Flyback switching power supply circuit for intelligent electric meter

Abstract

The utility model relates to a flyback switching power supply circuit for an intelligent electric meter, which comprises a voltage stabilizing circuit, a photoelectric coupling circuit, a power supply input circuit, a power supply control circuit and a power supply output circuit, and is characterized in that the photoelectric coupling circuit is respectively connected with the power supply output circuit and the power supply control circuit; and the voltage stabilizing circuit is respectively connected with the power supply control circuit, the power supply output circuit and the power supply input circuit. According to the utility model, the RCD absorption circuit is used for counteracting the instantaneous voltage peak of leakage inductance, so that the stability of the whole power supply circuit is improved; the photoelectric coupling circuit is arranged to ensure that overcurrent does not cause damage to the secondary side circuit, and meanwhile, the power supply control circuit is arranged to suppress interference.

Description

Technical Field

[0001] The utility model relates to the field of switch power supply circuits for electric meters, in particular to a flyback switch power supply circuit for intelligent electric meters. Background Art

[0002] As a vital part of electronic products, the stability and anti-interference ability of switching power supply have always been technical difficulties. With the continuous progress of materials and power electronics technology, switching power supply is currently developing towards high frequency and high stability. The switching power supply keeps the output voltage stable by adjusting the time ratio of the switch off and on. At present, the biggest interference in the flyback circuit is that the voltage spike exists at the D port of the transistor MOSFET when it is working, which causes damage to the switching power supply.

[0003] Currently, the widely used electronic devices with flyback switching power supplies all have the problem of large leakage inductance, which will reduce the working efficiency of the transformer in the switching power supply. At the same time, the leakage inductance will also generate back electromotive force, which may break down the switch tube. The current common practice is to add an RCD absorption circuit on the primary side of the transformer and achieve electrical isolation between the various parts of the circuit. Utility Model Content

[0004] The utility model aims to solve the above problems and provides a flyback switching power supply circuit for a smart electric meter to solve the above problems.

[0005] A flyback switch power supply circuit for a smart meter comprises: a voltage stabilizing circuit, a photoelectric coupling circuit, a power input circuit, a power control circuit and a power output circuit, wherein the photoelectric coupling circuit is connected to the power output circuit and the power control circuit respectively, and the voltage stabilizing circuit is connected to the power control circuit, the power output circuit and the power input circuit respectively.

[0006] Preferably, the power input circuit comprises an inductor LN1, a capacitor CN1, a varistor RN2 and a composite thermistor RN1, and the capacitor CN1, the varistor RN2 and the composite thermistor RN1 are all connected to the inductor LN1.

[0007] Preferably, the voltage stabilizing circuit includes a rectifier bridge chip DN1, an electrolytic capacitor EN2, an electrolytic capacitor EN3, a resistor RN4, a resistor RN8, a resistor RN10, a resistor RN12, a resistor RN15, a transformer T1, a resistor RN3, a resistor RN7, a capacitor CN5 and a diode DN4; the electrolytic capacitor EN2, the resistor RN4, the resistor RN3, the capacitor CN5 and the transformer T1 are all connected to the rectifier bridge chip DN1; the resistor RN8, the resistor RN10 and the electrolytic capacitor EN3 are all connected to the electrolytic capacitor EN2; the resistor RN12 is connected to the resistor RN10; the resistor RN15 is connected to the resistor RN12; the resistor RN7 and the diode DN4 are all connected to the capacitor CN5.

[0008] Preferably, the power control circuit includes capacitor CN8, power management chip UN1, diode DN5, resistor RN9, electrolytic capacitor EN4, capacitor CN10, resistor RN16, resistor RN17, capacitor CN9, resistor RN14 and capacitor CN11, and the capacitor CN8, capacitor CN9, resistor RN14, capacitor CN11, resistor RN16, resistor RN17, electrolytic capacitor EN4, capacitor CN10 and resistor RN9 are all connected to the power management chip UN1, and the diode DN5 is connected to the resistor RN9.

[0009] Preferably, the photoelectric coupling circuit includes capacitor CN12, photoelectric coupler DN6, resistor RN11, resistor RN13, resistor RN18, capacitor CN13, resistor R1, resistor R2, resistor R3 and voltage regulator UN2, the capacitor CN12, resistor RN11, resistor RN13, resistor RN18 and voltage regulator UN2 are all connected to the photoelectric coupler DN6, the capacitor CN13 is connected to the resistor RN18, the resistor R1 is connected to the resistor RN11, and the resistor R2 and the resistor R3 are both connected to the capacitor CN13.

[0010] Preferably, the power supply output circuit includes a diode DN2, a resistor RN6, a capacitor CN2, a capacitor CN6, a capacitor CN3, a capacitor CN4, a capacitor CN7, an electrolytic capacitor EN1, a diode DN3 and a resistor RN5; the diode DN2, the capacitor CN2, the capacitor CN6, the capacitor CN3, the capacitor CN4, the electrolytic capacitor EN1, the capacitor CN7 and the resistor RN5 are all connected to the diode DN3; and the resistor RN6 is connected to the capacitor CN2.

