CN110048622A - A kind of power circuit and three-phase kilowatt-hour meter system for electric energy meter - Google Patents

Abstract

The invention belongs to the technical field of electronic circuits, and provides a power supply circuit for an electric energy meter and a three-phase electric meter system, including a protection module, a rectifier module, a filter module, an electrolysis module, a switch module, a feedback module and an output module. After overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, and power storage are performed on the power signal output by the three-phase power supply, the switch module conducts conduction according to the power signal stored in the power, and outputs the drive signal and the power supply signal. After voltage conversion, the final output module combines the feedback signal provided by the feedback module to perform ripple processing on the power supply signal after voltage conversion, and then outputs the optimized electrical signal to drive the electric energy meter. Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter, which greatly improves the performance of the power meter. Efficiency and stability.

Description

A power supply circuit for electric energy meter and three-phase electric meter system

technical field

The invention belongs to the technical field of electronic circuits, and in particular relates to a power supply circuit for an electric energy meter and a three-phase electric meter system.

Background technique

At present, the power supply of domestic electric energy meters is still dominated by traditional power frequency transformers, while some foreign products have gradually used switching power supplies. The main reason is that after the function of the electric energy meter is strengthened, the power supply requirements increase, and the power frequency transformer is difficult to be competent. Switching power supplies are different from other devices in electric energy meters. Large-scale and standardized production may improve quality, reduce production costs, and optimize production processes. The existing power supply technology for electric energy meters is not yet mature, with low efficiency and poor stability.

Therefore, the existing power supply technology for electric energy meters has the problems of low efficiency and poor stability due to lack of protection function and burst mode to cope with light load efficiency.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a power supply circuit for an electric energy meter and a three-phase electric meter system, aiming at solving the existing power supply technology for electric energy meters. This leads to problems of low efficiency and poor stability.

A first aspect of the present invention provides a power supply circuit for an electric energy meter, the power supply circuit comprising:

A protection module connected to a three-phase power supply for overvoltage protection and surge current suppression for the power signal output by the three-phase power supply;

A rectifier module connected to the protection module for full-wave rectification of the power supply signal after overvoltage protection and suppression of surge current;

A filter module connected to the rectifier module for common-mode filtering of the full-wave rectified power supply signal;

An electrolytic module that is connected to the filtering module and used to store the power of the power signal after common mode filtering;

connected with the electrolysis module, and used for conducting conduction according to the power supply signal stored in electric power, and outputting a driving signal and a switch module for voltage conversion of the power supply signal;

a feedback module connected to the switch module for outputting a feedback signal according to the drive signal; and

The output module is connected to the switch module and the feedback module, and is used for combining the feedback signal to output the optimized electric signal to drive the output module of the electric energy meter after performing ripple processing on the voltage-converted power supply signal.

A second aspect of the present invention provides a three-phase electric meter system, including an electric energy meter and a three-phase power supply for providing a power signal, and the three-phase electric meter system further includes the above-mentioned power supply circuit.

The present invention provides a power supply circuit for an electric energy meter and a three-phase electric meter system, including a protection module, a rectifier module, a filter module, an electrolysis module, a switch module, a feedback module and an output module. After the power signal is subjected to overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, and power storage, the switch module conducts conduction according to the power signal stored in power, and outputs the drive signal and voltage conversion of the power signal, and finally outputs Combined with the feedback signal provided by the feedback module, the module performs ripple processing on the voltage-converted power supply signal, and outputs an optimized electrical signal to drive the electric energy meter. Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, voltage conversion, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter. The efficiency is greatly improved, and the stability is strong, which solves the problems of low efficiency and poor stability due to the lack of protection function and the burst mode of dealing with light load efficiency in the existing power supply technology for electric energy meters.

Description of drawings

FIG. 1 is a schematic structural diagram of a module of a power supply circuit for an electric energy meter according to an embodiment of the present invention.

FIG. 2 is a circuit example diagram of a power supply circuit for an electric energy meter provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

The above-mentioned power supply circuit for an electric energy meter and a three-phase electric meter system include a protection module, a rectifier module, a filter module, an electrolysis module, a switch module, a feedback module and an output module. After over-voltage protection, surge current suppression, full-wave rectification, common-mode filtering and power storage, the switch module conducts conduction according to the power signal stored in power, outputs the drive signal and performs voltage conversion on the power signal, and finally the output module combines The feedback signal provided by the feedback module, after the ripple processing of the power supply signal after voltage conversion, outputs the optimized electric signal to drive the electric energy meter. Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, voltage conversion, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter. The efficiency is greatly improved, and its stability is strong.

