CN101900760A - Electricity meter and power source applicable to same - Google Patents
Electricity meter and power source applicable to same Download PDFInfo
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Abstract
The embodiment of the invention discloses an electronic electricity meter mainly comprising a electricity meter function circuit and a power circuit, wherein the power circuit comprises a switching element, an isolation-power transformer, an input rectifier and filter circuit, an output rectifier and filter circuit and a control and feedback circuit, wherein at least one primary winding and one secondary winding are wound around the same magnetic core of the isolation-power transformer; the primary winding is connected to the input rectifier and filter circuit via the switching element; the secondary winding is connected to the output rectifier and filter circuit; the output rectifier and filter circuit is connected to the electricity meter function circuit; the power-failure signal in the electricity meter function circuit can be acquired from any point in the power circuit; and the power source operates in the switch mode, and the switch state depends on the signal of the control and feedback circuit.
Description
Technical field
The present invention relates to a kind of electronic electricity meter and be used for the power supply of ammeter, relate in particular to a kind of Switching Power Supply electronics ammeter and be used for the Switching Power Supply of ammeter.
Background technology
Electronic electricity meter to the requirement of power supply have following some:
A. input requires: input voltage is generally worked under the 154V-264V condition, and all functions are normal; And power input all has requirement when having or not communication.
B. output requires: carrier communication 12V/0.3A and 5V/0.1A; 485 communication 5V/0.05A; Metering 5V/0.05A.
C.485 must do insulation between communication and other circuit and isolate withstand voltage 4000Vac.
D. laws and regulations requirement: as DL/T614-2007 multifunctional electric energy meter, the general requirement of GB-T17215.211-2008 alternating current measuring equipment etc.).
For a long time, power circuit mainly uses the low frequency linear power supply as the electronic electricity meter power supply in the conditional electronic ammeter, but because of the function of existing electronic electricity meter is become stronger day by day, intellectuality, as remote meter reading, carrier communication, 485 communications etc., requirement to power supply improves gradually, and the conditional electronic ammeter can't solve new problems such as output stability, output power, size, temperature, life-span, energy-conservation and weight.
Fig. 1 is the circuit theory diagrams of existing low frequency linear power supply.The work of tradition low frequency linear power supply gets a low pressure AC2 by electric power network alternating current AC1 input through the low-frequency transformer transformation, and this AC2 voltage gets DC voltage DC1 through rectification and filtering, and this DC1 gets a galvanic current through linear voltage regulator again and presses DC2.
This power work is at the low frequency state, frequency of operation is line voltage frequency (being generally 50Hz), so this transformer size is big and coil turn is a lot, thus this type of transformer fe to undermine copper loss all very big, so low-frequency transformer efficient very low (general 30%-50%); If require output voltage stabilization just must use linear voltage regulator to come regulated output voltage, this will cause output efficiency lower.
And during the work of this type of power supply supply ammeter, because the inherent characteristic of low frequency linear power supply, its output voltage can be done relative linear change with the variation of electrical network input voltage, impel the electric power output voltage job insecurity, when output voltage is lower than the required minimum voltage of ammeter functional circuit operate as normal, directly cause the ammeter can't operate as normal.Referring to Fig. 1 because AC2 voltage is the relation that is directly proportional with input voltage AC1, the AC2 voltage variation that also is directly proportional when input voltage AC1 changes, thus the DC1 voltage after rectification also change, thereby make this voltage pole instability.Therefore the transformer copper loss is big again simultaneously, so the load regulation of output voltage is also very poor.Integrate and see, such electric power output voltage shakiness, input voltage range is little, efficient is low, Heavy Weight is its inherent characteristic.And in limited space, be difficult to realize big output power.Cause simultaneously problems such as temperature height, life-span be short, not energy-conservation again because of efficient is low.
Below illustrate with an example.
Fig. 2 is existing low frequency linear power supply circuit, and this circuit operation is as follows:
Electric power network voltage divides three road AC output after T1 low-frequency transformer transformation.
The first via gets 12VDC voltage (unloaded 15VDC) again to T18, the low AC voltage in 9 pin two ends behind the BD1 rectifier bridge.This 12V voltage divides two-way output, and one the tunnel directly exports, and another road is adjusted to 5V output through the U1 linear voltage regulator.This two-way is exported to the carrier communication circuit and is used.
