unit (device) 32. Specifically, the DC voltage of the DC signal source 50 After flowing through the first voltage divider 21 , the second voltage divider 22 and the third voltage divider 23 , a DC level is generated at the two input terminals P / N of the ADC 31 , providing a DC bias for the ADC 31 .

[0027] The DC level generated by the input terminal P / N of ADC 31 / They are as follows:

[0028]

[0029]

[0030] In voltage measurement, the voltage to be measured is generally attenuated to within the safe range of the ADC input voltage through a sampling network (voltage divider circuit 20). The resistance value of the commonly used first voltage divider 21 is is 1M ohms, and the resistance of the second voltage divider 22 and the third voltage divider 23 is / is 1K ohms, so the DC difference of P / N at the input terminal of ADC 31 is:

[0031]

[0032] therefore / The DC voltage values ​​of the two are close, and thus a suitable DC bias can be provided to the ADC 31 .

[0033] As for the DC difference existing at the input terminal P / N of ADC 31, since the digital signal processing unit 31 will perform a high-pass filter in the DC part to filter out the DC component, the DC difference existing at the input terminal P / N of ADC 31 will not affect the measurement accuracy of the fault detection circuit and the measurement accuracy of the voltage measurement circuit. At the same time, it can meet the scenario where the measuring device requires a DC potential bias, thereby improving the measurement accuracy of the voltage measurement and the measurement accuracy of the fault detection signal.

[0034] See also Figure 3 In another embodiment, the voltage measurement module 30 includes a buffer 33, an analog-to-digital conversion unit 31, and a digital signal processing unit 32. The buffer 33 is used to configure the input impedance, common mode rejection, and linearity. The buffer 33 voltage measurement module 30 needs to detect the second signal component (voltage measurement signal) of the first frequency on the second voltage divider 22 while measuring the fault detection signal (first signal component), and also correct the circuit parameters of the voltage divider circuit 20 according to the first signal component and the second signal component, and perform normal voltage measurement according to the second signal component and the circuit parameters of the corrected voltage divider circuit 20. As an embodiment, the internal resistance R_in of the buffer 33 is above 100M ohms, such as between 200M~300Mohms. The voltage measurement module 30, with a high input impedance / high common mode rejection / high linearity buffer 33, can eliminate the phenomenon that the detection signal changes dramatically with the change of the internal resistance of the detection circuit, and can suppress the common mode part of the detection signal, and meet the linearity requirements of the detection circuit. That is, the measurement accuracy of the detection signal is guaranteed, and the linearity requirement when measuring voltage can be met.

[0035] Combination Figure 2 and Figure 3 , assuming that the frequency of the second signal source 40 is , assuming that the voltage signal to be measured is is an AC signal with a frequency of ,and , the input impedance of buffer 33 is defined as .

[0036] The voltage signal generated by the second signal source 40 at the input end of the buffer 33 through the voltage divider circuit 20 is defined as .

[0037] Separately calculate the differential voltage signal generated by the second signal source 40 through the voltage divider circuit 20 :

[0038]

[0039]

[0040] In voltage measurement, the voltage to be measured is generally attenuated to within the safe range of the input voltage of ADC 31 through a sampling network (voltage divider circuit 20). The resistance value of the commonly used first voltage divider 21 is is 1M ohms, and the resistance of the second voltage divider 22 and the third voltage divider 23 is , is 1K ohms. If the snubber internal resistance When the internal resistance of the buffer varies between 200M~300M ohms (the worst range of internal resistance variation of the buffer), the differential voltage part of the detection signal The change is about 0.1%, so the measurement accuracy of the detection signal is basically not affected by the change of the buffer internal resistance.