FIG. 1 shows a module structure of a power supply circuit for an electric energy meter provided by an embodiment of the present invention. For convenience of description, only the parts related to this embodiment are shown, and the details are as follows:

In the above-mentioned power supply circuit for an electric energy meter, the power supply circuit includes a protection module 102 , a rectifier module 103 , a filter module 104 , an electrolysis module 105 , a switch module 106 , a feedback module 108 and an output module 107 .

The protection module 102 is connected to the three-phase power supply 101 , and is used for overvoltage protection and surge current suppression for the power signal output by the three-phase power supply 101 .

The rectification module 103 is connected to the protection module 102, and is used for performing full-wave rectification on the power signal after overvoltage protection and suppression of surge current.

The filtering module 104 is connected to the rectifying module 103, and is used for performing common mode filtering on the full-wave rectified power supply signal.

The electrolysis module 105 is connected to the filter module 104, and is used to store the power of the power signal after the common mode filter.

The switch module 106 is connected to the electrolysis module 105, and is used for conducting conduction according to the power supply signal stored in the electric quantity, and outputting the driving signal and performing voltage conversion on the power supply signal.

The feedback module 108 is connected to the switch module 106 for outputting a feedback signal according to the driving signal.

The output module 107 is connected to the switch module 106 and the feedback module 108 , and is used for combining the feedback signal to output the optimized electric signal to drive the electric energy meter 109 after ripple processing on the voltage-converted power supply signal.

As an embodiment of the present invention, after the above-mentioned power supply circuit sequentially performs overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, and power storage on the power signal output by the three-phase power supply 101, the switch module 106 stores the power according to the power The power supply signal is turned on, and the drive signal is output and the power signal is voltage transformed. Finally, the output module combines the feedback signal provided by the feedback module to ripple the power signal after the voltage transformation, and outputs the optimized electrical signal to drive the electrical energy. Table 109. Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, voltage conversion, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter. The efficiency is greatly improved, and its stability is strong.

FIG. 2 shows an example circuit of a power supply circuit for an electric energy meter provided by an embodiment of the present invention. For the convenience of description, only the parts related to this embodiment are shown, and the details are as follows:

As an embodiment of the present invention, the protection module 102 includes a first varistor RV1 , a second varistor RV2 , a third varistor RV3 , a fifteenth resistor R315 , a sixteenth resistor R316 and a seventeenth resistor R317 ;

The first end of the first varistor RV1 and the first end of the fifteenth resistor R315 are connected to the A-phase end of the three-phase power supply 101, and the first end of the second varistor RV2 and the first end of the sixteenth resistor R316 Connect the B-phase terminal of the three-phase power supply 101, the first terminal of the third varistor RV3 and the first terminal of the seventeenth resistor R317 are connected to the C-phase terminal of the three-phase power supply 101, and the second terminal of the first varistor RV1 The second end of the second varistor RV2 and the second end of the third varistor RV3 are connected to the neutral line of the three-phase power supply 101, the second end of the fifteenth resistor R315 and the second end of the sixteenth resistor R316 And the second terminal of the seventeenth resistor R317 is connected to the rectifier module 103 .

As an embodiment of the present invention, the rectifier module 103 includes a first diode D201 , a second diode D202 , a third diode D203 , a seventh diode D207 , an eighth diode D208 , and a ninth second diode D207 . The pole tube D209, the tenth diode D210 and the eleventh diode D211;

The cathode of the eighth diode D208 is connected to the anode of the first diode D201, the cathode of the ninth diode D209 is connected to the anode of the second diode D202, and the cathode of the tenth diode D210 is connected to the third diode The anode of D203, the cathode of the eleventh diode D211 is connected to the anode of the seventh diode D7, the anode of the eighth diode D208, the anode of the ninth diode D209, the anode of the tenth diode D210 and The anode of the eleventh diode D211 is connected to the filter module 104, the cathode of the first diode D201, the cathode of the second diode D202, the cathode of the third diode D203, and the cathode of the seventh diode D207 are connected to Filtering module 104 .