This road output is unloaded output 15VDC under input 220V condition, and output 9V when adding the 0.15A load is so this road copper loss resistance is 40 ohm (R=(15-9) V/0.15A=40 ohms).When input voltage during at specification lower limit 154V, under the condition of load 0.15A, the carrier communication output voltage only is 4.5V (154V/220V*15V-0.15A*40R=4.5V).And the common regulation carrier communication of standard voltage wants that carrier communication quality is preferably just arranged about 12V, and 4.5V can't satisfy the carrier current channel job requirement at all, causes carrier signal to transmit; Simultaneously power-off signal normally designs when 8V the notification data process chip and does data storage or transmission, must cause the down Monitor Unit circuit working during 4.5V, yet not import under the power-down conditions, and down circuit work is exactly a mistake.Signal deficiency and power down are bad when having carrier communication when therefore this type of power supply supply ammeter is worked.
This table carrier current channel real work electric current is about 0.15A, if guarantee that carrier current channel in specified input voltage (154V-264V) scope, all has high-quality carrier signal, also the power down mistake must not be arranged simultaneously.12VDC output is under the 0.3A loading condition so, guarantee 12V+/-10% voltage output, usually take to strengthen the low-frequency transformer size, directly strengthen thereby the coil turn in the transformer can be increased with line, can reduce the iron loss and the copper loss of transformer like this, improve the output power of this transformer, load regulation has also obtained good improvement simultaneously; If it is just best to re-use a voltage regulator 7812.Voltage output is the precision that can reach 12V+/-5% thus, but the shell of ammeter use at present is standard size, and the method for above-mentioned increasing transformer size is difficult to realize, moreover cost also significantly rises no economic worth.Annotate: 35 transformers of the general use of this type of single-phase electronic electricity meter at present, heavily about 100g, size: L35mm*W35mm*H35mm.
The second the road to T15, the low AC voltage in 6 pin two ends gets 12VDC voltage (zero load) through the D1 rectification again, and this 12V voltage is adjusted to 5V output through the U2 linear voltage, and this road voltage uses to 485 communications.
Third Road gets 12VDC voltage (zero load) through the D2 rectification again to T11, the low AC voltage in 2 pin two ends, and this 12V voltage is adjusted to 5V output through the U3 linear voltage, and this road voltage uses to metering circuit.
As from the foregoing, because the inherent characteristic of low frequency linear power supply when the work of supply ammeter, very easily produces following problem: the 1. bad and communication chip power down of carrier signal transmission that is directed at inadequately of output voltage shakiness, output power; 2. inefficient high energy consumption and the element high temperature that is directed at causes the ammeter life-span to be reduced relatively; 3. for solving above-mentioned 1. 2. problem, must strengthen the model of linear transformer and use high efficiency voltage regulator, thereby the expensive and ammeter standard size that causes is not enough; 4. linear power supply is overweight and oversize, and product is fragile in complex manufacturing that also causes easily and the transportation.Based on electronic electricity meter modular housing specification size, and the constraint of cost, use the low frequency linear power supply, be difficult to solve above problems.
Summary of the invention
In order to solve the above problem of prior art, embodiments of the invention have proposed a kind of Switching Power Supply electronics ammeter and have been used for the switching power circuit of ammeter, and its technical scheme is as follows.
A kind of electronic electricity meter, comprise ammeter power circuit and ammeter functional circuit, this power circuit comprises input rectifying filtering circuit, isolated power transformer and output rectifier and filter, be wound with at least one winding and a Secondary Winding on this magnetic core of transformer, one time winding is connected to the input rectifying filtering circuit, Secondary Winding is connected to output rectifier and filter, output rectifier and filter is connected to the ammeter functional circuit, and the power-off signal in the ammeter functional circuit can obtain more arbitrarily from power circuit.
Described power circuit also comprises exchange component, and one time winding is connected to the input rectifying filtering circuit by exchange component.
Described exchange component is field effect transistor, triode or IGBT constant power semiconductor devices.
Described power circuit also comprises feedbacks and control circuit, feedbacks to be connected to exchange component and output rectifier and filter with control circuit, and obtains back coupling and control signal from output rectifier and filter.
Described ammeter functional circuit comprises carrier communication circuit, 485 telecommunication circuits or metering circuit etc.
Power-off signal in the described ammeter functional circuit obtains more arbitrarily between output rectifier and filter and ammeter functional circuit.