[0041] Separately calculate the common mode voltage signal generated by the second signal source 40 through the voltage divider circuit 20 :

[0042]

[0043]

[0044] According to the commonly used internal resistance of the first voltage divider 21, the second voltage divider 22, the third voltage divider 23 and the buffer 33 Value, can be obtained The common mode signal is more than 2000 times higher than the differential signal. Therefore, the buffer 33 is required to have a strong common mode suppression capability, which can eliminate the common mode value of the detection signal and ensure that the detection signal at the input end of the analog-to-digital conversion unit 31 has only the differential part, thereby reducing the common mode suppression requirements of the analog-to-digital conversion unit 31; at the same time, the buffer itself will not convert the common mode part of the detection signal into a differential signal. The above characteristics of the buffer ensure that the measurement accuracy of the detection signal is not affected by the common mode part of the detection signal.

[0045] At the same time, buffer 33 requires high linearity because the measured voltage It is a strong input signal with a large signal amplitude, which requires the linearity of the measuring device itself to be sufficient to meet the voltage being measured. measurement accuracy.

[0046] See also Figure 4 As another embodiment, the voltage measurement module 30 includes a first buffer 301 , a second buffer 302 , a measurement correction unit 303 and a voltage measurement unit 304 .

[0047] The first buffer 301 is used to configure input impedance and common mode rejection. The first buffer 301 is connected in parallel with the second voltage divider. The measurement correction unit 303 is connected to the first buffer 301. It can be understood that the measurement correction unit 303 includes an analog-to-digital converter and a digital signal processor. The measurement correction unit 303 is used to detect the first signal component of the second frequency on the second voltage divider, determine whether the circuit parameters of the voltage divider circuit are abnormal according to the first signal component, and correct the voltage divider circuit parameters when the circuit parameters are abnormal. The second buffer 302 is used to configure linearity. The second buffer 302 is connected in parallel with the second voltage divider. The voltage measurement unit 304 is connected to the second buffer 302. It can be understood that the voltage measurement unit 304 includes an analog-to-digital converter and a digital signal processor. The voltage measurement unit 304 is used to detect the second signal component of the first frequency on the second voltage divider. The measurement correction unit 303 corrects the voltage divider circuit parameters according to the first signal component and the second signal component. The voltage measurement unit 304 performs voltage measurement according to the second signal component and the corrected voltage divider circuit parameters.

[0048] In this embodiment, the voltage measurement signal and the fault detection signal are measured using different channels respectively, so that the normal measurement of the measurement signal is not affected while the fault detection signal is corrected; this avoids the simultaneous introduction of the detection signal and the measurement signal into the voltage measurement channel, which would affect the normal measurement of the voltage measurement device due to the correction of the detection signal.

[0049] See also Figure 5 The voltage measurement module 30 further includes an error correction switch 305, which is connected in parallel with the second voltage divider 22 and in series with the first buffer 301. The error correction switch 305 is used to flip the positive and negative of the signal of the analog-to-digital converter connected to the measurement correction unit 303. Figure 6 When the measurement correction unit 303 starts the correction function, the error correction switch 305 exchanges the positive and negative input terminals of the measurement correction unit 303 at the T1 time period and the T2 time end. The detection signal at the input terminal of the measurement correction unit 303 is named , Figure 6 The measurement correction unit 303 is shown Waveform and voltage measurement module 30 Waveform, from Figure 6 It can be seen that when the measurement correction unit 303 When the signal is corrected, the voltage measurement module 30 The signal is completely unaffected and can work normally, so it does not affect the energy measurement of the final energy meter.

[0050] See also Figure 7 and Figure 8 The detection circuit also includes a third signal source 60 with a third frequency. The third signal source 60 is input at the connection end between the first voltage divider 21 and the second voltage divider 22; the measurement correction unit 303 is also used to detect the third signal component of the third frequency on the second voltage divider 22, and determine whether the circuit parameters of the voltage divider circuit are abnormal according to the third signal component. As another embodiment, the third signal source 60 and the second signal source 40 are the same signal source, and are input at the connection end between the first voltage divider 21 and the second voltage divider 22 through another branch.

