A detection circuit for voltage measurement circuit parameters and electric energy metering chip

Abstract

The present application relates to the technical field of integrated circuits, and discloses a detection circuit for voltage measurement circuit parameters and an electric energy metering chip. The voltage detection circuit of the present application includes a reference signal source, a first and a second voltage divider circuit connected in parallel, and a voltage measurement module, and the reference signal source is coupled to the first voltage divider circuit, so that the reference signal source signal can be directly separated by subtracting the voltage signal without the reference signal source from the voltage signal with the reference signal source added. Then, when the frequency of the reference signal source changes, the extraction of the reference signal source signal will not be affected, and by improving the internal hardware of the chip, the subsequent processing can be simplified, and the reliability of the system is enhanced.

Description

Technical Field

[0001] The present application belongs to the technical field of integrated circuits, and in particular relates to a circuit parameter detection circuit and an electric energy metering chip. Background Art

[0002] In the power supply system, electric energy measurement usually includes the measurement of voltage, current, power, etc., among which voltage measurement is an indispensable technology in the electronic system. At present, the voltage signal in the environment is measured by the built-in ADC or external analog-to-digital converter (ADC) in the metering chip. However, when measuring AC signals, the changes in the external environment cannot be effectively recognized by the ADC, which will cause measurement errors. Therefore, it is necessary to adopt a measurement circuit and measurement method with automatic voltage calibration.

[0003] In the existing technology, such as Figure 1 A typical voltage detection device with a voltage self-calibration function is shown, and the voltage measurement device includes a first signal source, a second signal source (reference voltage source), a voltage divider circuit, an analog-to-digital conversion module, and a signal processing module. The voltage of the first signal source is divided by the first voltage divider and the second voltage divider, and then the voltage value of the first signal source is measured. On this basis, a high-frequency second signal source (reference voltage source) is superimposed in series at the bottom of the voltage divider circuit, and the final detected voltage is a mixed voltage of the first signal source and the second signal source. The detected voltage needs to be converted into a digital signal by the analog-to-digital conversion module, and finally the digital signal is decomposed by the signal processing module to obtain the signals of the first signal source and the second signal source (reference voltage source), and then processed. Since the reference voltage source is fixed, the signal processing module can detect whether the external voltage divider circuit has changed according to the reference voltage source signal decomposed from the detected voltage, and can compensate the voltage measurement module to achieve the purpose of self-calibration.

[0004] The hardware structure of this method is simple, but there is a certain technical difficulty in separating the first signal source and the reference voltage source signal in the voltage under test. In addition, in practical applications, the voltage amplitude and frequency of the reference voltage source are affected by environmental factors such as temperature, air pressure, and electromagnetic fields, and cannot remain completely unchanged. In particular, the frequency of the reference voltage source is more easily affected, thereby affecting calibration and compensation.

[0005] Therefore, how to accurately extract the voltage signal of the reference signal source when the frequency of the reference signal source changes slightly has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0006] The purpose of the present application is to provide a detection circuit for voltage measurement circuit parameters and an electric energy metering chip, which can still accurately extract the signal of the reference signal source when the frequency of the reference signal source changes slightly, thereby increasing the reliability of the entire system under the premise that the stability of the reference signal source remains unchanged.

[0007] In order to solve the above problems, the present application discloses a detection circuit for voltage measurement circuit parameters, including a first voltage divider circuit coupled to a first signal source having a first frequency, a second voltage divider circuit connected in parallel with the first voltage divider circuit, a voltage measurement module and a second signal source having a second frequency;

[0008] The first voltage divider circuit comprises first, second and third voltage dividers connected in series in sequence; the second signal source is coupled to the connection point of the second and third voltage dividers;

[0009] The second voltage divider circuit includes fourth and fifth voltage dividers connected in series;

[0010] The connection point of the first and second voltage dividers is coupled to the first input terminal of the voltage measurement module; the connection point of the fourth and fifth voltage dividers is coupled to the second input terminal of the voltage measurement module;

[0011] The voltage measurement module is used to determine whether the circuit parameters of the first voltage divider circuit have changed by detecting the voltage difference between the first and second input terminals;

[0012] The first frequency is different from the second frequency.