Power-off signal in the described ammeter functional circuit is obtained by the down Monitor Unit circuit, and the down Monitor Unit circuit is located between output rectifier and filter and the ammeter functional circuit.
Described down Monitor Unit circuit comprises the series connection bleeder circuit that at least two resistance are formed.
Power-off signal in the described ammeter functional circuit obtains more arbitrarily between input rectifying filtering circuit and exchange component.
Power-off signal in the described ammeter functional circuit is obtained by the down Monitor Unit circuit after through element separation such as Transformer Winding or photoelectrical couplers, and the down Monitor Unit circuit is located between input rectifying filtering circuit and the exchange component arbitrarily a bit and between the ammeter functional circuit.
Power-off signal in the described ammeter functional circuit obtaining more arbitrarily before the input rectifying filtering circuit.
Obtained by the down Monitor Unit circuit after the element separation such as power-off signal process Transformer Winding in the described ammeter functional circuit or photoelectrical coupler, the down Monitor Unit circuit is located between the preceding a bit any and ammeter functional circuit of input rectifying filtering circuit.
A kind of power circuit that is used for ammeter, comprise input rectifying filtering circuit, exchange component, isolated power transformer and output rectifier and filter, be wound with at least one winding and a Secondary Winding on this magnetic core of transformer, one time winding is connected to the input rectifying filtering circuit by exchange component, Secondary Winding is connected to output rectifier and filter, and output rectifier and filter is connected to the ammeter functional circuit.
Described power circuit also comprises feedbacks and control circuit, feedbacks to be connected to exchange component and output rectifier and filter with control circuit, and obtains back coupling and control signal from output rectifier and filter.
Described power circuit is operated in switching mode, and on off state is by feedbacking and the control signal decision.
Power-off signal in the described ammeter functional circuit can obtain more arbitrarily from power circuit.
Power-off signal in the described ammeter functional circuit is obtained by the down Monitor Unit circuit, the down Monitor Unit circuit is located in the power circuit arbitrarily a bit and between the ammeter functional circuit, obtains that the data processing chip of notice ammeter functional circuit carries out data processing or transmission behind the power-off signal.
Isolated from power power transformer of the present invention is operated in high frequency (the frequency of operation rate is greater than 20KHz) on off state, so the existing relatively electronic electricity meter of the size of this transformer and electronic electricity meter is little a lot, it is much bigger that the power of exporting under identical size condition is also done; So use this power supply can solve that the size that the low frequency linear transformer brings is big, output voltage is unstable and problem such as output power is not enough, make the transmission of ammeter carrier signal stable, and solved communication chip power down problem, simultaneously again therefore power supply than the efficient of linear power supply much higher (this switch power efficiency is greater than 60%), so it is many that the components and parts temperature in the electronic electricity meter has reduced relatively, it is many that life of product and reliability are improved relatively.Power work is at the HF switch state, and the filter capacitor value of this power supply relatively can be little a lot of under the condition that obtains the same output ripple of linear power supply, and cost significantly descends.
Description of drawings
In order to be illustrated more clearly in embodiments of the invention or technical scheme of the prior art, will do to introduce simply to the accompanying drawing of required use in embodiments of the invention or the description of the Prior Art below.
Fig. 1 is the circuit theory diagrams of existing low frequency linear power supply;
Fig. 2 is the circuit diagram of existing low frequency linear power supply;
Fig. 3 is the circuit theory diagrams of the electronic electricity meter that provides of embodiments of the invention;
Fig. 4 is the circuit theory diagrams of the electronic electricity meter that provides of embodiments of the invention;
Fig. 5 is that the present invention is applied to the circuit diagram in the single-phase ammeter;
Fig. 6 is the input voltage waveform figure of electric power network;
Fig. 7 is the oscillogram that the voltage of Fig. 6 obtains behind the input rectifying filtering circuit;
Fig. 8 is the oscillogram that obtains behind the exchange component of voltage via control and feedback loop control of Fig. 7;
Fig. 9 is the oscillogram that the voltage of Fig. 8 obtains through Secondary Winding;
Figure 10 is the oscillogram that the voltage of Fig. 9 obtains behind output rectifier and filter;
Figure 11 is the circuit diagram that obtains power-off signal from the A point between output rectifier and filter and the ammeter functional circuit;
Figure 12 is the circuit diagram that obtains power-off signal from the B point between input rectifying filtering circuit and the exchange component;
Figure 13 is the circuit diagram that the C point before the input rectifying filtering circuit obtains power-off signal.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is carried out clear, complete description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, the every other embodiment that those of ordinary skills do not make creative work and obtained belongs to the scope of protection of the invention.
