CN210982711U - Three-phase current detection circuit and electric energy metering chip - Google Patents
Three-phase current detection circuit and electric energy metering chip Download PDFInfo
- Publication number
- CN210982711U CN210982711U CN201921012853.1U CN201921012853U CN210982711U CN 210982711 U CN210982711 U CN 210982711U CN 201921012853 U CN201921012853 U CN 201921012853U CN 210982711 U CN210982711 U CN 210982711U
- Authority
- CN
- China
- Prior art keywords
- coil
- load
- circuit
- phase current
- signal component
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
A three-phase current detection circuit and an electric energy metering chip are disclosed, the three-phase current detection circuit comprises three measurement channels, each measurement channel comprises a coil mutual inductor and a load filter circuit which are coupled with a three-phase alternating current power supply, a primary coil of the coil mutual inductor is coupled with a live wire, the load filter circuit is coupled with a secondary coil, a voltage measurement module is connected on the load filter module in parallel, and each measurement channel further comprises a correction coil wound on a magnetic core of the coil mutual inductor; a first signal source input on the correction coil; the voltage measurement module is used for detecting a first signal component of the second frequency on the load filter circuit and determining whether circuit parameters of the load filter circuit and the secondary coil are abnormal or not according to the first signal component.
Description
Technical Field
The application belongs to the technical field of voltage detection, and particularly relates to a three-phase current detection circuit and an electric energy metering chip.
Background
In the current three-phase current measuring device, three-phase currents to be measured are respectively attenuated to reasonable values through a sampling network of three coil transformers, then the currents to be measured are converted into voltages to be measured after the currents flow through resistors outside a chip, the converted voltages to be measured are filtered outside the chip and then are sent to an input end of an Analog to digital converter (ADC), and digital outputs after the conversion of the ADC enter a digital processing unit to perform voltage amplitude and phase processing. In high-precision measurement (such as power facility monitoring and electricity utilization statistics), the precision requirement on a metering instrument reaches +/-0.5%. This requires sufficient stability in the accuracy of the off-chip coil transformer, the resistors used to convert the circuit under test to the voltage under test, the filter network and the voltage measurement channel.
However, the conventional three-phase current measurement method cannot monitor the three-phase current from time to ensure the accuracy of the three-phase current measurement. The accuracy depends on selecting an off-chip component with good temperature coefficient and high accuracy, and the off-chip high-accuracy component can be changed under the conditions of different external forces, such as high and low temperature, static electricity, overvoltage, surge and the like, so that the transmission function of a three-phase current measurement channel is changed, the three-phase current measurement error is caused, and the error of electric energy metering is further caused by combining with voltage measurement.
Disclosure of Invention
The application aims to provide a three-phase current detection circuit and an electric energy metering chip, and aims to solve the problem that the traditional three-phase current measurement circuit cannot detect the problem that the external component parameter transformation caused by the influence of external force causes measurement error and voltage measurement precision reduction.
A first aspect of the present application provides a three-phase current detection circuit, including three measurement channels, each of the measurement channels includes a coil transformer and a load filter circuit coupled with a three-phase ac power source having a first frequency, the coil transformer includes a magnetic core, and a primary coil and a secondary coil coupled with each other, the primary coil is coupled with a live wire, the load filter circuit is coupled with the secondary coil, and a voltage measurement module is connected in parallel to the load filter circuit, and is characterized in that each of the measurement channels further includes a correction coil wound around the magnetic core of the coil transformer; the three-phase detection circuit further comprises a first signal source with a second frequency and input on the correction coil; the voltage measuring module is used for detecting a first signal component of the second frequency on the load filter circuit and determining whether circuit parameters of the load filter circuit and the secondary coil are abnormal or not according to the first signal component.
A second aspect of the present application is to provide an electric energy metering chip, which includes the above-mentioned detection circuit; the coil mutual inductor, the correction coil and the load filter circuit are arranged outside the electric energy metering chip.
