Rectifying and filtering circuit with double high-voltage clamping protection for electric energy meter

Abstract

The utility model relates to a dual high-voltage clamping protection rectification filter circuit for an electric energy meter. The dual high-voltage clamping protection rectification filter circuit comprises three LC filter circuits and clamping high-voltage AC circuits electrically connected with the corresponding LC filter circuits. The clamping high-voltage alternating-current circuit is electrically connected with a rectifier diode; the rectifier diode comprises a forward rectification unit and a reverse rectification unit which are connected in parallel. A filtering common mode unit is electrically connected between the output ends of the three forward rectification units and the output ends of the three reverse rectification units; the filtering common-mode unit comprises an X safety capacitor CN1 and a common-mode inductor LN5 which are electrically connected; and one output end of the filtering common-mode unit is grounded, and the other output end of the filtering common-mode unit is connected with the drain electrode of the MOS tube device QN1 and the RC filtering current-limiting circuit in a branching manner. The device is reasonable in design, compact in structure and convenient to use.

Description

Technical Field

[0001] The utility model relates to a double high-voltage clamping protection rectifier filter circuit for an electric energy meter. Background Art

[0002] With the development of power electronics science and technology, traditional mechanical energy meters have been completely replaced by intelligent electronic energy meters. In view of the complex power grid environment for power consumption and transmission, how to solve the problem of voltage mutation or fault in the grid, such as ground fault, grid harmonic, unstable grid voltage, etc., to achieve high-voltage clamping to ensure the stable and reliable operation of intelligent energy meters is a common problem faced by the current intelligent energy meter industry. At present, there are very few high-voltage clamping protection circuits for intelligent energy meters in the energy meter industry, which are mainly divided into two categories: using a dedicated clamping module method; the advantages of this method are high accuracy and good consistency, and the disadvantages are that it depends on the packaging design of the module manufacturer, the module power is small, and it cannot be applied to the complex and changeable power grid environment requirements and the long-term high-power power demand of the energy meter; using a discrete component circuit method; the advantage of this method is that the power can be selected according to the actual needs of the MOS tube with different power, and its disadvantage is that the selection makes the circuit design complex and the voltage regulation accuracy is poor. Utility Model Content

[0003] The technical problem to be solved by the utility model is generally to provide a double high-voltage clamping protection rectifier filter circuit for an electric energy meter. The essence of the utility model is that the circuit can realize the double clamping protection circuit design for AC high voltage and DC high voltage, and at the same time has the characteristics of surge lightning protection and group pulse protection; the utility model of the circuit is applied to the field of smart electric meters.

[0004] In order to solve the above problems, the technical solution adopted by the utility model is:

[0005] A double high-voltage clamping protection rectifier filter circuit for an electric energy meter comprises three LC filter circuits and a clamping high-voltage AC circuit electrically connected to the corresponding LC filter circuits; the clamping high-voltage AC circuit is electrically connected to a rectifier diode;

[0006] The rectifier diode includes a forward rectifier unit and a reverse rectifier unit connected in parallel;

[0007] A common mode filtering unit is electrically connected between the output ends of the three-way forward rectifying unit and the output ends of the three-way reverse rectifying unit;

[0008] The common mode filtering unit includes an electrically connected X safety capacitor CN1 and a common mode inductor LN5;

[0009] One output end of the common mode filtering unit is grounded, and the other output end is connected to the drain of the MOS tube device QN1 and the RC filtering current limiting circuit;

[0010] The common mode filtering unit is grounded through the winding resistor RN42;

[0011] The RC filter current limiting circuit includes thick film resistors RN7, RN8, RN9 and a high voltage capacitor CN2;

[0012] The gate of the MOS transistor device QN1 is connected to the RC filter current limiting circuit through the thick film resistor RN10;

[0013] The source of the MOS transistor device QN1 is connected to HVCC, and the gate of the MOS transistor device QN1 is connected to the RC filter current limiting circuit.

[0014] As a further improvement of the above technical solution:

[0015] The LC filter circuit includes varistors RN1, RN2, RN3; common mode inductors LN1, LN2, LN3, and X safety capacitors CN22, CN23, CN24;

[0016] The varistor RN1, the common mode inductor LN1, and the X safety capacitor CN22 form the first LC filter circuit;

[0017] The varistor RN2, the common mode inductor LN2 and the X safety capacitor CN23 form the second LC filter circuit;

[0018] The varistor RN3, the common mode inductor LN3 and the X safety capacitor CN24 form the second LC filter circuit.