[0013] In a preferred example, the |impedance of the first voltage divider| / |(impedance of the second voltage divider+impedance of the third voltage divider)|=|impedance of the fourth voltage divider| / |impedance of the fifth voltage divider|.

[0014] In a preferred example, the voltage measurement module further includes an analog-to-digital conversion module and a signal processing module; the analog-to-digital conversion module is used to perform analog-to-digital conversion on the voltages detected on the first and second input terminals, respectively, to obtain a first voltage value and a second voltage value, and then calculate the difference between the first and second voltage values; the signal processing module is used to calculate the amplitude change and / or phase change of the signal component of the second frequency based on the difference to determine whether the circuit parameters of the voltage divider circuit have changed.

[0015] In a preferred example, a first switch component is provided between the second signal source and a connection point between the second and third voltage dividers.

[0016] In a preferred example, a second switch component is provided between the fifth voltage divider and the ground.

[0017] In a preferred example, the second signal source is an AC reference current source.

[0018] In a preferred example, the first to fifth voltage dividers are circuits composed of at least one of a resistor, an inductor, and a capacitor.

[0019] In a preferred example, the second frequency is not equal to any integer multiple of the first frequency.

[0020] In a preferred example, the present application also discloses an electric energy metering chip, which includes the above-mentioned detection circuit.

[0021] In a preferred example, the present application also discloses an electric energy metering chip, and other components in the above-mentioned detection circuit except the first and second voltage divider circuits are arranged inside the electric energy metering chip, and the first and second voltage divider circuits are arranged outside the electric energy metering chip.

[0022] Compared with the prior art, the technical solution of the present application is innovative in that: (1) a reference current source is added to the voltage divider circuit to detect whether the circuit parameters have changed; (2) an additional voltage divider circuit is added to directly separate the reference signal by using the voltage with the reference signal added minus the voltage without the reference signal added. When the frequency of the reference signal changes, the i ref (3) Through hardware improvements, the complexity of subsequent processing and the reliability of the system are simplified. Through these technical improvements, when the frequency of the above-mentioned reference current source changes slightly, the signal of the reference source can still be accurately extracted. Under the premise of the stability of the reference signal source remains unchanged, the reliability of the entire system is increased.

[0023] A large number of technical features are recorded in the specification of this application, which are distributed in various technical solutions. If all possible combinations of technical features of this application (i.e., technical solutions) are to be listed, the specification will be too long. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of this application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all deemed to have been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be deemed to have been recorded because it is technically infeasible, and the solution of A+B+C+E should be deemed to have been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a circuit diagram of a typical voltage detection circuit with voltage self-calibration function in the prior art.

[0025] Figure 2 A circuit block diagram of a detection circuit for a voltage measurement circuit parameter according to the first embodiment of the present application

[0026] Figure 3 A specific circuit diagram of a detection circuit for a voltage measurement circuit parameter according to the first embodiment of the present application

[0027] Among them, 1-first voltage divider circuit 2-second voltage divider circuit

[0028] 3- Voltage measurement module 4- First input terminal

[0029] 5- Second input terminal DETAILED DESCRIPTION

[0030] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0032] The first embodiment of the present application relates to a detection circuit for a voltage measurement circuit parameter, the structure of which is as follows: Figure 2 As shown, the detection circuit includes a first voltage divider circuit 1 coupled to a first signal source having a first frequency (e.g., an AC power grid), a second voltage divider circuit 2 connected in parallel with the first voltage divider circuit 1, a voltage measurement module 3, and a second signal source having a second frequency (e.g., an AC reference current source);

[0033] The first voltage divider circuit 1 comprises first, second and third voltage dividers connected in series in sequence; the second signal source is coupled to the connection point of the second and third voltage dividers;

[0034] The second voltage divider circuit 2 includes a fourth and a fifth voltage divider connected in series;

[0035] The connection point of the first and second voltage dividers is coupled to the first input terminal 4 of the voltage measurement module 3; the connection point of the fourth and fifth voltage dividers is coupled to the second input terminal 5 of the voltage measurement module 3;

[0036] The voltage measuring module 3 is used to determine whether the circuit parameters of the first voltage divider circuit 1 have changed by detecting the voltage difference between the first input terminal 4 and the second input terminal 5;

[0037] The voltage measurement module 3 further includes an analog-to-digital conversion module and a signal processing module; the analog-to-digital conversion module is used to perform analog-to-digital conversion on the voltage detected on the first input terminal 4 and the second input terminal 5, respectively, to obtain a first voltage value and a second voltage value, and then calculate the difference between the first and second voltage values; the signal processing module is used to calculate the amplitude change and / or phase change of the signal component of the second frequency according to the difference to determine whether the circuit parameters of the voltage divider circuit have changed. By reasonably setting the impedance of the first to fifth voltage dividers, the processing of the analog-to-digital conversion module can be simplified, and the signal of the second signal source can be extracted only through a subtractor.