Referring to Fig. 3 and Fig. 4, electronic electricity meter of the present invention comprises power circuit and ammeter functional circuit 8, and this power circuit comprises input rectifying filtering circuit 1, exchange component 2, isolated power transformer 3, output rectifier and filter 4 and back coupling and control circuit 5.
Exchange component can be field effect transistor, triode or IGBT constant power semiconductor devices.Be wound with at least one winding and a Secondary Winding on the isolated power transformer 3 same magnetic cores, one time winding is connected to input rectifying filtering circuit 1 by exchange component 2, and Secondary Winding is connected to output rectifier and filter 4.Output rectifier and filter 4 is connected to ammeter functional circuit 8.Feedback and be connected to exchange component 2 and output rectifier and filter 4 with control circuit 5, and obtain from output rectifier and filter 4 and to feedback and control signal, feedback and do isolation (being to use the transformer isolation pattern among Fig. 5) with control signal available light electric coupler or transformer.Reference voltage 6 is typically connected to feedbacks and control circuit 5, be used for comparing with back coupling and control signal, the voltage state signal of output rectifier and filter 4 is provided for control circuit, the dutycycle of this signal controlling exchange component 2 and isolated power transformer 3 reaches the voltage purpose of constant output current rectifying and wave filtering circuit 4.The ammeter functional circuit comprises functional circuits such as carrier communication circuit, 485 telecommunication circuits or metering circuit.
Fig. 5 is that the present invention is applied to the circuit diagram in the single-phase ammeter, and this power circuit is operated in switching mode, and on off state is by feedbacking and the control circuit signal deciding.Behind the input rectifying filtering circuit, obtain a dc voltage (waveform such as Fig. 7) by electric power network AC voltage (waveform such as Fig. 6), after being chopped into square wave (waveform such as Fig. 8), the exchange component that this dc voltage is controlled via control and feedback loop again is added on winding of isolated power transformer, be coupled on the Secondary Winding through magnetic core of transformer again, so Secondary Winding obtains and a proportional square wave of winding (Secondary Winding waveform such as Fig. 9), this square wave obtains the dc voltage (waveform such as Figure 10) of needs again behind output rectifier and filter, this dc voltage resupplies the ammeter functional circuit.Constant for the dc voltage that makes this output, the present invention compares by feedback voltage and reference voltage 6, and after control circuit was handled, opening and the turn-off time of control exchange component reached the purpose of constant output.This circuit operation is as follows:
Electric power network AC voltage (waveform such as Fig. 5) is through D1～D4, obtain a dc voltage (waveform such as Fig. 6) behind the input rectifying filtering circuit that C1 forms, this dc voltage is again via IC1, R5, R6, C5, after back coupling that the N5 winding of T1 is formed and control circuit and exchange component are chopped into square wave (waveform such as Fig. 7), be added in (the N2 winding of T1) on winding of isolated power transformer, be coupled to (the N4 winding of T1 on the Secondary Winding through magnetic core of transformer again, the N6 winding, the N7 winding), so Secondary Winding obtains and a proportional square wave of winding (Secondary Winding waveform such as Fig. 8), this square wave obtains the dc voltage (waveform such as Fig. 9) of needs again behind output rectifier and filter, the N4 winding is through D6, get 12VDC voltage behind the current rectifying and wave filtering circuit that C7 forms, this 12V voltage divides two-way output, one the tunnel directly exports, and another road obtains 5V output through the IC2 linear voltage regulator.This two-way is exported to the carrier communication circuit and is used.