As an embodiment of the present invention, the filter module 104 includes a first inductor L1, a second inductor L2, a third inductor L3, a seventh common-mode inductor L7, and a fourth capacitor C204;

The first end of the fourth capacitor C204 is connected to the first end of the first inductor L1, the second end of the first inductor L1 is connected to the first end of the third inductor L3, and the second end of the third inductor L3 is connected to the seventh common mode inductor The first end of the first coil of L7, the second end of the fourth capacitor C204 is connected to the first end of the second inductor L2, and the second end of the second inductor L2 is connected to the first end of the second coil of the seventh common mode inductor L7 The second end of the first coil and the second end of the second coil of the seventh common mode inductor L7 are both connected to the electrolysis module 105 .

As an embodiment of the present invention, the electrolytic module 105 includes a fifth electrolytic capacitor C205, a sixth electrolytic capacitor C206, a twenty-ninth resistor R29, a thirtieth resistor R30, a thirty-first resistor R31, and a thirty-second resistor R32 ;

The first end of the fifth electrolytic capacitor C205 is connected to the first end of the twenty-ninth resistor R29, the second end of the twenty-ninth resistor R29 is connected to the first end of the thirtieth resistor R30, and the second end of the fifth electrolytic capacitor C205 is connected to the first end of the thirtieth resistor R30. terminal, the first terminal of the sixth electrolytic capacitor C206, the second terminal of the thirtieth resistor R30 and the first terminal of the thirty-first resistor R31 are connected together, and the second terminal of the thirty-first resistor R31 is connected to the thirty-second The first end of the resistor R32 and the second end of the sixth electrolytic capacitor C206 are connected to the second end of the thirty-second resistor R32.

As an embodiment of the present invention, the switch module 106 includes a twentieth resistor R320, a twenty-first resistor R321, a twenty-second resistor R322, a twenty-third resistor R323, a twenty-fourth resistor R324, and a twenty-fifth resistor R322. Resistor R325, TVS8, first resistor R301, second resistor R302, third resistor R303, fourth resistor R304, fifth resistor R305, sixth resistor R306, eighth capacitor C208, ninth capacitor C209, Twenty-one capacitors C221, fourth diode C204, field effect transistor Q25, eighteenth diode D18, switch chip U101, first capacitor C111, twenty-second capacitor C222, seventh capacitor C207 and transformer T1;

The first terminal of the twentieth resistor R320 is connected to the electrolysis module 105, the second terminal of the twentieth resistor R320 is connected to the first terminal of the twenty-first resistor R321, and the second terminal of the twenty-first resistor R321 is connected to the twenty-second resistor R321. The first end of the resistor R322, the second end of the twenty-second resistor R322 are connected to the first end of the twenty-third resistor R323, the second end of the twenty-third resistor R323 and the first end of the twenty-fourth resistor R324 And the first end of the twenty-fifth resistor R325 is connected in common, the second end of the twenty-fourth resistor R324 is connected with the second end of the twenty-fifth resistor R325 and the first end of the transient suppression diode TVS8, the first The first end of the resistor R301, the first end of the second resistor R302, the first end of the twenty-first capacitor C221, the first end of the eighth capacitor C208, the first end of the fifth resistor R305, and the first end of the ninth capacitor C209 The first end is connected to the input end of the primary coil of the transformer T1, the second end of the first resistor R301 is connected to the first end of the third resistor R303, the second end of the second resistor R302 is connected to the first end of the fourth resistor R304, and the second end of the second resistor R302 is connected to the first end of the fourth resistor R304. The second end of the third resistor R303, the second end of the fourth resistor R304, the second end of the twenty-first capacitor C221 and the cathode of the fourth diode C204 are connected in common, and the second end of the eighth capacitor C208 is connected to the ninth The second end of the capacitor C209 is grounded, the anode of the fourth diode C204 and the source of the FET Q25 are connected to the output end of the primary coil of the transformer T1, the second end of the fifth resistor R305 is connected to the first end of the sixth resistor R306 terminal, the secondary coil of the transformer T1 is connected to the output module 107, the second terminal of the sixth resistor R306 is connected to the first terminal of the first capacitor C111, the drain of the switch chip U101 and the anode of the eighteenth diode D18 and the field effect The drain of the transistor Q25 is connected in common, the cathode of the eighteenth diode D18 is connected to the gate of the FET Q25, the source of the switch chip U101 is connected to the second terminal of the transient suppression diode TVS8, and the bypass terminal of the switch chip U101 Connect the first end of the twenty-second capacitor C222 and the first end of the seventh capacitor C207, the enabling end of the switch chip U101 is connected to the feedback module 108, the second end of the first capacitor C111 and the second end of the twenty-second capacitor C222. The two terminals and the second terminal of the seventh capacitor C207 are connected in common.