A third aspect of the present application provides an electric energy metering chip, which includes a load filter circuit, and the electric energy metering chip further includes the above-mentioned detection circuit.
The above-mentioned three-phase voltage detection circuit and method introduce the extra signal source through a correction coil in the conventional voltage measurement channel, position the chip outer assembly with the help of the known information of the alternating current signal source: and whether the load filter circuit and the secondary coil have faults or not is judged, so that the function of accurately positioning a fault source is achieved.
Drawings
Fig. 1 is a schematic circuit diagram of a three-phase current detection circuit provided in an embodiment of the present application;
fig. 2 is a schematic diagram of an exemplary circuit of a load filtering module in the three-phase current detection circuit shown in fig. 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1, the three-phase current detection circuit provided in the embodiment of the present application includes three measurement channels for measuring electrical parameters of three live lines 117/118/119 connected between a three-phase ac power source 115 and a load 116, respectively. Taking one of the measurement channels as an example, the measurement channel includes a coil transformer 103 coupled to a three-phase alternating current power source having a first frequency and a load filter circuit 400.
The coil transformer 103 comprises a magnetic core 106, a primary coil 107 and a secondary coil 108 which are coupled with each other, the primary coil 107 is coupled with one live wire 117, a load filter circuit 400 is coupled with the secondary coil 108, a voltage measuring module 200 is connected to the load filter circuit 108 in parallel, and each measuring channel further comprises a correction coil 121 wound on the magnetic core of the coil transformer 103; the three-phase detection circuit further includes a first signal source 308 having a second frequency, input at the correction coil 121; the voltage measurement module 200 is configured to detect a first signal component of a second frequency on the load filter circuit 400, and determine whether a circuit parameter of the load filter circuit 400 and the secondary coil 108 is abnormal according to the first signal component.
The first signal source 308 is an alternating current signal source, and can be switched on or off the correction coil 121 under the control of a switch, and the first signal sources 308 on each measurement channel can share one signal source or use different signal source circuits; the correction coils 121 on each measurement channel are connected in series, or in parallel. The frequency of the first signal source 308 is different from the frequency of the three-phase alternating current being measured, and the second frequency is a non-integer multiple of the first frequency. For example, when the frequency of the measured three-phase ac current is 50Hz, the second frequency may be selected to be 432 Hz. The first signal source 308 is a current source generated by a combination of a reference voltage source, an operational amplifier, a current mirror and a feedback resistor. The internal circuit of the actual current source can control the output waveform of the current source to be an alternating current signal through a switch. The first signal source 308 may also be a voltage signal source that generates a sensing current through a resistor that flows through the calibration coil 121.
The correction coil 121 is wound around the core of the coil transformer 103, and may be located on one side of the primary coil 107 or on one side of the secondary coil 108. The correction coil 121 of the embodiment shown in fig. 1 is located on the secondary coil 108 side. The voltage measurement module 200 includes an analog-to-digital conversion unit 201 and digital signal processing units 204, 205, and the voltage measurement module 200 functions as both a measurement signal processing unit and a detection signal processing unit.
In an embodiment, the voltage measurement module 200 is specifically configured to process the first signal component, obtain an amplitude value and a phase value of the first signal component, and determine whether the circuit parameter is abnormal according to a change in the amplitude value and/or a change in the phase of the first signal component.
Further, the voltage measurement module 200 is further configured to detect a second signal component of the first frequency on the load filter circuit 400, calibrate a circuit parameter according to the first signal component and the second signal component, and perform voltage measurement.
The feedback resistor used in the signal source generating circuit of the first signal source 308 is the same as the device temperature coefficient of the load filter circuit 400, and the temperature coefficient of the measurement channel load filter circuit 400 can be cancelled by the temperature coefficient of the feedback resistor. Thus, the feedback resistor of the first signal source 308 can be placed off-chip, and an ac current source with any temperature coefficient can be obtained by selecting an off-chip resistor with any temperature coefficient.