[0038] The first frequency is different from the second frequency. In a preferred embodiment, the value of the second frequency is greater than the value of the first frequency, and the second frequency is not equal to any integer multiple of the first frequency. For example, when the frequency of the measured voltage Us is 50 Hz, the reference current signal source i ref The frequency can be selected as 233 Hz. Specifically, the second signal source introduced in this embodiment is an independent signal source that cannot be interfered by the measured voltage. Therefore, the second frequency of the second signal source cannot be the same as the first frequency of the first signal source, nor can it be an integer multiple. If the second frequency of the second signal source is the same as or an integer relationship with the first frequency of the first signal source, signal resonance or interference signals will occur between the first frequency and the second frequency, causing distortion of the measurement result.

[0039] In a preferred example, |impedance of the first voltage divider| / |(impedance of the second voltage divider+impedance of the third voltage divider)|=|impedance of the fourth voltage divider| / |impedance of the fifth voltage divider|.

[0040] In another embodiment, |impedance of the first voltage divider| / |(impedance of the second voltage divider+impedance of the third voltage divider)| may not be equal to |impedance of the fourth voltage divider| / |impedance of the fifth voltage divider|. In this case, the analog-to-digital conversion module will not be able to extract the signal of the second signal source by direct subtraction, and a multiplier needs to be added to multiply the voltage value of the second input terminal 5 by a predetermined coefficient, and then subtract it from the voltage value of the first input terminal 4 to obtain the signal of the second signal source and output it to the signal processing module.

[0041] Optionally, a first switch component is provided between the second signal source and the connection point of the second and third voltage dividers. A second switch component is provided between the fifth voltage divider and the ground. By closing and opening the two switch components, it is possible to detect whether the circuit parameters of the voltage divider circuit have changed at a selected time, rather than being in a detection state all the time. In another embodiment, the two switch components may not be provided. Specifically, the first switch component SW1 and the second switch component SW2 may be MOS tubes, and the first switch component SW1 is used to control the AC current source i refThe state of the first switch component SW1 and the second switch component SW2 is ensured by the timing of reasonable control by the switch signal generator. The first switch component SW1 and the second switch component SW2 can be disconnected during normal measurement. When it is necessary to detect whether the voltage divider circuit parameters have a fault, the first switch component SW1 and the second switch component SW2 can be closed at the same time.

[0042] The first to fifth voltage dividers can be implemented in various ways. Optionally, the first to fifth voltage dividers are all resistors. Optionally, the first to fifth voltage dividers are circuits composed of at least one of a resistor, an inductor, and a capacitor; specifically, the voltage divider circuit is not limited to the type of impedance, and can also be any number of resistors, capacitors, inductors and other impedances, or a combination thereof, such as a resistor and capacitor 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.

[0043] In one embodiment, the second signal source uses a DC voltage source to convert a DC signal into an AC signal through a switching device under the control of a clock signal.

[0044] In order to better understand the above technical solution, a specific example is provided below.

[0045] like Figure 3 As shown in FIG. 1 , it is a specific example of a detection circuit for voltage measurement circuit parameters. The first signal source of this circuit is set to a power grid. This voltage detection circuit includes a first voltage divider circuit 1 with a reference signal source, a second voltage divider circuit 2, a reference current source circuit, and a voltage measurement module 3 (including a digital-to-analog conversion module and a signal processing module). The first voltage divider circuit 1 is composed of resistors R1, R2, and R3. The reference current source circuit is composed of a reference current source and a switch component SW1 connected in series therewith. This reference current source i ref The frequency is f1 and is different from the grid frequency f0, i ref It is equivalent to being connected in parallel with resistor R3. At the same time, i ref After being connected in parallel with resistor R3, it is connected in series with resistors R2 and R1 in sequence. i0 is an alternating current, and i0=i1+i2. The current flowing through resistors R1, R2, and R3 from the power grid and i1 work together to generate an AC current containing i at the connection point of resistors R1 and R2. ref Information voltage Uo1.