As an embodiment of the present invention, the output module 107 includes a seventh resistor R307, an eighth resistor R308, a fifth diode D205, a sixth diode D206, an eleventh capacitor C211, a twelfth capacitor C212, and a tenth Three capacitors C213, fourteenth capacitor C214, fifteenth capacitor C215, sixteenth capacitor C216, eighteenth capacitor C218, seventy-ninth capacitor C79 and fourth inductor L4;

The first end of the seventh resistor R307 is connected to the anode of the fifth diode D205, the second end of the seventh resistor R307 is connected to the first end of the eleventh capacitor C211, the second end of the eleventh capacitor C211, the second end of the fifth The cathode of the pole tube D205, the first end of the seventy-ninth capacitor C79 and the first end of the fourteenth capacitor C214 are connected in common and connected to the electric energy meter 109, and the second end of the seventy-ninth capacitor C79 is connected to the fourteenth capacitor The second terminal of C214 is grounded, the first terminal of the eighth resistor R308 is connected to the anode of the sixth diode D206, the second terminal of the eighth resistor R308 is connected to the first terminal of the twelfth capacitor C212, and the The second end, the cathode of the sixth diode D206, the first end of the thirteenth capacitor C213, the first end of the fifteenth capacitor C215, and the first end of the fourth inductor L4 are connected in common. The two terminals are connected to the first terminal of the sixteenth capacitor C216 and the first terminal of the eighteenth capacitor C218 and are connected to the electric energy meter 109. The second terminal of the sixteenth capacitor C216 is connected to the second terminal of the eighteenth capacitor C218. ground.

As an embodiment of the present invention, the feedback module 108 includes a photocoupler U25, a ninth resistor R309, a tenth resistor R310, an eleventh resistor R311, a twelfth resistor R312, a thirteenth resistor R313, and a fourteenth resistor R314 , the nineteenth capacitor C219, the twentieth capacitor C220 and the voltage regulator U26;

The light receiver of the photocoupler U25 is connected to the switch module 106, the input end of the light source of the photocoupler U25 is connected to the first end of the fourteenth resistor R314, and the second end of the fourteenth resistor R314 is connected to the third end of the thirteenth resistor R313. One end, the second end of the thirteenth resistor R313 is connected to the output end of the light-emitting source of the photocoupler U25, the first end of the nineteenth capacitor C219 and the first end of the twentieth capacitor C220 and the output of the voltage regulator U26 The terminals are connected together, the second terminal of the nineteenth capacitor C219 is connected to the first terminal of the twelfth resistor R312, the second terminal of the twelfth resistor R312, the second terminal of the twentieth capacitor C220, and the first terminal of the ninth resistor R309 One end, the first end of the tenth resistor R310 and the first end of the eleventh resistor R311 are connected together, the second end of the ninth resistor R309 is connected to the output module 107, the second end of the tenth resistor R310 is connected to the eleventh resistor The second terminal of R311 and the input terminal of the voltage regulator U26 are connected in common.

The present invention also provides a three-phase electric meter system, including an electric energy meter and a three-phase power supply for providing a power signal, and the three-phase electric meter system further includes the above-mentioned power supply circuit.

The power supply system of the above-mentioned electric energy meter 109 selects a switching power supply. Considering the low-power switching power supply with a conventional input voltage of 230V±15%, comprehensive efficiency and cost, a flyback topology power supply is selected.

This power supply system selects the switch chip of model TNY285. In addition to integrating a current module controller with an operating frequency of 132KHz, it also integrates a 725V MOSFET, with an on-resistance of 19Ω and a DIP7 package. The chip also integrates a 725V high voltage start-up unit. When the ambient temperature is 50 degrees and the conventional wide voltage input (85Vac-265Vac), the maximum input power can reach 11.5W. At the same time, the switch chip U101 also has protection functions such as overcurrent, overvoltage, input undervoltage, and overtemperature, and a burst mode to improve light-load efficiency.