The N6 winding gets 8VDC voltage behind the current rectifying and wave filtering circuit that D8, C12 form, this 8V voltage obtains 5V output through the IC4 linear voltage regulator.This road is exported to metering circuit and is used.The N7 winding gets 8VDC voltage behind the current rectifying and wave filtering circuit that D7, C10 form, this 8V voltage obtains 5V output through the IC3 linear voltage regulator, and this road is exported to 485 telecommunication circuits and used.C8, C9 form the filtering circuit of IC2 output 5V voltage, this capacitor C 8 simultaneously, C9 with C7 together for data processing chip provides enough energy after obtaining power-off signal, so that this chip can well be finished data storage or transmission.C11 forms the filtering circuit of IC3 output 5V voltage.C13 forms the filtering circuit of IC4 output 5V voltage.T1 is the isolated power transformer, is operated in the high frequency state, so this transformer size little (5W only for EE1614), efficient height (this power-efficient can reach more than 70%).The N5 winding of T1 is a voltage back coupling winding, because of N4, N5, N6, N7 all on same magnetic core, so the voltage relationship between them is the linear ratio relation, so the voltage on the N5 winding is delivered to IC1 back coupling pin 1 after R5, R6 dividing potential drop, handle the waveform duty cycle on the N2 winding of controlling T1 in the back through IC1, thereby reach the purpose of constant output.This power supply input service voltage is very wide, can accept full voltage 90V～264V input, and output voltage is also very stable.Change and can guarantee that output voltage is constant in+/-5% scope during load variations at the input voltage full voltage.
Power-off signal 7 in the ammeter functional circuit is that electronic electricity meter must carry out monitored signal, if there is not this signal, electronic electricity meter will be lost the data of its measurement, thereby cause the heavy losses of power department, therefore accurately economical to obtain power-off signal 7 extremely important, also is that can this power supply be used for one of crux factor of electronic electricity meter.
Power-off signal 7 of the present invention can obtaining more arbitrarily from power circuit, the down Monitor Unit circuit can be located at the ammeter power circuit arbitrarily a bit and between the ammeter functional circuit, the power-off signal that gets access to by the down Monitor Unit processing of circuit after notice ammeter functional circuit data processing chip I/O mouth carry out data storage or transmission.Below describe with the A point shown in Fig. 3 or Fig. 4, B point and C point respectively:
Embodiment one: obtain power-off signal 7 from the A point between output rectifier and filter and the ammeter functional circuit.
Referring to Figure 11, after the electric power network current interruptions, because of the electric energy of C7 can not in time be replenished, so C7 voltage descends gradually, the down Monitor Unit circuit is done data processing or transmission with this signalisation data processing chip when dropping to certain value, in case measurement data is lost because of power down.
The down Monitor Unit circuit is located between A point and the ammeter functional circuit, realizes that the circuit of down Monitor Unit has a lot of modes, below illustrates with R3, R4 resistance series connection dividing potential drop observation circuit, and its principle of work is as follows:
After the electric power network current interruptions, because of the electric energy on the C1 can not in time be replenished, so the voltage of C1 descends gradually, when C1 voltage drops to certain value, the energy that the transformer of controlling through IC1 transmits can not satisfy keeps the constant of C7 (the C7 anode is the A point) both end voltage, and C7 voltage will descend gradually so.The C7 both end voltage does the power down process signal for data processing chip I/O mouth after the down Monitor Unit circuit sampling that R3, R4, C4 form.
C7 both end voltage Va gets down Monitor Unit signal voltage Vs, Vs=Va*R4/ (R3+R4) after R3, R4 series connection dividing potential drop.C4 is to the Vs signal filtering, prevents that high frequency interference signal from making the data processing chip misoperation.Power-off signal Va generally is designed to smaller or equal to 8V effective, certainly other value of Va voltage also can, do not having under the situation of power down but will satisfy, this principle of power down misoperation can not be arranged under all working state.It is effective that data processing chip I/O mouth generally is designed to low level.The low level threshold voltage is generally 1.25V.So when Va voltage during smaller or equal to 8V, after R3, R4 dividing potential drop, get down Monitor Unit voltage Vs also smaller or equal to 1.25V through C4 filtering again, this Vs voltage is delivered to the data processing chip I/O mouth of ammeter functional circuit, what obtained because of the I/O mouth this moment is low level, so data processing chip will be done data processing or transmission action.
R3, R4 value can be pressed the design of surface current journey method: set power-off signal effective voltage Va value earlier, and effective such as Va8V, determine down Monitor Unit signal effective voltage Vs value again, effective such as Vs1.25V.Selected then R3 or R4 value.Such as earlier selected R4 value 10K, so just can calculate the value of R3, R3=R4* (Va-Vs)/Vs=10* (8-1.25)/1.25=54K.The C4 value selects not have too many requirement.As long as guarantee that Vs voltage not by the high frequency interference, uses 100n just can usually.