[0011] Preferably, the varistor RN2 is connected between the live terminal L and the neutral terminal N, the inductor LN1 and the capacitor CN1 form an LC filter, and the composite thermistor RN1 is used to suppress the surge current generated by the surge voltage when the circuit is open.

[0012] Preferably, a capacitor CN14 is further included, and two ends of the capacitor CN14 are respectively connected to the ground line GND and the protection ground PGND.

[0013] Preferably, the power management chip UN1 is a HF920GS chip.

[0014] Preferably, the rectifier bridge chip DN1 is MB10S.

[0015] The utility model has the following advantages: using the RCD absorption circuit to offset the instantaneous voltage spike of the leakage inductance, thereby improving the stability of the entire power supply circuit; by setting a photoelectric coupling circuit to ensure that overcurrent will not cause damage to the secondary side circuit, and at the same time setting a power supply control circuit to suppress interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only one embodiment of the utility model. For ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0017] Figure 1 : Schematic diagram of the circuit structure of the utility model. DETAILED DESCRIPTION

[0018] The utility model is further described below with reference to the accompanying drawings and examples:

[0019] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] like Figure 1 As shown, a flyback switch power supply circuit for a smart meter includes: a voltage stabilizing circuit, a photoelectric coupling circuit, a power input circuit, a power control circuit and a power output circuit, wherein the photoelectric coupling circuit is connected to the power output circuit and the power control circuit respectively, and the voltage stabilizing circuit is connected to the power control circuit, the power output circuit and the power input circuit respectively.

[0023] Preferably, the power input circuit includes an inductor LN1, a capacitor CN1, a varistor RN2 and a composite thermistor RN1, wherein the capacitor CN1, the varistor RN2 and the composite thermistor RN1 are all connected to the inductor LN1. The composite thermistor RN1 includes two components, namely a thermistor θ and a varistor U.

[0024] Preferably, the voltage stabilizing circuit includes a rectifier bridge chip DN1, an electrolytic capacitor EN2, an electrolytic capacitor EN3, a resistor RN4, a resistor RN8, a resistor RN10, a resistor RN12, a resistor RN15, a transformer T1, a resistor RN3, a resistor RN7, a capacitor CN5 and a diode DN4; the electrolytic capacitor EN2, the resistor RN4, the resistor RN3, the capacitor CN5 and the transformer T1 are all connected to the rectifier bridge chip DN1; the resistor RN8, the resistor RN10 and the electrolytic capacitor EN3 are all connected to the electrolytic capacitor EN2; the resistor RN12 is connected to the resistor RN10; the resistor RN15 is connected to the resistor RN12; the resistor RN7 and the diode DN4 are all connected to the capacitor CN5.

[0025] Preferably, the power control circuit includes capacitor CN8, power management chip UN1, diode DN5, resistor RN9, electrolytic capacitor EN4, capacitor CN10, resistor RN16, resistor RN17, capacitor CN9, resistor RN14 and capacitor CN11, and the capacitor CN8, capacitor CN9, resistor RN14, capacitor CN11, resistor RN16, resistor RN17, electrolytic capacitor EN4, capacitor CN10 and resistor RN9 are all connected to the power management chip UN1, and the diode DN5 is connected to the resistor RN9.

[0026] Preferably, the photoelectric coupling circuit includes capacitor CN12, photoelectric coupler DN6, resistor RN11, resistor RN13, resistor RN18, capacitor CN13, resistor R1, resistor R2, resistor R3 and voltage regulator UN2, the capacitor CN12, resistor RN11, resistor RN13, resistor RN18 and voltage regulator UN2 are all connected to the photoelectric coupler DN6, the capacitor CN13 is connected to the resistor RN18, the resistor R1 is connected to the resistor RN11, and the resistor R2 and the resistor R3 are both connected to the capacitor CN13.

[0027] Preferably, the power supply output circuit includes a diode DN2, a resistor RN6, a capacitor CN2, a capacitor CN6, a capacitor CN3, a capacitor CN4, a capacitor CN7, an electrolytic capacitor EN1, a diode DN3 and a resistor RN5; the diode DN2, the capacitor CN2, the capacitor CN6, the capacitor CN3, the capacitor CN4, the electrolytic capacitor EN1, the capacitor CN7 and the resistor RN5 are all connected to the diode DN3; and the resistor RN6 is connected to the capacitor CN2.

[0028] Preferably, the varistor RN2 is connected between the live terminal L and the neutral terminal N, and the inductor LN1 and the capacitor CN1 form an LC filter for filtering power supply noise.

[0029] Preferably, the composite thermistor RN1 is used to suppress surge current generated by surge voltage when the circuit is open.

[0030] Preferably, a capacitor CN14 is further included, and two ends of the capacitor CN14 are respectively connected to the ground line GND and the protection ground PGND.

[0031] Preferably, the power management chip UN1 is a HF920GS chip.

[0032] Preferably, the rectifier bridge chip DN1 is MB10S.

