CN203249946U - Three-phase keyboard type electric energy meter - Google Patents
Three-phase keyboard type electric energy meter Download PDFInfo
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- CN203249946U CN203249946U CN 201320317125 CN201320317125U CN203249946U CN 203249946 U CN203249946 U CN 203249946U CN 201320317125 CN201320317125 CN 201320317125 CN 201320317125 U CN201320317125 U CN 201320317125U CN 203249946 U CN203249946 U CN 203249946U
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Abstract
The utility model discloses a three-phase keyboard type electric energy meter. The electric energy meter comprises an MCU, relays provided with shunts, pre-stage filter circuits, signal processing front terminal ICs, isolation transformers and EMI circuits. An A-phase live wire, a B-phase live wire, a C live wire are respectively connected to the input terminal of each front contact corresponding to each relay by the relays provided with the shunts. The current output terminal of each shunt is connected to the signal input terminal of each signal processing front terminal IC through the filter circuit. The signal output terminal of each signal processing front terminal IC is connected the current sampling differential input terminal by each isolation transformer in series with each EMI circuit. The electric energy meter is direct current saturation resistant, strong magnetism resistant, and is of small size and light weight. By employing the electric energy meter, the reliability is improved, the precision of the electric energy meter in a whole temperature range is raised, the electromagnetic compatibility of the electric energy meter is improved, and the cost is reduced effectively.
Description
Technical field
The utility model relates to a kind of electric energy meter, particularly a kind of three-phase keyboard-type electric energy meter.
Background technology
Present most electric energy meter Development and Production enterprise has all adopted the circuit of three current transformers (often being called CT in the practical application for short) in three-phase meter, the schematic block circuit diagram of this electric energy meter as shown in Figure 2, A, B, C three-phase current flow through respectively the primary side of current transformer separately, current transformer is input to various signal sampling chips or MCU with secondary side through the small-signal current simulating signal after the conversion, obtain simultaneously voltage signal, then analytic operation obtains the required various measurement data of electric energy meter.
Although this scheme has solved the problem of isolating between the three-phase, still exist some problems:
1. because current transformer adopts is the electromagnetism transform principle, the magnetic saturation situation easily occurs, thereby produce serious measured deviation;
2. current transformer also is easy to be subject to outside strong magnetic interference and few quantity calculation, and then the stealing situation occurs;
3. the current sample device in the in the past design and separately design of relay, contact resistance is large, and reliability is not high, and is bulky, and weight is heavier, and difficulty is installed;
4. the precision of electric energy meter changes larger in whole temperature range.
The utility model content
The purpose of this utility model provides a kind of reliable and anti-interference strong three-phase keyboard-type electric energy meter.
This three-phase keyboard-type electric energy meter that the utility model provides, comprise MCU, relay with shunt, the prime filtering circuit, signal is processed front end IC, isolating transformer and EMI circuit, the A phase firewire of three-phase electricity, B phase firewire and C phase firewire are respectively by linking to each other with the input end of corresponding each moving together contact of described relay with each shunt in the relay of shunt, the signal input part that the current output terminal of described shunt is processed front end IC by prime filtering circuit and signal links to each other, and the signal output part that signal is processed front end IC links to each other with the current sample differential input end of MCU by isolating transformer series connection EMI circuit.
Three described shunts adopt hard connection directly to weld together between the input end of corresponding three pairs of moving together contact respectively with in the described relay.The current output terminal of three described shunts all directly is welded on the PCB; The welding position of three described signal processing front end IC all is close to the separately welding position place of described shunt on PCB.Described signal is processed front end IC and is comprised pre-amplification circuit, analog to digital conversion circuit and high frequency modulated circuit.
The utility model can resist saturated, the anti-strong magnetic of direct current, volume little, lightweight, and has reduced cost.A phase, B phase, C phase three-phase sample circuit can be realized electrical isolation easily; Adopted the integrated design of shunt and relay, adopted hard connection directly to weld together between the two, reduced contact resistance, improved reliability, the installation in also being convenient to show and the reduction of cost.The utility model can also be monitored the temperature of shunt, terminal row, is more convenient for carrying out temperature compensation and control, has improved the precision of electric energy meter in whole range of temperature, also is convenient to improve simultaneously the Electro Magnetic Compatibility of ammeter.
Description of drawings
Fig. 1 is a kind of embodiment figure of the present utility model.
Fig. 2 is the circuit theory diagrams of prior art scheme.
Embodiment
As shown in Figure 1, the utility model comprises MCU, the relay with shunt, prime filtering circuit, signal processing front end IC, isolating transformer and EMI circuit, and the A phase firewire of three-phase electricity, B phase firewire and C phase firewire are respectively by linking to each other with the input end of the corresponding moving together contact of this relay with each shunt in the relay of shunt.The signal input part that the current sample output terminal of this shunt is processed front end IC by prime filtering circuit and signal links to each other, and the signal output part that signal is processed front end IC links to each other with the current sample differential input end of MCU by isolating transformer series connection EMI circuit.