Certainly also can with above-mentioned down Monitor Unit to signal do accurately after by comparer and deliver to data processing chip I/O mouth again after the logical process, the present invention does not do one by one and tells about.Obtain power-off signal 7 at the A point in a word, behind the down Monitor Unit circuit, deliver to data processing chip I/O mouth and just can finish this function of monitoring.
Embodiment two: obtain power-off signal 7 from the B point between input rectifying filtering circuit and the exchange component.
Referring to Figure 12, after the electric power network current interruptions, because of the electric energy on the B point reduces gradually, its voltage also descends gradually, and the down Monitor Unit circuit is done data storage or transmission with this signalisation data processing chip when dropping to certain value.In case measurement data is lost because of power down.This signal uses for the down Monitor Unit circuit after generally need using elements such as Transformer Winding or photoelectrical coupler to do isolation.
The down Monitor Unit circuit is located between B point and the ammeter functional circuit, realizes that the circuit of down Monitor Unit has a lot of modes, below the down Monitor Unit circuit formed with R3, photoelectrical coupler PTa and PTb, R4, C4 be the example explanation, its principle of work is as follows:
After the electric power network current interruptions, because of the electric energy on the C1 can not in time be replenished, so the voltage Vb of C1 descends gradually, when this voltage drops to the power down voltage of prior setting, do the power down process signal to data processing chip I/O mouth through the down Monitor Unit circuit sampling back that R3, photoelectrical coupler PTa and PTb, R4, C4 form.
C1 both end voltage Vb gets a marking current Ib through R3, Pta, (Vf in this formula is the forward voltage drop of photoelectrical coupler Pta light emitting diode to Ib=(Vb-Vf)/R3, usually its value is about 1.1V), the electric current I c of Ib control photoelectrical coupler Ptb phototriode, Ic=β * Ib (β in this formula is the transfer rate of this photoelectrical coupler), Ic gets down Monitor Unit signal Vs, Vs=R4*Ic through R4, C4 is to the Vs signal filtering, prevents that high frequency interference signal from making the data processing chip misoperation.In being input as the electronic electricity meter of 220V, power-off signal Vb is designed to smaller or equal to the 90V effective ratio safer, suitable usually.Certainly other value of Vb voltage also can, do not having under the situation of power down but will satisfy, this principle of power down misoperation can not be arranged under all working state.It is effective that data processing chip I/O mouth generally is designed to low level.The low level threshold voltage is generally 1.25V.So when Vb voltage during smaller or equal to 90V, behind R3, photoelectrical coupler PTa and PTb, R4, C4 down Monitor Unit voltage Vs also smaller or equal to 1.25V, this Vs voltage is delivered to data processing chip I/O mouth, what obtained because of the I/O mouth this moment is low level, so data processing chip will be done data processing or transmission action.
R3, R4 value can be pressed the design of surface current journey method: set power-off signal effective voltage Vb value earlier.Effective such as Vb90V.Determine down Monitor Unit signal effective voltage Vs value again.Effective such as Vs1.25V.Selected then R3 or R4 value.Such as earlier selected R3 value 1000K, the transfer rate of photoelectrical coupler is 1, so just can calculate the value of R4, R4=Vs*R3/ (Vb-Vf)/β=1.25*1000/ (90-1.1)/1=14K.The C4 value selects not have too many requirement.As long as protect Vs voltage not by the high frequency interference, use 100n just can usually.
Certainly also can with above-mentioned down Monitor Unit to signal do accurately after by comparer and deliver to data processing chip I/O mouth again after the logical process.Here will not do one by one and tell about.To obtain power down at the B point in a word and press signal, behind the down Monitor Unit circuit, deliver to data processing chip I/O mouth and just can finish this function of monitoring.
Embodiment three: the C point before the input rectifying filtering circuit obtains power-off signal.
Referring to Figure 12, after the electric power network current interruptions, because of being the electric power network direct sample, thus the down Monitor Unit circuit immediately the notification data process chip do data storage or transmission.In case measurement data is lost because of power down.This signal uses for the down Monitor Unit circuit after generally also needing to use elements such as Transformer Winding or photoelectrical coupler to do isolation.