The working principle of the above-mentioned power supply circuit for an electric energy meter and a three-phase electric meter system will be described below with reference to FIGS. 1-2 :

First, the input voltage goes through the full-wave rectification and common-mode filter of the previous stage (through the fourth capacitor C204 and the seventh common-mode inductor L7); the varistor RV1, RV2, RV3 form an overvoltage protection circuit; the power resistors R315, R316 , R317 is used to suppress surge current. The position of the filter inductor is placed after the rectifier bridge to save costs. At the same time, considering the input phase loss, that is, as long as any two wires exist, no matter whether the live wire is neutral or the live wire, the system can still work normally, using full-wave rectification. After rectification, since the maximum peak voltage can reach 780V, two 450V electrolytic capacitors (that is, the fifth electrolytic capacitor C205 and the sixth electrolytic capacitor C206) are used in series. At the same time, considering the voltage balance, resistors R29~R32 are used in parallel with the capacitors. sides.

Secondly, the switch circuit of the primary side consists of transformer T1, clamp circuit, switch tube and switch chip U101, transient suppression diode TVS8, Zener diode and so on. When starting, the current flows through the Zener diode D18 through R320-R323 and enters the high-voltage start-up unit connected to the drain of the switch chip U101. The high voltage startup unit inside the switch chip U101 is 725V. Due to the existence of the external transient suppression diode TVS8, the ultra-high voltage will be clamped to a specific voltage to protect the switch chip U101. However, when the switch chip U101 is turned on, the source of the external MOSFET is pulled to the ground, so that the Zener diode D18 forms a reverse bias, so that the external MOSFET is turned on; when the switch chip U101 is turned off, the inductor current will first affect the MOSFET inside the switch chip U101. The drain-source capacitance of the external MOSFET is charged until the Vds voltage reaches the clamping voltage of the external TVS8 diode, and the current begins to discharge the gate-source capacitance of the external MOSFET until the forward voltage of the Zener diode between GS exceeds 0.7V, the external MOSFET is turned off, and the current will flow to the external transient suppression diode TVS8 or resistors R320~R323 through the voltage regulator diode D18. Depending on the impedance of the two loops, since the Vgs of the external MOSFET is already close to zero, the MOSFET will be completely turned off; for the input exceeding the rated voltage of the external transient suppression diode TVS8, the voltage stress of R320~R323 is the external transient voltage. The clamping voltage value of the state suppression diode TVS8. For example, if a 550V transient suppression diode TVS8 and a 600V external MOSFET are used, the voltage withstand capability of the flyback is: 550V+600V=1150V. Considering the bad situation, it can be roughly estimated that the time from the internal MOSFET to the turn-off of the external MOSFET is the time flowing through the external TVS8 diode, and the average current flowing through the TVS8 is easily obtained from the peak current at the maximum load. Therefore, the TVS8 loss is the product of the average current and the clamping voltage. The output module 107 is composed of a Schottky diode, an absorption circuit and a filter. For ripple requirements, a secondary filter is used. Among them, output 2 is the main 12V, the other output 1 is the auxiliary 12V, and the ground of the two outputs is isolated.

Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, voltage conversion, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter. The efficiency is greatly improved, and its stability is strong.

To sum up, a power supply circuit for an electric energy meter and a three-phase electric meter system provided by the embodiments of the present invention include a protection module, a rectifier module, a filter module, an electrolysis module, a switch module, a feedback module, and an output module. After the power signal output by the three-phase power supply is subjected to overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, and power storage, the switch module conducts conduction according to the power signal stored in the power, and outputs the drive signal and the power signal. For voltage conversion, the final output module combines the feedback signal provided by the feedback module to perform ripple processing on the power supply signal after voltage conversion, and then outputs the optimized electrical signal to drive the electric energy meter. Therefore, after a series of processing actions such as overvoltage protection, surge current suppression, full-wave rectification, common-mode filtering, voltage conversion, and ripple processing are performed on the power signal output by the three-phase power supply, a stable signal is output to drive the electric energy meter. The efficiency is greatly improved, and the stability is strong, which solves the problems of low efficiency and poor stability due to the lack of protection function and the burst mode of dealing with light load efficiency in the existing power supply technology for electric energy meters.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (9)