[0019] The clamped high-voltage AC circuit includes composite thermistors RN4, RN5, and RN6; the composite thermistors RN4, RN5, and RN6 are respectively the first, second, and third clamped high-voltage AC circuit units.

[0020] The rectifier diodes include forward diodes DN1, DN3, DN5, and reverse diodes DN2, DN4, DN6, DN7, DN8;

[0021] The rectifier diode includes a first rectifier unit including a forward diode DN1 and a reverse diode DN2 connected in parallel, a second rectifier unit including a forward diode DN3 and a reverse diode DN4 connected in parallel, and a third rectifier unit including a forward diode DN5 and a reverse diode DN6 connected in parallel.

[0022] A voltage stabilizing diode DN9 is connected between the source and the gate of the MOS transistor device QN1.

[0023] The high-voltage capacitor CN2 is connected in parallel with series-connected reverse-connected high-power TVS tubes DN10 and DN11; the other ends of the high-power TVS tubes DN10 and DN11 are grounded.

[0024] Thick film resistors RN7, RN8, and RN9 are arranged in series.

[0025] HVCC is connected to the ground through the thick film resistors RN11 and RN12 connected in series and then connected to the high voltage electrolytic capacitor EN1 in parallel, and then connected to the ground through the thick film resistors RN13 and RN14 connected in series and then connected to the high voltage electrolytic capacitor EN2 in parallel.

[0026] The utility model adopts a new circuit design method, using a double clamping form of a new composite thermistor clamp + a high-power MOS clamp circuit to clamp the ultra-high voltage input of the power grid, ensuring the safe and stable operation of the rear-stage circuit of the smart electric energy meter. It not only has the advantages of high clamping accuracy and high power, but also has the ability to resist surge lightning strikes and group pulses.

[0027] The utility model can increase the high-voltage clamping protection range by 1.2UN to 2.0UN through the combination of dual clamping circuits in different ways; increase the power range of the clamping circuit by combining dual clamping circuits in different ways, and additionally allocate the power of one original clamping circuit to another clamping circuit, thereby extending the service life of the device and increasing the safe and stable operation time of the product; the clamping voltage can be flexibly adjusted by combining dual clamping circuits in different ways, and the device parameters can be adjusted according to project requirements.

[0028] The utility model has the advantages of reasonable design, low cost, firmness and durability, safety and reliability, simple operation, time-saving, labor-saving, money-saving, compact structure and convenient use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the circuit structure of the utility model. DETAILED DESCRIPTION

[0030] like Figure 1 As shown, the double high-voltage clamping protection rectifier filter circuit for the electric energy meter of this embodiment is composed of the following devices: RN1, RN2, and RN3 are varistors, which play a role in lightning surge protection in the circuit; LN1, LN2, and LN3 are common-mode inductors, and CN22, CN23, and CN24 are X safety capacitors, which together form an LC filter circuit, which has the function of filtering differential-mode interference signals and voltage and current phase delay; RN4, RN5, and RN6 are composite thermistors, which mainly play the role of clamping the high-voltage AC circuit in the circuit;

[0031] DN1, DN2, DN3, DN4, DN5, DN6, DN7, and DN8 are rectifier diodes. The main function of this device in the circuit is rectification, converting AC power into DC power. CN1 is an X safety capacitor. The main function of this device in the circuit is primary filtering to obtain smoother DC power. LN5 is a common-mode inductor. The main function of this device in the circuit is to filter out common-mode interference signals within a certain frequency band. RN42 is a winding resistor. The main function of this device in the circuit is current limiting to prevent the subsequent circuit from being damaged by instantaneous high voltage breakdown. RN7, RN8, and RN9 are thick film resistors, which form an RC filter current limiting circuit with the CN2 high-voltage capacitor.

