CN201523324U - Insulating RS485 power supply circuit for electric energy meter and pulse transformer thereof - Google Patents
Insulating RS485 power supply circuit for electric energy meter and pulse transformer thereof Download PDFInfo
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- CN201523324U CN201523324U CN200920271635XU CN200920271635U CN201523324U CN 201523324 U CN201523324 U CN 201523324U CN 200920271635X U CN200920271635X U CN 200920271635XU CN 200920271635 U CN200920271635 U CN 200920271635U CN 201523324 U CN201523324 U CN 201523324U
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- 238000009413 insulation Methods 0.000 claims abstract description 6
- 238000002955 isolation Methods 0.000 claims description 21
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 238000004382 potting Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 230000008878 coupling Effects 0.000 abstract 1
- 238000010168 coupling process Methods 0.000 abstract 1
- 238000005859 coupling reaction Methods 0.000 abstract 1
- 230000005611 electricity Effects 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 abstract 1
- 238000004804 winding Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000003442 weekly effect Effects 0.000 description 1
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Abstract
The utility model provides a super-strong insulating RS485 power supply circuit for an electric energy meter, which comprises a clamp protecting circuit, a switch oscillating circuit, a pulse transformer, a feedback circuit and an n-shaped filter circuit, wherein input voltage passes through the clamp circuit on the front stage, input low voltage direct current voltage drives the pulse transformer to work through dutyfactor modulation of pulse width through the switch oscillating circuit, the feedback circuit feeds back to a switch chip of the switch oscillating circuit through optical coupling thereof according to the load changes of the output voltage and the changes of the input voltage, and thereby modulating the dutyfactor, and the output voltage of the pulse transformer is adjusted at any time to be stabilized in the preset value. The super-strong insulating RS485 power supply circuit is simple, and has the greatest characteristic that the insulation intensity with the logic and strong electricity part of the electric energy meter is strong, can achieve the insulation intensity of 8KV, has high switch frequency and low work input voltage, and can work with 3VDC.
Description
Technical field
The utility model relates to a kind of power circuit and pulse transformer thereof that is used for electric energy meter RS485 circuit.
Background technology
We know that electric energy meter all has the RS485 telecommunication circuit, and the RS485 order wire of electric energy meter is directly maked somebody a mere figurehead aloft and length very often, so Chang distance often is easy to be subjected to extraneous interference, might cause the main power source irregular working once the RS485 circuit damages, thus the influence metering.And the power circuit of RS485 telecommunication circuit is related to stable, the reliability service of whole RS485.The power supply major part of using in most at present communication RS485 circuit is that the linear transformer step-down is given the RS485 circuit supply through 7805 voltage stabilizings again.The characteristics of this circuit are that the input power range is narrow, efficient is low, volume is big and isolation strength is not high, the highest have only 4KVAC, because it is to isolate by the winding of linear transformer to reach corresponding insulation request fully, because the former limit winding of linear transformer has several thousand circles up to ten thousand, if will guarantee that also the isolation strength of the former limit of transformer and secondary (RS485) winding is very high as 6KV or 8KV, what the skeleton of transformer can be done very so is big, and this is unpractical in the electric energy meter the inside.The RS485 power supply of electric energy meter and electric energy meter logic and strong power part isolation at present is the highest can only accomplish 4KV.Therefore how to guarantee that the little and isolation strength of volume can accomplish that again the superpower isolation RS 485 power supply of 8KV is exactly a new difficult problem.
The utility model content
The purpose of this utility model is to provide a kind of can reduce pulse transformer volume in the power supply, significantly improves isolation strength, strengthens the antijamming capability of power supply, ensures the isolation RS 485 power supply circuit that is used for electric energy meter and the pulse transformer thereof of electric energy meter reliably working.
This isolation RS 485 power supply circuit that is used for electric energy meter that the utility model provides; comprise clamping protective circuit; the switch oscillating circuit; pulse transformer; feedback circuit; ∏ type filter circuit; input voltage is at prime process clamp circuit; through the switch oscillating circuit low-voltage dc voltage of input is worked through the duty ratio modulation pulse transformer of pulsewidth again; thereby feedback circuit feeds back to the switch chip modulation duty cycle of switch oscillating circuit according to the variation of the load variations of output voltage and input voltage by its optocoupler, and the output voltage of regulating impulse transformer is stabilized in predetermined value always at any time.
The switch chip of described switch oscillating circuit adopts the LM2733 chip.
The superpower isolation optocoupler TLP621 that the optocoupler of described feedback circuit selects for use 10000VDC to isolate.
The pulse transformer that is used for foregoing circuit that the utility model provides adopts compact core and the skeleton of EFD-15, the three layer insulation wire coiling of the line of former limit and secondary, and the isolation strength of each layer insulated wire is 3KV.
In order to strengthen the creepage distance between former limit of described transformer and the secondary, between former limit and secondary coiling, above skeleton, increase baffle plate and potting fully.
The utility model circuit is simple, and its maximum characteristics are very strong with electric energy meter logic and strong power part isolation strength, the isolation strength that can accomplish 8KV, and the switching frequency height, the work input voltage is very low, and 3VDC just can work.Because input service voltage is low and switching frequency is high, can make the former limit of pulse transformer and secondary winding have only several circles, thereby can make the skeleton of this pulse transformer and magnetic core select very for a short time.The isolation strength that has reached power supply thus is good, and the pulse transformer volume is little, and the antijamming capability of power supply is strong, ensures the purpose of electric energy meter reliably working.
Description of drawings
Fig. 1 is the circuit structure block diagram of the utility model patent;
Fig. 2 is the circuit diagram of a kind of execution mode of the utility model patent;
Fig. 3 is the structural representation of the utility model pulse transformer.