1. a kind of power circuit for electric energy meter, which is characterized in that the power circuit includes:

It is connect with three phase mains, the power supply signal for exporting to the three phase mains carries out overvoltage protection and inhibits surge current Protective module；

It is connect with the protective module, it is whole for carrying out all-wave to the power supply signal after overvoltage protection and inhibition surge current The rectification module of stream；

It is connect with the rectification module, for carrying out the filter module of common mode filtering to the power supply signal after full-wave rectification；

It is connect with the filter module, for carrying out the electrolytic module of electricity storage to the power supply signal after common mode filtering；

It is connect with the electrolytic module, the power supply signal for being stored according to electricity is connected, and output drive signal And the switch module of voltage transformation is carried out to the power supply signal；

It is connect with the switch module, for exporting the feedback module of feedback signal according to the driving signal；And

It connect, is used in conjunction with the feedback signal, described in after voltage transformation with the switch module and the feedback module After power supply signal carries out ripple processing, output optimizes electric signal to drive the output module of electric energy meter.

2. power circuit as described in claim 1, which is characterized in that the protective module includes:

First varistor, the second varistor, third varistor, the 15th resistance, the 16th resistance and the 17th electricity Resistance；

The first end of first varistor and the A phase of the first termination three phase mains of the 15th resistance are held, institute The B phase for stating the first end of the second varistor and the first termination three phase mains of the 16th resistance is held, the third The first end of varistor and the C phase of the first termination three phase mains of the 17th resistance are held, the first pressure-sensitive electricity The second termination three-phase electricity of the second end and the third varistor of the second end of resistance and second varistor The of the zero curve in source, the second end of the second end of the 15th resistance and the 16th resistance and the 17th resistance The two termination rectification modules.

3. power circuit as described in claim 1, which is characterized in that the rectification module includes:

First diode, the second diode, third diode, the 7th diode, the 8th diode, the 9th diode, the 12nd Pole pipe and the 11st diode；

The cathode of 8th diode connects the anode of the first diode, and the cathode of the 9th diode connects described second The anode of diode, the cathode of the tenth diode connect the anode of the third diode, the yin of the 11st diode Pole connects the anode of the 7th diode, the anode of the 8th diode, the anode of the 9th diode, the described 12nd The anode of the anode of pole pipe and the 11st diode connects the filter module, the cathode of the first diode, described The cathode of second diode, the cathode of the third diode, the 7th diode cathode connect the filter module.

4. power circuit as described in claim 1, which is characterized in that the filter module includes:

First inductance, the second inductance, third inductance, the 7th common mode inductance and the 4th capacitor；

The first end of first termination first inductance of the 4th capacitor, the second termination third of first inductance The first end of inductance, the first end of the first coil of the second termination the 7th common mode inductance of the third inductance, described the The first end of second termination second inductance of four capacitors, the second termination the 7th common mode inductance of second inductance The first end of second coil, the second end of first coil and the second end of the second coil of the 7th common mode inductance connect described Electrolytic module.

5. power circuit as described in claim 1, which is characterized in that the electrolytic module includes:

5th electrolytic capacitor, the 6th electrolytic capacitor, the 29th resistance, the 30th resistance, the 31st resistance and the 30th Two resistance；

The first end of first termination the 29th resistance of the 5th electrolytic capacitor, the second of the 29th resistance Terminate the first end of the 30th resistance, the second end of the 5th electrolytic capacitor, the first end of the 6th electrolytic capacitor, The second end of 30th resistance and the first end of the 31st resistance connect altogether, and the second of the 31st resistance The first end of the 32nd resistance is terminated, the second of the 6th electrolytic capacitor terminates the second of the 32nd resistance End.