[0032] DN10 and DN11 are high-power TVS tubes. The main function of this device in the circuit is to adjust the clamping voltage value. RN10 is a thick film resistor. The main function of this device in the circuit is to limit the current and prevent damage to the subsequent MOS tube device. QN1 is a high-power MOS tube. The main function of this device in the circuit is to clamp the DC high voltage. DN9 is a voltage-stabilizing diode. The main function of this device in the circuit is to clamp the GS voltage of the MOS tube to prevent abnormal breakdown. EN1 and EN2 are high-voltage electrolytic capacitors. The main function of this device in the circuit is filtering, which further converts the pulsating DC voltage into a smooth DC voltage. RN11, RN12, RN13, and RN14 are thick film resistors. The main function of this device in the circuit is to balance the current flowing through EN1 and EN2.

[0033] The working process of the double high-voltage clamping protection rectifier filter circuit for electric energy meters is as follows:

[0034] When the three-phase AC input voltage of 1-UA, UB, UC, UN is at the normal voltage of 1.2UN, the voltage passes through the filter circuit composed of LN1, CN22, LN2, CN23 and LN3, CN24, and then passes through the composite thermistors RN4, RN5, RN6; because the voltage is within the normal range, the above composite thermistors are in action and there is no high-voltage clamping protection; then, the AC voltage is rectified by the three-phase full-wave rectifier circuit composed of DN1, DN2, DN3, DN4, DN5, DN6, DN7, DN8, and the AC voltage is rectified into a pulsed DC voltage; after the pulsed DC voltage is filtered and stored in the primary filter of CN1, the common-mode interference signal is filtered out through the common-mode inductor; the DC voltage passes through QN1, RN7, RN8, RN9, CN2 The high-voltage clamping circuit composed of DN10, DN11, RN10, DN9 and other devices does not work because the input AC voltage is within the normal range and the DC voltage after rectification and filtering is also within the normal range; the DC voltage all flows into the EN1, EN2 energy storage filter capacitors to obtain the voltage HVCC;

[0035] When the 2-UA, UB, UC, UN three-phase AC input voltage is in the normal voltage range of 1.2UN to 1.5UN, the voltage passes through the filter circuit composed of LN1, CN22, LN2, CN23 and LN3, CN24, and then passes through the composite thermistors RN4, RN5, RN6; since the voltage is within the non-operating range of the composite thermistor, the composite thermistor does not operate and there is no high-voltage clamping protection; subsequently, the AC voltage is rectified by the three-phase full-wave rectifier circuit composed of DN1, DN2, DN3, DN4, DN5, DN6, DN7, DN8 to rectify the AC voltage into a pulse DC voltage; after the pulse DC voltage is filtered and stored in the primary filter of CN1, the common-mode interference signal is filtered out by the common-mode inductor; the DC voltage passes through QN1, RN7, RN8, RN9, CN2 The high-voltage clamping circuit composed of DN10, DN11, RN10, DN9 and other devices, because the input AC voltage is out of range, the voltage after rectification and filtering has reached the MOS tube high-voltage clamping threshold, so this part of the circuit is activated to open the clamping protection, and the MOS tube device bears a certain part of the voltage; the remaining unclamped voltage flows into the EN1, EN2 energy storage filter capacitors to obtain the voltage HVCC;

[0036] When the 3-UA, UB, UC, UN three-phase AC input voltage is within the normal voltage range of 1.5UN to 2.0UN, the voltage passes through the filter circuit composed of LN1, CN22, LN2, CN23 and LN3, CN24, and then passes through the composite thermistors RN4, RN5, RN6; since the AC voltage reaches the composite thermistor action range, the composite thermistor action turns on the high-voltage clamping protection; the unclamped part of the voltage is rectified by the three-phase full-wave rectifier circuit composed of DN1, DN2, DN3, DN4, DN5, DN6, DN7, DN8, and the AC voltage is rectified into a pulsed DC voltage; after the pulsed DC voltage is filtered and stored by the primary filter of CN1, the common-mode interference signal is filtered out by the common-mode inductor; the DC voltage passes through the high-voltage clamping circuit composed of QN1, RN7, RN8, RN9, CN2 DN10, DN11, RN10, DN9 and other devices. Since the input AC voltage is out of range, there are two cases at this time:

[0037] a The voltage after rectification and filtering has reached the high-voltage clamping threshold of the MOS tube, so this part of the circuit is activated to turn on the clamping protection, and the MOS tube device bears a certain part of the voltage; the remaining unclamped voltage flows into the EN1 and EN2 energy storage filter capacitors to obtain the voltage HVCC;