The down Monitor Unit circuit is located between C point and the ammeter functional circuit, realizes that the circuit of down Monitor Unit has a lot of modes, below the down Monitor Unit circuit formed with R3, photoelectrical coupler PTa and PTb, R4, C4 be the example explanation, its principle of work is as follows:
After the electric power network current interruptions, do the power down process signal to data processing chip I/O mouth through the down Monitor Unit circuit sampling back that R3, photoelectrical coupler PTa and PTb, R4, C4 form.Usually this signal concrete grammar of design is such: Vc is through R3, Pta gets a marking current Ib, (Vf in this formula is the forward voltage drop of photoelectrical coupler Pta light emitting diode to Ib=(Vb-Vf)/R3, usually its value is about 1.1V), the electric current I c of Ib control photoelectrical coupler Ptb phototriode, Ic=β * Ib (β in this formula is the transfer rate of this photoelectrical coupler), Ic gets down Monitor Unit signal Vs through R4, Vs=R4*Ic, C4 is to the Vs signal filtering, prevents from also will keep when high frequency interference signal from making the data processing chip misoperation Vs voltage and keeps stable in the regular hour section.In being input as the electronic electricity meter of 220V, power-off signal Vb is designed to smaller or equal to the 90V effective ratio safer, suitable usually.Certainly other value of Vc voltage also can, do not having under the situation of power down but will satisfy, this principle of power down misoperation can not be arranged under all working state.It is effective that data processing chip I/O mouth generally is designed to low level.The low level threshold voltage is generally 1.25V.So when Vb voltage during smaller or equal to 90V, behind R3, photoelectrical coupler PTa and PTb, R4, C4 down Monitor Unit voltage Vs also smaller or equal to 1.25V, this Vs voltage is delivered to data processing chip I/O mouth, what obtained because of the I/O mouth this moment is low level, so data processing chip will be done data processing or transmission action.
R3, R4 value can be pressed the design of surface current journey method: set power-off signal effective voltage Vc value earlier.Effective such as Vc90V.Determine down Monitor Unit signal effective voltage Vs value again.Effective such as Vs1.25V.Selected then R3 or R4 value.Such as earlier selected R3 value 1000K, the transfer rate of photoelectrical coupler is 1, so just can calculate the value of R4, R4=Vs*R3/ (Vb-Vf)/β=1.25*1000/ (90-1.1)/1=14K.The C4 value is selected to require generally to satisfy R4*C4=1T and is got final product (T is a mains frequency).If electrical network is 50Hz, C4=1*20/14=1.4uF.Actual value is wanted to do final value after deviser's experiment.
Above-mentioned down Monitor Unit to signal also can do accurately and deliver to data processing chip I/O mouth again after the logical process by comparer.Here will not do one by one yet and tell about.
To obtain power-off signal at the C point in a word, behind the down Monitor Unit circuit, deliver to data processing chip I/O mouth and just can finish this function of monitoring.This C point can the electrical network L line in Figure 12 on, also on the N line, and the three-phase table also can do sampling in the optional position when using in electrical network, promptly this signal is taken a sample before input rectifying filtering and just can.
Isolated from power power transformer of the present invention is operated in high frequency (the frequency of operation rate is greater than 20KHz) on off state, so the existing relatively electronic electricity meter of the size of this transformer and electronic electricity meter is little a lot, it is much bigger that the power of exporting under identical size condition is also done; So use this power supply can solve that the size that the low frequency linear transformer brings is big, output voltage is unstable and problem such as output power is not enough, make the transmission of ammeter carrier signal stable, and solved communication chip power down problem, simultaneously again therefore power supply than the efficient of linear power supply much higher (this switch power efficiency is greater than 60%), so it is many that the components and parts temperature in the electronic electricity meter has reduced relatively, it is many that life of product and reliability are improved relatively.Power work is at the HF switch state, and the filter capacitor value of this power supply relatively can be little a lot of under the condition that obtains the same output ripple of linear power supply, and cost significantly descends.
Above-mentioned just the present invention typical case in electronic electricity meter one of uses, and the three-phase table is used and just imported the electric network composition difference, so input rectifying filtering circuit connection changes to some extent.Also have the application of some multifunctional meters also similar with last example.The topology of the value of output voltage, group number, output power, component parameters and use Switching Power Supply can need and be decided by actual design when the present invention used, and did not do narration one by one here.
More than disclosed only be several specific embodiment of the present invention, still, the present invention is not limited thereto, the variation that any those skilled in the art considers without creative work all should fall into protection scope of the present invention.