6. power circuit as described in claim 1, which is characterized in that the switch module includes:

20th resistance, the 21st resistance, the 22nd resistance, the 23rd resistance, the 24th resistance, the 25th electricity Resistance, Transient Suppression Diode, first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 8th Capacitor, the 9th capacitor, the 21st capacitor, the 4th diode, field-effect tube, the 18th diode, switch chip, the first electricity Appearance, the 22nd capacitor, the 7th capacitor and transformer；

The first termination electrolytic module of the 20th resistance, the second termination the described 21st of the 20th resistance The first end of resistance, the first end of the second termination the 22nd resistance of the 21st resistance, the described 22nd The first end of second termination the 23rd resistance of resistance, the second end and the described 24th of the 23rd resistance The first end of resistance and the first end of the 25th resistance connect altogether, the second end of the 24th resistance and described the The second end of 25 resistance and the first end of the Transient Suppression Diode connect altogether, the first end of the first resistor, institute State the first end of second resistance, the first end of the 21st capacitor, the first end of the 8th capacitor, the 5th resistance First end and the 9th capacitor the first termination transformer primary coil input terminal, the first resistor The first end of the second termination 3rd resistor, the first end of the second termination the 4th resistance of the second resistance are described The second end of 3rd resistor, the second end of the 4th resistance, the second end and the described 4th 2 of the 21st capacitor The cathode of pole pipe connects altogether, and the second end of the 8th capacitor and the second end of the 9th capacitor are grounded, the 4th diode Anode and the field-effect tube source electrode connect the transformer primary coil output end, the second end of the 5th resistance Connecing the first end of the 6th resistance, the secondary coil of the transformer connects the output module, and the second of the 6th resistance Terminate the first end of the first capacitor, anode and the field of the drain electrode of the switch chip with the 18th diode The drain electrode of effect pipe connects altogether, and the cathode of the 18th diode connects the grid of the field-effect tube, the source of the switch chip Pole connects the second end of the Transient Suppression Diode, and the bypass of the switch chip terminates the first end of the 22nd capacitor And the first end of the 7th capacitor, the enabled termination feedback module of the switch chip, the of the first capacitor Two ends connect altogether with the second end of the 22nd capacitor and the second end of the 7th capacitor.

7. power circuit as described in claim 1, which is characterized in that the output module includes:

7th resistance, the 8th resistance, the 5th diode, the 6th diode, the 11st capacitor, the 12nd capacitor, the 13rd capacitor, 14th capacitor, the 15th capacitor, the 16th capacitor, the 18th capacitor, the 79th capacitor and the 4th inductance；

The anode of first termination the 5th diode of the 7th resistance, the second termination the described tenth of the 7th resistance The first end of one capacitor, the second end of the 11st capacitor, the cathode of the 5th diode, the 79th capacitor First end and the first end of the 14th capacitor connect altogether and connect with the electric energy meter, and the second of the 79th capacitor End and the second end of the 14th capacitor are grounded, the anode of the first termination the 6th diode of the 8th resistance, institute State the first end of the second termination the 12nd capacitor of the 8th resistance, the second end of the 12nd capacitor, the described 6th 2 The cathode of pole pipe, the first end of the 13rd capacitor, the first end of the 15th capacitor and the 4th inductance One end connects altogether, and the first of the second end of the 4th inductance and the first end of the 16th capacitor and the 18th capacitor End connects altogether and connect with the electric energy meter, and the second end of the 16th capacitor and the second end of the 18th capacitor are grounded.

8. power circuit as described in claim 1, which is characterized in that the feedback module includes:

Photoelectrical coupler, the 9th resistance, the tenth resistance, eleventh resistor, twelfth resistor, thirteenth resistor, the 14th resistance, 19th capacitor, the 20th capacitor and voltage-stablizer；

The light-receiving device of the photoelectrical coupler connects the switch module, described in the input termination of the light emitting source of the photoelectrical coupler The first end of 14th resistance, the first end of the second termination thirteenth resistor of the 14th resistance, the described 13rd The output end of the light emitting source of the second termination photoelectrical coupler of resistance, the first end and described second of the 19th capacitor The output end of the first end of ten capacitors and the voltage-stablizer connects altogether, the second termination of the 19th capacitor the 12nd electricity The first end of resistance, the second end of the twelfth resistor, the second end of the 20th capacitor, the 9th resistance first End, the first end of the tenth resistance and the first end of the eleventh resistor connect altogether, the second termination of the 9th resistance The output module, the second end and the second end of the eleventh resistor and the input of the voltage-stablizer of the tenth resistance End connects altogether.

9. a kind of three-phase kilowatt-hour meter system, including electric energy meter and for providing the three phase mains of power supply signal, which is characterized in that described Three-phase kilowatt-hour meter system further includes such as the described in any item power circuits of claim 1-8.