[0038] b. The voltage after rectification and filtering does not reach the high-voltage clamping threshold of the MOS tube, so the clamping protection is not turned on in this part of the circuit, and the remaining unclamped voltage flows into the EN1 and EN2 energy storage filter capacitors to obtain the voltage HVCC;

[0039] The utility model uses an ingenious circuit design to combine the RN4, RN5, RN6 composite thermistor clamping protection circuit with the MOS tube clamping protection circuit to clamp different abnormal AC voltage input points; MOS tube clamping protection is used for 1.2UN to 1.5UN, and composite thermistor clamping protection is used for 1.5UN to 2.0UN. In this way, the double clamping protection method can increase the power of the clamping circuit; the utility model can be applied to other industries or circuits with higher power by adjusting and selecting different composite thermistors; clamping protection of different voltage ranges can be designed by adjusting and selecting QN1, DN10, DN11 parameters;

[0040] The present invention is fully described for a clearer disclosure, and the prior art will not be listed one by one.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it; although the utility model is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some of the technical features therein with equivalents; it is obvious for those skilled in the art to combine multiple technical solutions of the utility model. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the utility model.

Claims

1. A double high voltage clamping protection rectifier filter circuit for an electric energy meter, characterized in that: It includes three LC filter circuits and a clamped high-voltage AC circuit electrically connected to the corresponding LC filter circuits; the clamped high-voltage AC circuit is electrically connected to a rectifier diode; The rectifier diode includes a forward rectifier unit and a reverse rectifier unit connected in parallel; A common mode filtering unit is electrically connected between the output ends of the three-way forward rectifying unit and the output ends of the three-way reverse rectifying unit; The common mode filtering unit includes an electrically connected X safety capacitor CN1 and a common mode inductor LN5; One output end of the common mode filtering unit is grounded, and the other output end is connected to the drain of the MOS tube device QN1 and the RC filtering current limiting circuit; The common mode filtering unit is grounded through the winding resistor RN42; The RC filter current limiting circuit includes thick film resistors RN7, RN8, RN9 and a high voltage capacitor CN2; The gate of the MOS transistor device QN1 is connected to the RC filter current limiting circuit through the thick film resistor RN10; The source of the MOS transistor device QN1 is connected to HVCC, and the gate of the MOS transistor device QN1 is connected to the RC filter current limiting circuit.

2. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 1 is characterized in that: The LC filter circuit includes varistors RN1, RN2, RN3; common mode inductors LN1, LN2, LN3, and X safety capacitors CN22, CN23, CN24; The varistor RN1, the common mode inductor LN1, and the X safety capacitor CN22 form the first LC filter circuit; The varistor RN2, the common mode inductor LN2 and the X safety capacitor CN23 form the second LC filter circuit; The varistor RN3, the common mode inductor LN3 and the X safety capacitor CN24 form the second LC filter circuit.

3. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 1 is characterized in that: The clamped high-voltage AC circuit includes composite thermistors RN4, RN5, and RN6; the composite thermistors RN4, RN5, and RN6 are respectively the first, second, and third clamped high-voltage AC circuit units.

4. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 3 is characterized in that: The rectifier diodes include forward diodes DN1, DN3, DN5, and reverse diodes DN2, DN4, DN6, DN7, DN8; The rectifier diode includes a first rectifier unit including a forward diode DN1 and a reverse diode DN2 connected in parallel, a second rectifier unit including a forward diode DN3 and a reverse diode DN4 connected in parallel, and a third rectifier unit including a forward diode DN5 and a reverse diode DN6 connected in parallel.

5. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 4 is characterized in that: A voltage stabilizing diode DN9 is connected between the source and the gate of the MOS transistor device QN1.

6. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 5 is characterized in that: The high-voltage capacitor CN2 is connected in parallel with series-connected reverse-connected high-power TVS tubes DN10 and DN11; the other ends of the high-power TVS tubes DN10 and DN11 are grounded.

7. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 6 is characterized in that: Thick film resistors RN7, RN8, and RN9 are arranged in series.

8. The double high-voltage clamping protection rectifier filter circuit for electric energy meter according to claim 7 is characterized in that: HVCC is connected to the ground through the thick film resistors RN11 and RN12 connected in series and then connected to the high voltage electrolytic capacitor EN1 in parallel, and then connected to the ground through the thick film resistors RN13 and RN14 connected in series and then connected to the high voltage electrolytic capacitor EN2 in parallel.

Images