Claims (10)
1. electronic electricity meter, comprise ammeter power circuit and ammeter functional circuit, this power circuit comprises input rectifying filtering circuit, isolated power transformer and output rectifier and filter, be wound with at least one winding and a Secondary Winding on this magnetic core of transformer, one time winding is connected to the input rectifying filtering circuit, Secondary Winding is connected to output rectifier and filter, output rectifier and filter is connected to the ammeter functional circuit, and the power-off signal in the ammeter functional circuit can obtain more arbitrarily from power circuit.
2. electronic electricity meter as claimed in claim 1 is characterized in that described power circuit also comprises exchange component, and one time winding is connected to the input rectifying filtering circuit by exchange component.
3. electronic electricity meter as claimed in claim 2 is characterized in that described exchange component is field effect transistor, triode or IGBT constant power semiconductor devices.
4. electronic electricity meter as claimed in claim 2 is characterized in that described power circuit also comprises back coupling and control circuit, feedbacks to be connected to exchange component and output rectifier and filter with control circuit, and obtains back coupling and control signal from output rectifier and filter.
5. electronic electricity meter as claimed in claim 4 is characterized in that power circuit is operated in switching mode, and on off state is by feedbacking and the control signal decision.
6. electronic electricity meter as claimed in claim 1 is characterized in that described ammeter functional circuit comprises carrier communication circuit, 485 telecommunication circuits or metering circuit.
7. electronic electricity meter as claimed in claim 1 is characterized in that the power-off signal in the described ammeter functional circuit obtains more arbitrarily between output rectifier and filter and ammeter functional circuit.
8. electronic electricity meter as claimed in claim 7 is characterized in that the power-off signal in the described ammeter functional circuit is obtained by the down Monitor Unit circuit, and the down Monitor Unit circuit is located between output rectifier and filter and the ammeter functional circuit.
9. electronic electricity meter as claimed in claim 8 is characterized in that described down Monitor Unit circuit comprises the series connection bleeder circuit that at least two resistance are formed.
10. electronic electricity meter as claimed in claim 8 is characterized in that described down Monitor Unit circuit comprises at least one comparer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010102235855A CN101900760B (en) | 2010-06-25 | 2010-07-07 | Electricity meter and power source applicable to same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| CN201010208897 | 2010-06-25 | ||
| CN201010208897.9 | 2010-06-25 | ||
| CN2010102235855A CN101900760B (en) | 2010-06-25 | 2010-07-07 | Electricity meter and power source applicable to same |
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| Publication Number | Publication Date |
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| CN101900760A true CN101900760A (en) | 2010-12-01 |
| CN101900760B CN101900760B (en) | 2012-02-15 |
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| CN2010102235855A Expired - Fee Related CN101900760B (en) | 2010-06-25 | 2010-07-07 | Electricity meter and power source applicable to same |
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Cited By (8)
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| CN102798756A (en) * | 2012-06-27 | 2012-11-28 | 华立仪表集团股份有限公司 | Power supply circuit for intelligent electricity meter and three-phase intelligent electricity meter |
| CN103913719A (en) * | 2014-04-18 | 2014-07-09 | 国家电网公司 | Method for judging mistaken powering-down fault causes of single-phase carrier intelligent electric meter |
| CN104678168A (en) * | 2015-02-08 | 2015-06-03 | 宜春市脉恩多能科技有限公司 | Miniature power consumption detection device of electric appliance |
| CN105322781A (en) * | 2014-08-27 | 2016-02-10 | 东风汽车电子有限公司 | Power supply module of variable electrical instrument |
| CN105334386A (en) * | 2015-12-07 | 2016-02-17 | 曾子维 | Electric energy measuring system |
| CN112213555A (en) * | 2019-12-20 | 2021-01-12 | 青岛鼎信通讯股份有限公司 | Electric energy meter solution method based on high-speed magnetic isolation communication |
| CN112305305A (en) * | 2020-02-21 | 2021-02-02 | 贵州电网有限责任公司 | Isolation processing system between two cores of modular electric energy meter |
| CN113189536A (en) * | 2021-05-31 | 2021-07-30 | 宁波迦南智能电气股份有限公司 | Power failure detection method and circuit for intelligent meter |
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| CN112305305A (en) * | 2020-02-21 | 2021-02-02 | 贵州电网有限责任公司 | Isolation processing system between two cores of modular electric energy meter |
| CN113189536A (en) * | 2021-05-31 | 2021-07-30 | 宁波迦南智能电气股份有限公司 | Power failure detection method and circuit for intelligent meter |
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| CN101900760B (en) | 2012-02-15 |
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