[0051] As a preferred embodiment, the measurement and correction unit 303 is specifically used to process the first signal component and the third signal component to obtain the amplitude value and phase value of the first signal component and the amplitude value and phase value of the third signal component, respectively, and determine whether the circuit parameters of the voltage divider circuit 20 are abnormal based on at least one of the amplitude value change of the first signal component, the amplitude value change of the third signal, the phase change of the first signal component, and the phase change of the third signal component.

[0052] The third signal source 60 is also an alternating current source. The second signal source 40 and the third signal source 60 may have the same or different frequencies and the same or different amplitudes.

[0053] The third signal source 60 / the second signal source 40 can also be connected through a second switch (not shown), and the measurement correction unit 303 detects the second signal component when only the second switch is connected. The third signal source 60 is an AC current source, and the measured voltage The frequency of the third signal source 60 is different from the frequency of the third signal source 60, and the third frequency is a non-integer multiple of the first frequency. When the frequency is 50 Hz, the frequency of the third signal source 60 can be selected as 432 Hz. The third signal source 60 is mainly a current source generated by a combination of a reference voltage source, an operational amplifier, a current mirror tube and a feedback resistor. The internal circuit of the actual current source can control the output waveform of this current source to be an AC signal through a switch.

[0054] As an embodiment, the internal resistance feedback resistor used in the signal source circuit of the second signal source 40 and the third signal source 60 has the same temperature coefficient as the first voltage divider 21. At the same time, the temperature coefficient of the first voltage divider 21 of the measurement channel can be offset by the temperature coefficient of the feedback resistor. In this way, the feedback resistors of the second signal source 40 and the third signal source 60 can be placed outside the chip, mainly because an AC current source with an arbitrary temperature coefficient can be obtained by selecting an off-chip resistor with an arbitrary temperature coefficient.

[0055] The second voltage divider 22, the third voltage divider 23 and the voltage measurement module 30 are on-chip devices of the integrated circuit, and the feedback resistors used in the generation circuits of the first voltage divider 21, the second signal source 40 and the third signal source 60 are off-chip devices of the integrated circuit. The main reason for placing the feedback resistors of the second signal source 40 and the third signal source 60 off-chip is that a current source with an arbitrary temperature coefficient can be obtained by selecting an off-chip resistor with an arbitrary temperature coefficient. At the same time, the temperature coefficient of the feedback resistor can be used to offset the first resistor of the measurement channel. The temperature coefficient of

[0056] The voltage divider circuit 20 is not limited to the type of impedance. For example, Z0, Z1, and Z2 in the following figure can be impedances such as resistors, capacitors, and inductors, or a combination thereof, such as impedances such as resistors and capacitors in parallel. If the sampling network includes components such as capacitors and inductors, the fault source can be located by simultaneously monitoring the amplitude and phase change of the detection signal.

[0057] An additional AC current source is introduced into the conventional voltage measurement channel, and the known information of the AC current source and certain switch timing information are used to locate whether the off-chip component has failed, so as to achieve the function of accurately locating the fault source. At the same time, through this voltage measurement device, by reasonably selecting off-chip resistors with the same temperature coefficient, the voltage measurement system can have a temperature compensation effect, which can further improve the voltage measurement accuracy and reduce the influence of temperature drift on the voltage measurement results. Among them, the applied AC current source signal can be various periodic signals, such as sine wave signals, square wave signals, triangle wave signals, etc.

[0058] The present application also provides a method for detecting parameters of a voltage divider circuit, including:

[0059] Step 1:

[0060] A first signal source with a first frequency is loaded at both ends of a voltage divider circuit; wherein the voltage divider circuit comprises a first voltage divider, a second voltage divider and a third voltage divider connected in series;

[0061] Step 2:

[0062] A second signal source with a second frequency is connected to the first connection end of the second voltage divider, and a DC signal source for providing a DC bias is connected to the first connection end or the second connection end of the second voltage divider;

[0063] Step 3:

[0064] A first signal component of the second frequency on the second voltage divider is detected, and whether a circuit parameter of the voltage divider circuit is abnormal is determined according to the first signal component.