In one embodiment, referring to fig. 2, the load filter circuit 400 includes a load module 410 and a filter module 420, the load module 410 is connected to two ends of the secondary winding 108, and the load module 410 converts a current signal output by the secondary winding 108 into a voltage signal; the filtering module 420 is connected to both ends of the load module 410, and the filtering module 420 filters the voltage signal and outputs a first signal component or a second signal component.
The load module 410 includes a first load 412 and a second load 414 connected in parallel across the secondary winding 108, and the connection terminals of the first load 412 and the second load 414 are grounded. The filter module 420 includes a first current limiting resistor 421, a second current limiting resistor 422, a first filter capacitor 423, and a second filter capacitor 424, the first current limiting resistor 421 is connected in series between one end of the secondary winding 108 and the first input end of the voltage measurement module 200, and the second current limiting resistor 422 is connected in series between the other end of the secondary winding 108 and the second input end of the voltage measurement module 200; the first filter capacitor 423 is connected in series between the first input terminal of the voltage measurement module 200 and ground, and the second filter capacitor 424 is connected in series between the second input terminal of the voltage measurement module 200 and ground. The first load 412 and the second load 414 are both circuits composed of at least one of a resistor, an inductor, and a capacitor.
Referring to fig. 1 and 2, each of the measuring channels includes three identical signal processing units 100/101/102 of the load filter circuit 400 and the voltage measuring module 200, which are respectively used for measuring the current in three live wires 117/118/119 of the three-phase alternating current. On the first measurement channel, the load module 410 converts the current output by the secondary winding 108 into a voltage, and then the voltage is sent to the voltage measurement module 200 through the filter module 420 to obtain a measured value of the current after processing.
Specifically, the currents of the first signal source 308 respectively flow through the calibration coils 121 of the three coil transformers 103/104/105, the detection currents are sent to the input end of the signal processing unit 100/101/102 through the coil transformers 103/104/105, the signal processing unit 100/101/102 generates the measured values of the detection signals after processing, and when the device characteristics of the coil secondary coils 108/111/114 in the three coil transformers 103/104/105 or the load filter circuit 400 change, the amplitude and the phase of the measured values of the detection signals correspondingly change, so that the error of the three-phase current measurement channel is determined.
The error detection method of the three live wire current measurement channels in the three-phase current measurement is similar, and the error detection of the current measurement channel in one of the live wires 117 is taken as an example for explanation.
First, assume that the turn ratio of the correction coil 121 and the secondary coil 108 through which the correction current flows in the coil transformer 103 is M: n, fire line 117 correction line in coil inductor 103The correction current flowing through the loop 121 is IedtThe voltage at the input of the voltage measurement module 200 is Vedt_ADCThen V can be calculatededt_ADCComprises the following steps:
wherein R is412Is the resistance value, R, of the first load 412421Is the resistance value, C, of the first current limiting resistor 421423The capacitance value of the first filter capacitor 423, s is the frequency.
When the parameters of the load filter circuit 400 change, the voltage amplitude a and the phase of the voltage input to the analog-to-digital conversion unit 201
Variations will also occur. So that the error value of this current measurement channel can be known. When the secondary winding 108 is abnormal, the turn ratio M: N is also changed, so that the amplitude a and the phase Φ of the voltage input to the analog-to-digital conversion unit 201 are also changed. So that the error value of the current measurement channel can be known
The error detection modes of the current measurement channels of the other two live wires 118/119 are similar to the error detection mode of the current measurement channel of the live wire 117, so that the error detection of three-phase current measurement channels can be realized through one detection signal source 308 and one correction coil 121. The current source can be implemented on-chip, which greatly reduces the design complexity.
The voltage measurement module 200 is an on-chip device of the integrated circuit, and the feedback resistances of the load filter module 400 and the first signal source 308 are off-chip devices of the integrated circuit. The load filter module 400 is not limited to the impedance type, and may be an impedance such as a resistor, a capacitor, or an inductor, or a combination thereof, for example, an impedance such as a parallel connection of a resistor and a capacitor. If the sampling network comprises components such as capacitors and inductors, the fault source can be positioned by monitoring the amplitude and phase change of the detection signal at the same time.