Embodiment
Input voltage, is worked the low-voltage dc voltage of input through the switch oscillating circuit through clamp circuit in prime again through the duty ratio modulation pulse transformer of pulsewidth as can be seen from Figure 1.And thereby feedback circuit feeds back to switch control chip modulation duty cycle according to the load variations of output voltage and the variation of input voltage by optocoupler, and the output voltage of regulating impulse transformer is stabilized in predetermined value 5V always at any time.High-frequency noise on the ∏ type filtering filtering DC power supply.
Fig. 2 has reacted an embodiment of the utility model patent:
As can be seen from Figure 2, switch oscillating circuit of the present utility model is made up of capacitor C 8, C1 and DC/DC switch chip, and DC input voitage is input to switch chip through capacitor C 8, C1 filtering.This switch chip U1 is the LM2733 chip of the National Semiconductor that selects for use.The maximum characteristics of this chip are that input voltage is low from 3VDC-14VDC, can both operate as normal and switching frequency reached 600Khz.Along with the variation of input voltage and the variation of load, the switch chip duty ratio can be regulated automatically, guarantees that output voltage is surely at a steady state value.This chip also has cycle-by-cycle (phase weekly) overcurrent protection function, and when accidental short circuit appearred in output loading, chip logic circuit can be closed the duty cycle adjustment device automatically, carried out the conversion work of cycle-by-cycle Cycle by Cycle.After short trouble was removed, PWM can normally carry out duty cycle adjustment again again.Resistance R 2 and capacitor C 2, D1 has formed clamp circuit.Suppress the safe voltage that voltage that overvoltage spike and pulse guarantee to be input to switch chip LM2733 is no more than it.Resistance R 6-R8, pressurizer N2, optocoupler N1 and resistance R 3 have been formed feedback circuit, thereby feed back to the switch chip modulation duty cycle according to the load variations of output voltage and the variation of input voltage by optocoupler, and the output voltage of regulating impulse transformer is stabilized in 5V always at any time.Capacitor C 5, C6 and inductance L 1 have been formed switching noise and the High-frequency Interference on the ∏ type filter circuit filtering dc output power.
Pulse transformer of the present utility model as can be seen from Figure 3 adopts magnetic core and the skeleton of EFD-15, length * wide * height has only 18 * 18 * 11, increase middle baffle plate I at skeleton in former limit and secondary winding department, the thickness of skeleton two side guard II is 1.6mm, and middle baffle plate I thickness is 0.8mm.Can further strengthen the creepage distance between former limit and the secondary thus.Three layer insulation wire is selected in coiling for use, and the dielectric strength of each layer is 3KVAC, and the whole potting of transformer has just guaranteed fully reliably that the isolation strength of former limit and secondary can reach 8KV.
Maximum characteristics of the present utility model are that circuit is simple, can make the pulse transformer volume little, and the number of turn of former secondary only has several circles, and the work input voltage is very low, and 3VDC just can work, and the isolation strength of power supply reaches the superpower isolation of 8KV.
Claims (6)
1. isolation RS 485 power supply circuit that is used for electric energy meter; it is characterized in that this comprises clamping protective circuit; the switch oscillating circuit; pulse transformer; feedback circuit; ∏ type filter circuit; input voltage is at prime process clamp circuit; through the switch oscillating circuit low-voltage dc voltage of input is worked through the duty ratio modulation pulse transformer of pulsewidth again; thereby feedback circuit feeds back to the switch chip modulation duty cycle of switch oscillating circuit according to the variation of the load variations of output voltage and input voltage by its optocoupler, and the output voltage of regulating impulse transformer is stabilized in predetermined value always at any time.
2. the isolation RS 485 power supply circuit that is used for electric energy meter according to claim 1 is characterized in that the switch chip of described switch oscillating circuit adopts the LM2733 chip.
3. according to claim 1 or 2 or the described isolation RS 485 power supply circuit that is used for electric energy meter, it is characterized in that the superpower isolation optocoupler TLP621 that the optocoupler of described feedback circuit selects for use 10000VDC to isolate.
4. a pulse transformer that is used for one of claim 1-3 described circuit is characterized in that this pulse transformer adopts the compact core and the skeleton of EFD-15 shape, the three layer insulation wire coiling of the line of former limit and secondary.
5. pulse transformer according to claim 4 is characterized in that increasing middle baffle plate (I) and potting fully on skeleton between former limit and secondary coiling.
6. pulse transformer according to claim 5, the thickness that it is characterized in that described skeleton two side guards is 1.6mm, described middle baffle plate (I) thickness is 0.8mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920271635XU CN201523324U (en) | 2009-11-13 | 2009-11-13 | Insulating RS485 power supply circuit for electric energy meter and pulse transformer thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920271635XU CN201523324U (en) | 2009-11-13 | 2009-11-13 | Insulating RS485 power supply circuit for electric energy meter and pulse transformer thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201523324U true CN201523324U (en) | 2010-07-07 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200920271635XU Expired - Lifetime CN201523324U (en) | 2009-11-13 | 2009-11-13 | Insulating RS485 power supply circuit for electric energy meter and pulse transformer thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201523324U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108737237A (en) * | 2018-06-27 | 2018-11-02 | 浙江禾川科技股份有限公司 | A kind of RS485 bus communication circuits based on transformer |
-
2009
- 2009-11-13 CN CN200920271635XU patent/CN201523324U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108737237A (en) * | 2018-06-27 | 2018-11-02 | 浙江禾川科技股份有限公司 | A kind of RS485 bus communication circuits based on transformer |
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Legal Events
| 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: 20100707 |