[0065] In a further embodiment, when performing step three: when detecting the first signal component of the second frequency on the second voltage divider, a buffer is used to configure input impedance, common mode rejection and linearity of the first signal component.

[0066] In a further embodiment, the detection method further comprises:

[0067] detecting a second signal component of the first frequency on the second voltage divider;

[0068] The voltage divider circuit parameters are corrected according to the first signal component and the second signal component.

[0069] In a further embodiment, the detection method further comprises:

[0070] Connecting a third signal source having a third frequency to a second connection end of the second voltage divider;

[0071] A third signal component of the third frequency on the second voltage divider is detected, and whether a circuit parameter of the voltage divider circuit is abnormal is determined according to the third signal component.

[0072] The embodiment of the present application also provides an electric energy metering chip, which includes the aforementioned detection circuit. In the embodiment of the present application, the voltage divider circuit is arranged outside the electric energy metering chip. Specifically, the detection circuit is integrated inside the chip. At this time, the detection circuit inside the chip is not affected by the external environment. Further, the switch state of the first switch and the second switch can be pre-set in the voltage measurement module to automatically switch the switch state after startup.

[0073] The embodiment of the present application further proposes another electric energy metering chip, which includes a voltage divider circuit and the detection circuit as described above.

[0074] The voltage measurement module for detecting the parameters of the above-mentioned voltage divider circuit has a fault detection function. On this basis, a DC signal source is added. The current of the DC signal source flows through the voltage divider resistor string to provide a DC bias to the voltage measurement module with a fault, thereby meeting the scenario where the measuring device requires a DC potential bias, thereby improving the measurement accuracy of the voltage measurement and the measurement accuracy of the fault detection signal.

[0075] In addition, a buffer is added on the input side. The buffer can be set to have a high input impedance characteristic, which can eliminate the influence of the limited internal resistance of the ADC on the accuracy of the fault detection signal; the buffer can also be set to have a high common-mode suppression characteristic, which can suppress the common-mode part of the detection signal, ensuring that the fault detection signal at the output of the high common-mode buffer (the input of the ADC) no longer has a high common-mode signal, thereby reducing the common-mode suppression pressure of the ADC and improving the measurement accuracy of the fault detection signal; at the same time, the buffer can be set to have a high linearity characteristic, which can ensure the linearity requirement of the voltage measurement device when measuring a voltage signal with a strong amplitude.

[0076] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A detection circuit for a voltage divider circuit parameter, comprising a voltage divider circuit coupled to a first signal source having a first frequency, the voltage divider circuit comprising a first voltage divider, a second voltage divider and a third voltage divider connected in series, the second voltage divider being connected in parallel with a voltage measurement module, characterized in that: The detection circuit also includes: Inputting a second signal source having a second frequency to the connection end of the second voltage divider and the third voltage divider; A DC signal source connected to the first connection end or the second connection end of the second voltage divider, wherein the DC signal source is used to provide a DC bias to the voltage measurement module; The voltage measurement module is used to detect the first signal component of the second frequency on the second voltage divider, and determine whether the circuit parameters of the voltage divider circuit are abnormal according to the first signal component; The voltage measurement module includes a first buffer, a second buffer, a voltage measurement unit and a measurement correction unit, wherein: The first buffer is used to configure input impedance and common mode rejection, the first buffer is connected in parallel with the second voltage divider, and the measurement correction unit is connected to the first buffer; the measurement correction unit is used to detect a first signal component of the second frequency on the second voltage divider, determine whether a circuit parameter of the voltage divider circuit is abnormal according to the first signal component, and correct the voltage divider circuit parameter when the circuit parameter is abnormal; The second buffer is used to configure linearity, the second buffer is connected in parallel with the second voltage divider, and the voltage measuring unit is connected with the second buffer; the voltage measuring unit is used to detect the second signal component of the first frequency on the second voltage divider, and perform voltage measurement according to the second signal component and the corrected voltage divider circuit parameters; The detection circuit also includes: A third signal source having a third frequency inputted at a connection end between the first voltage divider and the second voltage divider; The voltage measurement module is further used to detect the third signal component of the third frequency on the second voltage divider, and determine whether the circuit parameters of the voltage divider circuit are abnormal according to the third signal component; The voltage measurement module is specifically used to process the first signal component and the third signal component to obtain the amplitude value and phase value of the first signal component and the amplitude value and phase value of the third signal component respectively, and determine whether the circuit parameters of the voltage divider circuit are abnormal according to at least one of the amplitude value change of the first signal component, the amplitude value change of the third signal, the phase change of the first signal component, and the phase change of the third signal component; The voltage measurement module further includes an error correction switch, the error correction switch is connected in parallel with the second voltage divider, the error correction switch is connected in series with the first buffer, and the error correction switch is used to flip the positive and negative of the signal connected to the measurement correction unit; The voltage measurement module input terminal is provided with a buffer for configuring input impedance, common mode rejection and linearity.