From the current signal that this shunt obtains, process front end IC through signal and carry out signal amplification and analog to digital conversion, then be modulated into high-frequency digital signal, be transferred to MCU by isolating transformer again; MCU decodes to this signal, obtains signal proportional to input current, and then carries out together analytic operation in conjunction with voltage signal, finally obtains the data such as the required power of electric energy meter, phase place, electric weight.
The utility model adopts shunt, signal processing front end and isolating transformer to realize sampling and the transmission of three-phase current signal, has the function of saturated, the anti-strong magnetic of anti-direct current.
Specific works mode of the present utility model is as follows:
Specifically analyze with the A circuitry phase, the circuit theory of B phase, C phase is mutually identical with A.
After the A phase firewire is input to three-phase meter, at first process is with the shunt SHUNT_A in the relay of shunt, draw 220V voltage (with respect to zero line N) to A phase voltage potential-divider network from the voltage output end of this shunt SHUNT_A, obtain afterwards decaying into hundreds of millivolts voltage sampling signal, be entered into MCU.The A phase current is by the shunt SHUNT_A of tens of micro-ohms, between the current sample output terminal IA+ of this shunt and current sample output terminal IA-, produce voltage difference, so first current signal is transformed into voltage signal, enters into signal through the prime filtering circuit afterwards and process front end IC(AEF_A) input anode INP, two signal input pins of input negative terminal INN.Process the inside of front end IC at signal and first this signal is carried out preposition amplification, then be transformed into digital signal through inner ADC, high frequency modulated circuit by inside modulates the signal on the high frequency carrier of MHz level again, process output plus terminal SP, two signal output pin outputs of output negative terminal SN of front-end A EF_A from this signal, then through isolating transformer TA, after passing through again the EMI circuit, this signal is transferred to current sample differential input end IAP, two differential signal input pins of current sample differential input end IAN of MCU.MCU decodes to the voltage and current signal that input is come in, obtain and input voltage, the proportional signal of input current, it is carried out analytic operation, finally obtain the various electric quantity datas such as required active power, reactive power, phase place, frequency, power factor.
Signal is processed front end IC and is comprised pre-amplification circuit, analog to digital conversion circuit and high frequency modulated circuit.
The prime filtering circuit comprises inductance L 1A, inductance L 2A, capacitor C 1A, capacitor C 2A, capacitor C 3A, resistance R 1A, resistance R 2A.Inductance L 1A and inductance L 2A are connected to respectively current sample output terminal IA+ and the current sample output terminal IA-of shunt SHUNT_A, be connected between current sample output terminal IA+ and the current sample output terminal IA-after capacitor C 1A and the capacitor C 2A series connection, tie point place ground connection in the middle of this two electric capacity, resistance R 1A be connected between current sample output terminal IA+ and the current sample output terminal IA-after resistance R 2A connects; Capacitor C 3A is connected between current sample output terminal IA+ and the current sample output terminal IA-.
The EMI circuit comprises isolating transformer primary side resistance R 3A, isolating transformer primary side resistance R 4A, isolating transformer secondary resistance R5A, isolating transformer secondary resistance R6A and rear class filtering circuit.Isolating transformer primary side resistance R 3A, isolating transformer primary side resistance R 4A are connected to signal and process between front end IC and the isolating transformer TA; The two ends of the secondary side of isolating transformer TA link to each other with the rear class filtering circuit after respectively being connected in series respectively isolating transformer secondary resistance R5A, isolating transformer secondary resistance R6A; The rear class filtering circuit links to each other with the current sample differential input end of MCU.The rear class filtering circuit comprises capacitor C 5A, capacitor C 6A, capacitor C 7A; Capacitor C 5A is connected between current sample differential input end IAP, the current sample differential input end IAN of MCU.Be connected between current sample differential input end IAP, the current sample differential input end IAN of MCU the tie point place ground connection in the middle of this two electric capacity after capacitor C 6A and the capacitor C 7A series connection.Conduction and radiated noise that this circuit is used for suppressing for other equipment disturb, and satisfy domestic and international various test request.
Signal flow and the principle of B phase, C phase are mutually identical with A.Because the electric current of A phase, B phase, C phase three-phase is input to MCU simultaneously, therefore can measure and calculate the phase relation between the three-phase current.Have the current signal of A phase, B phase, C phase three-phase of high voltage differential very respectively through after the isolating transformer TA, the isolating transformer TB that link to each other separately, the isolating transformer TC, just can connect altogether.
Isolating transformer TA can transmitting high-frequency signal, even if each does not have electric current mutually, MCU and signal are processed front end IC(AEF_A) between the high-frequency impulse transmission is also arranged, process signal processing front end IC(AEF_A) inner rectifier obtains working power, well solved the problem that power supply is supplied with, and need not to increase in addition more numerous and diverse A phase, B phase, C mutually in the power supply of each phase current sampling circuit.
All keyboard tables nearly all need to carry out break-make control according to dump energy and power load for user's power supply, therefore in the table the built-in relay of large electric current is arranged nearly all, how being electrically connected shunt and relay with structural design also is one of difficult point, if separately design, connect by screw, then increase the whole thermal value of ammeter, the ammeter temperature rise is very high, also reduce simultaneously the stability of ammeter, also increased the installation difficulty when ammeter is produced.