In addition, a three-phase current detection method is also disclosed, which comprises the following steps:
loading a three-phase alternating current power supply with a first frequency at two ends of a load filter circuit in a magnetic induction coupling mode; the load filter circuit is connected with a secondary coil of a coil transformer, and a primary coil of the coil transformer is coupled with the three-phase alternating current power supply;
loading a first signal source with a second frequency on the coil transformer through a correction coil;
detecting a first signal component at the second frequency on the load filter circuit;
and determining whether the circuit parameter of the load filter circuit is abnormal according to the first signal component.
In one embodiment, the determining whether a parameter of the load filter circuit is abnormal according to the first signal component specifically includes:
and processing the first signal component to respectively obtain an amplitude value and a phase value of the first signal component, and determining whether the circuit parameter is abnormal according to the amplitude value change and/or the phase change of the first signal component.
In one embodiment, the method further comprises the following steps:
detecting a second signal component at the first frequency on the load filter circuit;
and calibrating the circuit parameters according to the first signal component and the second signal component, and carrying out voltage measurement.
The embodiment of the application also provides an electric energy metering chip which comprises the detection circuit. In the embodiment of the application, the coil transformer, the correction coil and the load filter circuit are arranged outside the electric energy metering chip.
The embodiment of the application also provides another electric energy metering chip, which comprises a load circuit and the detection circuit.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (11)
1. A three-phase current detection circuit comprises three measurement channels, wherein each measurement channel comprises a coil transformer and a load filter circuit which are coupled with a three-phase alternating current power supply with a first frequency, the coil transformer comprises a magnetic core, and a primary coil and a secondary coil which are coupled with each other, the primary coil is coupled with a live wire, the load filter circuit is coupled with the secondary coil, and a voltage measurement module is connected with the load filter circuit in parallel; the three-phase current detection circuit further comprises a first signal source with a second frequency and input to the correction coil; the voltage measuring module is used for detecting a first signal component of the second frequency on the load filter circuit and determining whether circuit parameters of the load filter circuit and the secondary coil are abnormal or not according to the first signal component.
2. The three-phase current detection circuit according to claim 1, wherein the voltage measurement module is specifically configured to process the first signal component to obtain an amplitude value and a phase value of the first signal component, and determine whether the circuit parameter is abnormal according to a change in the amplitude value of the first signal component and/or a change in the phase of the first signal component.
3. A three-phase current detecting circuit according to claim 1, wherein the correction coil is wound on one side of a primary coil or one side of a secondary coil of the coil transformer.
4. The three-phase current sensing circuit of claim 1, wherein the voltage measurement module is further configured to sense a second signal component at the first frequency on the load filter circuit, calibrate the circuit parameter based on the first signal component and the second signal component, and perform a voltage measurement.
5. A three-phase current sensing circuit according to any of claims 1 to 4, wherein said load filtering circuit comprises:
the load module is connected with two ends of the secondary coil and converts a current signal output by the secondary coil into a voltage signal;
and the filtering module is connected with two ends of the load module and filters and outputs the voltage signal.
6. A three-phase current sensing circuit according to claim 5, wherein said load module includes a first load and a second load connected in parallel across said secondary winding, the connection of said first load and said second load being connected to ground.
7. The three-phase current detection circuit according to claim 5, wherein the filter circuit comprises a first current limiting resistor, a second current limiting resistor, a first filter capacitor, and a second filter capacitor, the first current limiting resistor is connected in series between one end of the secondary coil and the first input terminal of the voltage measurement module, and the second current limiting resistor is connected in series between the other end of the secondary coil and the second input terminal of the voltage measurement module; the first filter capacitor is connected between the first input end of the voltage measurement module and the ground in series, and the second filter capacitor is connected between the second input end of the voltage measurement module and the ground in series.