2. The detection circuit according to claim 1, characterized in that: The second signal source and the third signal source are AC current sources, and the DC signal source is a branch current source; the second frequency and the third frequency are the same or different, and are both non-integer multiples of the first frequency.

3. The detection circuit according to claim 1, characterized in that: The second voltage divider, the third voltage divider and the voltage measurement module are on-chip devices of the integrated circuit, and the first voltage divider and the feedback resistor used in the second signal source generation circuit are off-chip devices of the integrated circuit.

4. A method for detecting parameters of a voltage divider circuit, characterized in that: include: A first signal source with a first frequency is loaded at both ends of a voltage divider circuit; wherein the voltage divider circuit comprises a first voltage divider, a second voltage divider and a third voltage divider connected in series; A second signal source with a second frequency is connected to the first connection end of the second voltage divider, and a DC signal source for providing a DC bias is connected to the first connection end or the second connection end of the second voltage divider; Using a voltage measurement module to detect a first signal component of the second frequency on the second voltage divider, and determining whether a circuit parameter of the voltage divider circuit is abnormal according to the first signal component; Connecting a third signal source having a third frequency to a second connection end of the second voltage divider; detecting a third signal component of the third frequency on the second voltage divider, and determining whether a circuit parameter of the voltage divider circuit is abnormal according to the third signal component; The voltage measurement module includes a first buffer, a second buffer, a voltage measurement unit and a measurement correction unit, wherein: The first buffer is used to configure input impedance and common mode rejection, the first buffer is connected in parallel with the second voltage divider, and the measurement correction unit is connected to the first buffer; the measurement correction unit is used to detect a first signal component of the second frequency on the second voltage divider, determine whether a circuit parameter of the voltage divider circuit is abnormal according to the first signal component, and correct the voltage divider circuit parameter when the circuit parameter is abnormal; The second buffer is used to configure linearity, the second buffer is connected in parallel with the second voltage divider, and the voltage measuring unit is connected with the second buffer; the voltage measuring unit is used to detect the second signal component of the first frequency on the second voltage divider, and perform voltage measurement according to the second signal component and the corrected voltage divider circuit parameters; The voltage measurement module further includes an error correction switch, which is connected in parallel with the second voltage divider and in series with the first buffer, and is used to flip the positive and negative of a signal connected to the measurement correction unit.

5. The detection method according to claim 4, characterized in that: When detecting the first signal component of the second frequency on the second voltage divider, a buffer is used to configure input impedance, common mode rejection, and linearity of the first signal component.

6. An electric energy metering chip, characterized in that: The electric energy metering chip comprises the detection circuit according to any one of claims 1 to 3; the voltage divider circuit is arranged outside the electric energy metering chip.

7. An electric energy metering chip, comprising a voltage divider circuit, characterized in that: The electric energy metering chip further comprises a detection circuit as claimed in any one of claims 1 to 3.

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