Shunt of the present utility model and relay design are as a whole, and adopt hard connection directly to weld together between the two: in three shunts in access A phase, B phase, the C circuitry phase and the relay between the input end of each corresponding moving together contact the hard connection of employing directly weld together, reduced contact resistance, improved reliability, the installation in also being convenient to show and the reduction of cost.This shunt adopts precision electrical resistance alloy, can use in wider working range, and thermotolerance is better, and inductance value is little, and saturated, the anti-strong magnetic of anti-direct current, volume are little, lightweight, and cheap, more and more use on sampling resistor at present.
The three-phase keyboard table is interior because the built-in heterogeneous relay of large electric current is installed at present, because the contact contact resistance of built-in relay, in the situation that it is larger in load to work long hours, the table internal heat generation is larger, directly have influence on the components and parts in the table, cause precision to produce drift.Be controlled in the little scope of trying one's best for precision is changed, must obtain the temperature of ammeter relevant position, in order to carry out the compensation about precision and clock.Even some customer requirement is when end of incoming cables temperature in the table is high when arriving certain numerical value, in order to guarantee safety, needs the relay cut-out electric current that temporarily trips.How to obtain and actual consistent temperature, be one of difficult point always.
The utility model directly is welded on the current output terminal of shunt on the PCB, rather than connect by flexible circuit conductor, and be connected to respectively the A phase, the B phase, three signals of C phase are processed front-end A FE_A, signal is processed front-end A FE_B, signal is processed front-end A FE_C, these three signals are processed front ends and all are close to welding position on the shunt place PCB separately, can accurately obtain like this, and then the temperature of monitoring shunt and terminal row, be more convenient for carrying out temperature compensation and control, improve the precision of ammeter in whole temperature range, also be convenient to improve simultaneously the Electro Magnetic Compatibility of ammeter.
A, B, C three-phase can adopt identical signal sampling and transmission circuit and be independent of each other, and reduce design difficulty, have also reduced part category.Three cover circuit are identical, and all volume is very little, very light in weight.
Claims (4)
1. three-phase keyboard-type electric energy meter, comprise MCU, it is characterized in that, this electric energy meter also comprises the relay with shunt, the prime filtering circuit, signal is processed front end IC, isolating transformer and EMI circuit, the A phase firewire of three-phase electricity, B phase firewire and C phase firewire are respectively by linking to each other with the input end of corresponding each moving together contact of described relay with each shunt in the relay of shunt, the signal input part that the current output terminal of described shunt is processed front end IC by prime filtering circuit and signal links to each other, and the signal output part that signal is processed front end IC links to each other with the current sample differential input end of MCU by isolating transformer series connection EMI circuit.
2. three-phase keyboard-type electric energy meter according to claim 1 is characterized in that, three described shunts adopt hard connection directly to weld together between the input end of corresponding three pairs of moving together contact respectively with in the described relay.
3. three-phase keyboard-type electric energy meter according to claim 1 is characterized in that, the current output terminal of three described shunts all directly is welded on the PCB; The welding position of three described signal processing front end IC all is close to the separately welding position place of described shunt on PCB.
4. three-phase keyboard-type electric energy meter according to claim 1 is characterized in that, described signal is processed front end IC and comprised pre-amplification circuit, analog to digital conversion circuit and high frequency modulated circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320317125 CN203249946U (en) | 2013-06-04 | 2013-06-04 | Three-phase keyboard type electric energy meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320317125 CN203249946U (en) | 2013-06-04 | 2013-06-04 | Three-phase keyboard type electric energy meter |
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| Publication Number | Publication Date |
|---|---|
| CN203249946U true CN203249946U (en) | 2013-10-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320317125 Expired - Lifetime CN203249946U (en) | 2013-06-04 | 2013-06-04 | Three-phase keyboard type electric energy meter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103777100A (en) * | 2014-01-28 | 2014-05-07 | 刘兵 | Device and method for acquiring electricity utilization information |
| CN108254600A (en) * | 2018-02-23 | 2018-07-06 | 南京飞腾电子科技有限公司 | Electric energy meter |
| CN114994382A (en) * | 2022-07-14 | 2022-09-02 | 北京智芯半导体科技有限公司 | Temperature compensation method and device for electric energy metering, electric energy metering device and medium |
-
2013
- 2013-06-04 CN CN 201320317125 patent/CN203249946U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103777100A (en) * | 2014-01-28 | 2014-05-07 | 刘兵 | Device and method for acquiring electricity utilization information |
| EP3128334A4 (en) * | 2014-01-28 | 2017-12-20 | Bing Liu | Apparatus and method for obtaining power usage information |
| CN108254600A (en) * | 2018-02-23 | 2018-07-06 | 南京飞腾电子科技有限公司 | Electric energy meter |
| CN114994382A (en) * | 2022-07-14 | 2022-09-02 | 北京智芯半导体科技有限公司 | Temperature compensation method and device for electric energy metering, electric energy metering device and medium |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131023 |