[0046] The second voltage divider circuit 2 is composed of resistors R4, R5, R6 and switch component SW2 in series, where R1 / (R2+R3) is equal to R4 / (R5+R6). The grid voltage becomes Uo2 after passing through the second voltage divider circuit 2. In the analog-to-digital conversion module, analog-to-digital conversion is performed on the analog forms of Uo1 and Uo2 to obtain digital forms of Uo1 and Uo2, and then Uo1 is subtracted from Uo2 to obtain a digital form containing only iref The voltage signal U of the information ref , and finally ref The signal is converted into a digital signal and sent to the signal processing module. The signal processing module is based on U ref The amplitude, phase and other information of the voltage measurement circuit can be used to determine whether the parameters of the voltage measurement circuit have changed, and the voltage measurement value can be compensated and calibrated. The processing method of the signal processing module is the existing technology and will not be described in detail here.

[0047] The second embodiment of the present application relates to an electric energy metering chip, which includes the aforementioned detection circuit. In the embodiment of the present invention, the detection circuit is integrated inside the chip. At this time, the detection circuit inside the chip is not affected by the external environment. Furthermore, the switch state can be set in advance in the voltage measurement module 3 and the switch state can be switched automatically after startup.

[0048] The third embodiment of the present application relates to another electric energy metering chip, such as Figure 2 As shown, the electric energy metering chip includes the first voltage divider circuit 1 and the second voltage divider circuit 2 and the detection circuit. Optionally, the first voltage divider circuit 1 and the second voltage divider circuit 2 are integrated outside the integrated circuit, and other components of the detection circuit are integrated inside the integrated circuit.

[0049] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, article or device including the elements. In the application documents of this patent, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, which includes two situations: performing the action only according to the element, and performing the action according to the element and other elements. Expressions such as multiple, multiple, and multiple include 2, 2 times, 2 kinds, and more than 2, more than 2 times, and more than 2 kinds.

[0050] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teaching content of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A detection circuit for voltage measurement circuit parameters, characterized in that: include A first voltage-dividing circuit (1) coupled to a power grid, a second voltage-dividing circuit (2) connected in parallel with the first voltage-dividing circuit (1), a reference current source circuit, and a voltage measurement module (3); The first voltage divider circuit (1) comprises a resistor R1, a resistor R2 and a resistor R3 which are connected in series in sequence; The reference current source circuit is composed of a reference current source iref and a first switch component SW1 connected in series therewith. The reference current source iref is connected in parallel with the resistor R3 and then connected in series with the resistor R2 and the resistor R1. The second voltage divider circuit (2) comprises a resistor R4, a resistor R5, a resistor R6 and a second switch component SW2 connected in series, wherein R1 / (R2+R3) is equal to R4 / (R5+R6); a connection point between the resistor R1 and the resistor R2 outputs a first voltage signal Uo1 containing information of the reference current source iref, and a connection point between the resistor R4 and the resistor R5 outputs a second voltage signal Uo2; The voltage measurement module (3) comprises an analog-to-digital conversion module, which is used to convert the first voltage signal Uo1 and the second voltage signal Uo2 respectively connected to the analog-to-digital conversion module into digital signals, and to obtain a third voltage signal Uref containing only information about a reference current source iref by subtracting the second voltage signal Uo2 from the first voltage signal Uo1; the voltage measurement module (3) further comprises a signal processing module, which is used to determine whether the parameters of the voltage measurement circuit have changed according to the amplitude and phase of the third voltage signal Uref; wherein the frequency f1 of the reference current source iref is different from the grid frequency f0.

2. An electric energy metering chip, characterized in that: The electric energy metering chip comprises the detection circuit as claimed in claim 1.

3. An electric energy metering chip, characterized in that: In the detection circuit according to claim 1, other components except the first voltage divider circuit (1) and the second voltage divider circuit (2) are arranged in the electric energy metering chip, and the first voltage divider circuit (1) and the second voltage divider circuit (2) are arranged outside the electric energy metering chip.

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