[0033] Working principle:

[0034] The AC power is first rectified by the rectifier bridge in the power input circuit, and then filtered by the filter capacitor to output DC power. Before the circuit is started, the voltage of the capacitor on VCC can be charged to the starting voltage of the power management chip UN1 because of the charging of the auxiliary winding of the transformer. If the circuit fails to start at once, the VCC of the power management chip UN1 cannot start due to the low winding voltage value.

[0035] When the voltage output terminal Vout after the voltage division by resistors R1, R2, and R3 is greater than the voltage value of the voltage regulator tube UN2, the light-emitting diode inside the photocoupler DN6 is turned on and emits light, the photocoupler DN6 is turned on, the voltage is transmitted to the feedback pin 6 of the power management chip UN1, and the MOS tube inside the power management chip UN1 is disconnected; when the voltage output terminal Vout after the voltage division by resistors R1, R2, and R3 is less than the voltage value of the voltage regulator tube UN2, the voltage regulator tube UN2 is disconnected, the photocoupler DN6 is not turned on, and the MOS tube inside the power management chip UN1 is turned on. Therefore, the photocoupler DN6 not only couples and transmits signals, but also has the function of isolating interference.

[0036] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A flyback switching power supply circuit for a smart meter, characterized in that: include: A voltage stabilizing circuit, a photoelectric coupling circuit, a power input circuit, a power control circuit and a power output circuit, wherein the photoelectric coupling circuit is connected to the power output circuit and the power control circuit respectively, and the voltage stabilizing circuit is connected to the power control circuit, the power output circuit and the power input circuit respectively.

2. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The power input circuit includes an inductor LN1, a capacitor CN1, a varistor RN2 and a composite thermistor RN1. The capacitor CN1, the varistor RN2 and the composite thermistor RN1 are all connected to the inductor LN1.

3. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The voltage stabilizing circuit includes a rectifier bridge chip DN1, an electrolytic capacitor EN2, an electrolytic capacitor EN3, a resistor RN4, a resistor RN8, a resistor RN10, a resistor RN12, a resistor RN15, a transformer T1, a resistor RN3, a resistor RN7, a capacitor CN5 and a diode DN4. The electrolytic capacitor EN2, the resistor RN4, the resistor RN3, the capacitor CN5 and the transformer T1 are all connected to the rectifier bridge chip DN1, the resistor RN8, the resistor RN10 and the electrolytic capacitor EN3 are all connected to the electrolytic capacitor EN2, the resistor RN12 is connected to the resistor RN10, the resistor RN15 is connected to the resistor RN12, and the resistor RN7 and the diode DN4 are all connected to the capacitor CN5.

4. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The power control circuit includes capacitor CN8, power management chip UN1, diode DN5, resistor RN9, electrolytic capacitor EN4, capacitor CN10, resistor RN16, resistor RN17, capacitor CN9, resistor RN14 and capacitor CN11. The capacitor CN8, capacitor CN9, resistor RN14, capacitor CN11, resistor RN16, resistor RN17, electrolytic capacitor EN4, capacitor CN10 and resistor RN9 are all connected to the power management chip UN1, and the diode DN5 is connected to the resistor RN9.

5. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The photoelectric coupling circuit includes capacitor CN12, photoelectric coupler DN6, resistor RN11, resistor RN13, resistor RN18, capacitor CN13, resistor R1, resistor R2, resistor R3 and voltage regulator UN2. The capacitor CN12, resistor RN11, resistor RN13, resistor RN18 and voltage regulator UN2 are all connected to the photoelectric coupler DN6, the capacitor CN13 is connected to the resistor RN18, the resistor R1 is connected to the resistor RN11, and the resistor R2 and the resistor R3 are both connected to the capacitor CN13.

6. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The power supply output circuit includes a diode DN2, a resistor RN6, a capacitor CN2, a capacitor CN6, a capacitor CN3, a capacitor CN4, a capacitor CN7, an electrolytic capacitor EN1, a diode DN3 and a resistor RN5. The diode DN2, the capacitor CN2, the capacitor CN6, the capacitor CN3, the capacitor CN4, the electrolytic capacitor EN1, the capacitor CN7 and the resistor RN5 are all connected to the diode DN3, and the resistor RN6 is connected to the capacitor CN2.

7. The flyback switching power supply circuit for a smart meter according to claim 2, characterized in that: The varistor RN2 is connected between the live terminal L and the neutral terminal N, the inductor LN1 and the capacitor CN1 form an LC filter, and the composite thermistor RN1 is used to suppress the surge current generated by the surge voltage when the circuit is open.

8. The flyback switching power supply circuit for a smart meter according to claim 1, characterized in that: The device further comprises a capacitor CN14, wherein two ends of the capacitor CN14 are respectively connected to a ground line GND and a protection ground PGND.

9. The flyback switching power supply circuit for a smart meter according to claim 4, characterized in that: The power management chip UN1 is a HF920GS chip.

10. The flyback switching power supply circuit for a smart meter according to claim 3, characterized in that: The rectifier bridge chip DN1 is MB10S.

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