8. A three-phase current sensing circuit according to claim 1, wherein said first signal source is an alternating current source and said second frequency is a non-integer multiple of said first frequency.
9. The three-phase current sensing circuit of claim 1, wherein the voltage measurement module is an on-chip device of an integrated circuit, and the feedback resistors used in the coil transformer, the correction coil, the load filter circuit, and the generation circuit of the first signal source are off-chip devices of the integrated circuit.
10. An electric energy metering chip, characterized in that the electric energy metering chip comprises a three-phase current detection circuit according to any one of claims 1 to 9; the coil mutual inductor, the correction coil and the load filter circuit are arranged outside the electric energy metering chip.
11. An electric energy metering chip comprising a load filter circuit, characterized in that it further comprises a three-phase current detection circuit according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921012853.1U CN210982711U (en) | 2019-06-28 | 2019-06-28 | Three-phase current detection circuit and electric energy metering chip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921012853.1U CN210982711U (en) | 2019-06-28 | 2019-06-28 | Three-phase current detection circuit and electric energy metering chip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210982711U true CN210982711U (en) | 2020-07-10 |
Family
ID=71422971
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921012853.1U Active CN210982711U (en) | 2019-06-28 | 2019-06-28 | Three-phase current detection circuit and electric energy metering chip |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN210982711U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110221239A (en) * | 2019-06-28 | 2019-09-10 | 深圳市锐能微科技有限公司 | Three-phase current detection circuit, method and electric energy computation chip |
-
2019
- 2019-06-28 CN CN201921012853.1U patent/CN210982711U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110221239A (en) * | 2019-06-28 | 2019-09-10 | 深圳市锐能微科技有限公司 | Three-phase current detection circuit, method and electric energy computation chip |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10139432B2 (en) | Methods and systems relating to improved AC signal performance of dual stage transformers | |
| US7622910B2 (en) | Method and apparatus for AC integrated current sensor | |
| US10436821B2 (en) | Apparatus for detecting AC components in a DC circuit and use of the apparatus | |
| US7521916B2 (en) | Apparatus for the detection of a current and method for operating such an apparatus | |
| US10078102B2 (en) | Methods and devices for AC current sources, precision current transducers and detectors | |
| US9063178B2 (en) | System for measuring current and method of making same | |
| CN110007133B (en) | Digital AC/DC current sensor and current detection method | |
| WO2021111238A1 (en) | Self calibration by signal injection | |
| CN210982711U (en) | Three-phase current detection circuit and electric energy metering chip | |
| EP1923709B1 (en) | Active linear current transducer | |
| CN113517122B (en) | PCB type current transformer with correction function | |
| EP3116001A1 (en) | Impedance-compensated current transformer | |
| JP2020204524A (en) | Current sensor and measuring device | |
| RU2428705C1 (en) | Measuring negative sequence current converter | |
| CN210982710U (en) | Detection circuit for parameters of voltage division circuit and electric energy metering chip | |
| CN210720563U (en) | Current sampling device | |
| Zhu et al. | A wide bandwidth, on-line impedance measurement method for power systems, based On PLC techniques | |
| Xiaohua et al. | Improved performance Rogowski coils for power system | |
| CN108732415B (en) | AC sensor and circuit breaker | |
| MORENO et al. | IEC 61869–10 and IEC 61869–11 Passive Sensors and their Interface with IEDS | |
| US11892474B2 (en) | Universal measurement input for connecting a small signal transformer and electrical device with such a measurement input | |
| CN110221239A (en) | Three-phase current detection circuit, method and electric energy computation chip | |
| CN217404394U (en) | Protection and measurement dual-purpose high-precision large-dynamic-range alternating current sampling circuit | |
| JPH0747741Y2 (en) | Capacitive voltage transformer with terminals for harmonic measurement | |
| RU2575140C1 (en) | Differential current measurement device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |