Switching power supply circuit and automatic reclosure applied by same

Abstract

The utility model provides a switching power supply circuit and an automatic reclosing lock. The switching power supply circuit comprises an AC input circuit; a rectifier bridge; the transformer comprises a primary winding, a secondary winding and an auxiliary winding and is provided with first to sixth ends; the fourth end and the sixth end are grounded; the power supply control unit comprises a switch input end, a feedback end, a power supply end and a locking end; the second end is coupled to the switch input end; the fifth end is coupled to the power supply end through the power supply circuit; the fifth end is coupled with the feedback end through the voltage sampling unit; the power supply control unit is configured to control the on-off of the switch input end and the grounding end according to a signal of the feedback end; the locking end locks the switch input end and the grounding end to be disconnected in response to a preset level appearing on the control signal circuit; the output circuit comprises a direct current output end, a grounding end, a first diode and an energy storage filter capacitor; the first diode is coupled to the DC output terminal and the third terminal. And the switching power supply circuit can be locked to completely close the power supply through the locking end, so that zero power consumption in a standby state is realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power supply, and in particular to a switching power supply circuit and an automatic reclosing switch applied thereto. Background Art

[0002] With the increasing development of smart grid and automatic control technology, fee-controlled smart energy meters have become widely popular. Currently, a large number of fee-controlled smart energy meters used in the market use external circuit breakers (also known as automatic reclosing switches) to control power on and off.

[0003] However, the automatic reclosing switch has an integrated power supply circuit, which is also powered by the mains electricity. Therefore, the power consumption of the automatic reclosing switch will also be included in the electricity meter. How to reduce its power consumption as much as possible to avoid affecting the normal billing of the electricity meter has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a switching power supply circuit and an automatic reclosing circuit to solve the problems in the related art.

[0005] The first aspect of the present disclosure provides a switch power supply circuit capable of standby, comprising: an AC input circuit; a rectifier bridge, comprising a rectifier input terminal and a rectifier output terminal, wherein the rectifier input terminal is coupled to the AC input circuit; a transformer, comprising: a primary winding, a secondary winding and an auxiliary winding; the primary winding comprises a first terminal coupled to the rectifier output terminal, and a second terminal; the secondary winding comprises a third terminal and a fourth terminal; the auxiliary winding comprises a fifth terminal and a sixth terminal; the voltages at both ends of the secondary winding and the auxiliary winding are in a preset proportional relationship; the fourth terminal and the sixth terminal are grounded; a power control unit, comprising a switch input terminal, a feedback terminal, a power supply terminal and a locking terminal; the second terminal is coupled to the switch input terminal; the The fifth terminal is coupled to the power supply terminal via a power supply circuit; the fifth terminal is coupled to the feedback terminal via a voltage sampling unit; the power control unit is configured to control the on and off of the switch input terminal and the ground terminal according to the signal of the feedback terminal; the locking terminal is coupled to the control signal line, and the power control unit is configured to lock the switch input terminal and the ground terminal to be disconnected in response to a preset level appearing on the control signal line; the output circuit includes: a DC output terminal, a ground terminal, a first diode and an energy storage filter capacitor; the two ends of the first diode are respectively coupled to the DC output terminal and the third terminal; the energy storage filter capacitor is coupled between the DC output terminal and the ground terminal; the second terminal, the third terminal and the fifth terminal are terminals of the same name.

[0006] In an embodiment of the first aspect, the output circuit further includes: a first resistor, a second resistor, a first capacitor and a second diode; the second diode is connected in parallel with the first diode in the same direction, the first resistor and the second resistor are connected in parallel, and one end of the parallel connection is coupled to the third end, and the other end of the parallel connection is coupled to the DC output end via the first capacitor.

[0007] In an embodiment of the first aspect, the output circuit further includes: a third energy storage filter capacitor, a fourth energy storage filter capacitor and a fifth resistor coupled in parallel between the DC output terminal and the ground terminal.

[0008] In an embodiment of the first aspect, the switching power supply circuit also includes: a peak absorption unit, including a third resistor, a fourth resistor, a sixth resistor, a seventh resistor, a second capacitor and a fourth diode; one end of the third resistor, the fourth resistor and the second capacitor is coupled to the rectifier output end; the other end of the third resistor and the fourth resistor is coupled to the other end of the second capacitor and one end of the sixth resistor and the seventh resistor, the other end of the sixth resistor and the seventh resistor is coupled to the cathode of the fourth diode, and the anode of the fourth diode is coupled to the second end.

[0009] In an embodiment of the first aspect, the rectifier output end is grounded via a first energy storage filter capacitor and a second energy storage filter capacitor connected in parallel.

[0010] In an embodiment of the first aspect, the voltage sampling unit includes a resistor voltage divider circuit, a voltage dividing point of the resistor voltage divider circuit is coupled to the feedback end; and a third capacitor is connected in parallel to both ends of a grounded resistor in the resistor voltage divider circuit.

[0011] In an embodiment of the first aspect, the AC input circuit includes a live wire terminal and a neutral wire terminal; the live wire terminal and / or the neutral wire terminal are coupled to the rectifier bridge via a fuse, and / or a varistor is coupled between the live wire terminal and the neutral wire terminal.

[0012] In an embodiment of the first aspect, the power supply circuit includes: a third diode, a tenth resistor and a fifth energy storage filter capacitor; the positive electrode of the third diode is coupled to the DC output end, the negative electrode of the third diode is coupled to one end of the tenth resistor, the other end of the tenth resistor is coupled to the power supply end and one end of the fifth energy storage filter capacitor, and the other end of the fifth energy storage filter capacitor is grounded.

[0013] In an embodiment of the first aspect, the power control unit includes a current detection terminal, which is grounded via a resistor; the current detection terminal is used to detect the current of the switch input terminal and generate an associated voltage output.

[0014] A second aspect of the present disclosure provides an automatic reclosing device, comprising: a switch power supply circuit capable of standby mode as described in any one of the first aspects.

[0015] As described above, the present disclosure provides a switching power supply circuit and an automatic reclosing switch, including: an AC input circuit; a rectifier bridge; a transformer, including: a primary winding, a secondary winding and an auxiliary winding, having a first to a sixth terminal; the fourth terminal and the sixth terminal are grounded; a power control unit, including a switch input terminal, a feedback terminal, a power supply terminal and a locking terminal; the second terminal is coupled to the switch input terminal; the fifth terminal is coupled to the power supply terminal via the power supply circuit; the fifth terminal is coupled to the feedback terminal via the voltage sampling unit; the power control unit is configured to control the on and off of the switch input terminal and the ground terminal according to the signal of the feedback terminal; the locking terminal locks the switch input terminal and the ground terminal to be disconnected in response to a preset level appearing on the control signal line; the output circuit includes: a DC output terminal, a ground terminal, a first diode and an energy storage filter capacitor; the first diode is coupled to the DC output terminal and the third terminal; the energy storage filter capacitor is coupled to the DC output terminal. The switching power supply circuit can be locked by the locking terminal to completely turn off the power supply, so as to achieve zero power consumption in the standby state. It is beneficial to improve the problem of unexpected power consumption of the external circuit breaker of the electric meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram showing the structure of a switching power supply circuit in an embodiment of the present disclosure is shown.

[0017] Figure 2 A schematic diagram showing the structure of a locking end of a processor coupled to a power control unit in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0018] The following is an explanation of the embodiments of the present disclosure by specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the information disclosed by the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in the present disclosure can also be modified or changed in various ways according to different viewpoints and application modules without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0019] The following is a detailed description of the embodiments of the present disclosure with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0020] In the representations of the present disclosure, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" and the like mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials or characteristics represented may be combined in any one or a group of embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present disclosure and the features of different embodiments or examples, unless they are mutually contradictory.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the representation of the present disclosure, "a group" means two or more, unless otherwise clearly and specifically defined.

[0022] In order to clearly describe the present disclosure, components not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0023] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0024] Although the terms first, second, etc. are used to represent various elements in this article in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate that there are the described features, steps, operations, elements, modules, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or a group of other features, steps, operations, elements, modules, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0025] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present disclosure. The singular form used herein also includes the plural form unless the sentence clearly indicates the contrary meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0026] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present disclosure belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with relevant technical literature and the message of the present disclosure, and shall not be overly interpreted as ideal or very formal meanings unless defined.

[0027] At present, fee-controlled smart meters generally use external circuit breakers (i.e., automatic reclosing switches) to control power on and off. However, the power consumption of the automatic reclosing switch will be included in the meter, affecting the normal billing of the meter and resulting in additional electricity costs for users.

[0028] In view of this, a switching power supply circuit is provided in an embodiment of the present disclosure, which can achieve zero standby power consumption through a simple circuit, thereby reducing power consumption to solve the problems in the related art. Among them, standby refers to the state when the output end of the switching power supply circuit is not connected to a load, and the smaller the standby power consumption of the power supply, the better.

[0029] like Figure 1 As shown, a circuit structure schematic diagram of a switching power supply circuit in an embodiment of the present disclosure is shown.

[0030] exist Figure 1 In the figure, the switching power supply circuit includes: an AC input circuit, a rectifier bridge (DB1), a transformer (T1), a power control unit (U1) and an output circuit.

[0031] The input circuit includes a live wire terminal (L) and a neutral wire terminal (N), wherein the live wire terminal is used to connect to the live wire of the alternating current, and the neutral wire terminal is used to connect to the neutral wire of the alternating current.

[0032] Optionally, the input circuit further includes a varistor (MOV1) coupled between the live wire terminal and the neutral wire terminal. The varistor forms a current loop between the live wire terminal and the neutral wire terminal. When an overvoltage or surge current is generated in the circuit, the current will preferentially pass through the parallel varistor to achieve a protective effect.

[0033] Optionally, a fuse (F1) may be provided between the live wire end and the rectifier bridge. Optionally, a winding resistor (FR1) may be provided between the neutral wire end and the rectifier bridge. When the input current is too large, the fuse generates more heat, and will automatically melt, cut off the circuit, and play an overcurrent protection role. On the one hand, the function of the winding resistor is similar to that of a fuse. When the input current is too large, the winding resistor generates more heat, and will automatically melt, cut off the circuit, and play an overcurrent protection role; on the other hand, it can also play a certain role in lightning strike surge protection.

[0034] exist Figure 1 In the figure, the rectifier bridge is drawn in a simplified manner, including two rectifier input terminals (AC) coupled to L and N respectively, a rectifier output terminal (i.e., output positive electrode V+) outputting the rectified voltage, and a grounded output negative terminal (V-). Optionally, an energy storage filter capacitor can be arranged between the rectifier output terminal and the ground to play the role of storage, discharge and filtering on the input side, such as the first energy storage filter capacitor (EC1) and the second energy storage filter capacitor (EC2) connected in parallel in the figure. In fact, in the circuit principle diagram, the rectifier bridge can be composed of, for example, 4 diodes connected in parallel.

[0035] The transformer includes a primary winding (L1), a secondary winding (L2) and an auxiliary winding (L3). The primary winding includes a first end coupled to the rectifier output end, and a second end. Figure 1 The first end and the second end are respectively at upper and lower positions. The secondary winding includes a third end and a fourth end, Figure 1 The third end and the fourth end are respectively at upper and lower positions. The auxiliary winding includes a fifth end and a sixth end, Figure 1 The fifth end and the sixth end are at the upper and lower positions respectively. The energy consumed by the secondary winding and the auxiliary winding comes from the energy storage of the primary winding. The voltages across the secondary winding and the auxiliary winding are in a preset proportional relationship, and the preset proportional relationship can be determined according to the turns ratio between the secondary winding and the auxiliary winding, such as 1:3, then the voltage ratio between the secondary winding and the auxiliary winding is 3:1. For example, when the voltage across the auxiliary winding is 36V, the voltage on the secondary winding is 12V. The fourth end and the sixth end are grounded. Among them, the second end, the third end and the fifth end are ends of the same name. Optionally, the fourth end can also be grounded via a filter capacitor (CY1) to suppress primary-secondary common-mode interference.

[0036] The output circuit includes a DC output terminal (+12V for example), a ground terminal, a first diode (D1) and an output energy storage filter capacitor.

[0037] The two ends of the first diode are coupled to the DC output terminal and the third terminal respectively. As an example, the anode of the first diode is coupled to the third terminal, and the cathode of the first diode is coupled to the DC output terminal. In other embodiments, based on the different working modes of the switching power supply, the circuit structure can be changed. For example, if the connection mode of L2 is opposite, then D1 can also be compared to Figure 1 The connections are opposite, and a reverse diode can also be connected between the DC output terminal and the ground.

[0038] Exemplarily, the output circuit further includes: a first resistor (R1), a second resistor (R2), a first capacitor (C1) and a second diode (D2). The second diode is connected in parallel with the first diode in the same direction to shunt current and avoid overheating. The first resistor and the second resistor are connected in parallel, and one end of the parallel connection is coupled to the third end, and the other end of the parallel connection is coupled to the DC output end via the first capacitor. R1, R2 and C1 constitute a protection circuit, a resistor-capacitor absorption circuit, and absorb the high-voltage pulse voltage generated instantly in the circuit, especially to prevent the reverse high-voltage pulse voltage from breaking through the first diode and the second diode.

[0039] Exemplarily, the output energy storage capacitor may be one or more. Figure 1 In the figure, a third energy storage filter capacitor (EC3) and a fourth energy storage filter capacitor (EC4) are shown to be coupled in parallel between the DC output terminal and the ground terminal. For example, a fifth resistor (R5) can also be coupled between the DC output terminal and the ground terminal, so that the switching power supply has a certain current control capability, pulls down the increased voltage, and avoids loss of control. At the same time, when the power is off, the residual electric energy in the circuit is released through R3, which plays a role in protection and stable output.

[0040] The power control unit includes a switch input terminal (SW), a feedback terminal (FB), a power supply terminal (VDD) and a locking terminal (ZC). And corresponding to the power supply terminal, the power control unit may also include a grounding terminal. The second terminal is coupled to the switch input terminal to output the rectified voltage to the switch input terminal. The fifth terminal is coupled to the power supply terminal via a power supply circuit, and the auxiliary winding generates a voltage in a preset proportion to the output voltage of the secondary winding based on the energy obtained from the primary winding, and supplies power to U1. The fifth terminal is coupled to the feedback terminal via a voltage sampling unit. Since the output voltage of the secondary winding is ultimately output as the output voltage of the switching power supply circuit, such as a DC 12V output, based on the preset proportional relationship, the voltage on the auxiliary winding actually forms a sampling of the output voltage of the switching power supply circuit. The voltage on the auxiliary winding is sampled by the voltage sampling unit and input to the feedback terminal, which actually realizes the sampling of the output voltage. Therefore, it can be determined whether the output voltage is stable at 12V output according to the sampled voltage at the feedback terminal, so that it can be adjusted when it is unstable.

[0041] The power control unit is configured to control the on / off of the switch input terminal and the ground terminal according to the signal of the feedback terminal. Specifically, when the switch input terminal and the ground terminal are turned on, that is, the path from SW to GND is turned on, the primary winding flows through the current from the first end to the second end, completing the energy storage of the primary winding, and also the energy storage of the input measured capacitor (such as EC1, EC2, etc.). According to the principle that the potentials at both ends of the transformer with the same polarity are maintained, the current direction of the secondary winding is reversely cut off by D1 at this time, so there is no current on the secondary winding. However, if there is stored electrical energy in CE1 in the previous cycle, it will be discharged at this time to maintain the +12V DC output of the DC output terminal.

[0042] The locking terminal is coupled to the control signal line, and the power control unit is configured to lock the switch input terminal and the ground terminal to be disconnected in response to a preset level (e.g., a high level) appearing on the control signal line. In some embodiments, the power control unit has a built-in MOS tube, the drain (D) of the MOS tube leads to the switch input terminal, the source leads to the ground terminal, and the gate (G) is coupled to be controlled by the feedback terminal to control the switching frequency of the third input terminal and the third ground terminal to stabilize the output voltage of the DC output terminal. The locking terminal can lock the voltage on the gate to keep the D and S terminals disconnected, and further lock the primary coil to not store energy, so that the power supply of the entire switching power supply circuit is turned off, so that it can be realized in the standby state.

[0043] Exemplarily, the power supply circuit includes a third diode (D3), a tenth resistor (R10) and a fifth energy storage filter capacitor (C5). The anode of the third diode is coupled to the DC output terminal, the cathode of the third diode is coupled to one end of the tenth resistor, the other end of the tenth resistor is coupled to the power supply terminal and one end of the fifth energy storage filter capacitor, and the other end of the fifth energy storage filter capacitor is grounded.

[0044] Exemplarily, the power control unit includes a current detection terminal, which is grounded via a resistor; the current detection terminal is used to detect the current at the switch input terminal and generate an associated voltage output.

[0045] Exemplarily, the voltage sampling unit includes a resistor voltage divider circuit, and the voltage dividing point of the resistor voltage divider circuit is coupled to the feedback terminal. Specifically, the resistor voltage divider circuit may include an eighth resistor, an eleventh resistor and a thirteenth resistor connected in series from the fifth terminal to the ground in sequence. The voltage dividing point is located at the connection point of the thirteenth resistor and the eleventh resistor. It is understandable that the specific implementation of the resistor voltage divider circuit can be set as needed, and is not limited to this. The two ends of the resistor (exemplified as the thirteenth resistor) connected to the ground in the resistor voltage divider circuit can be connected in parallel with a third capacitor (C3), which can stabilize the voltage at the FB terminal and avoid feedback fluctuations.

[0046] Specifically explain the working principle of the switching power supply circuit.

[0047] When the switch input terminal and the ground terminal of the power control unit are turned on, the second terminal of the primary winding is turned on to the ground, and current flows through the primary winding to store energy. Current flows from the first terminal to the second terminal of the primary winding to complete the energy storage of the primary winding. The energy storage filter capacitor on the input side (such as EC1, EC2, etc.) can also store energy. According to the principle that the potentials at both ends of the transformer with the same name maintain the same polarity, the current direction of the secondary winding is reversely cut off by D1 (and D2) at this time, so there is no current on the secondary winding. However, if there is stored energy in CE1 in the previous cycle, it will be discharged at this time to maintain the +12V DC output at the DC output terminal.

[0048] When the switch input terminal of the power control unit is disconnected from the ground terminal, the path from the second end of the primary winding to the ground is disconnected, and no energy is stored. Current flows through the secondary winding, and forwardly passes through D1 to store energy in the output capacitor and to supply power to the load connected to the DC output terminal and the second ground terminal.

[0049] The auxiliary winding is used to obtain feedback of the output voltage of the secondary winding and to supply power to U1. According to the principle of the same-name terminal, the auxiliary winding cooperates with D3 in a similar working principle to the secondary winding cooperates with D1 and D2. When the primary winding stores energy, D3 limits the current from the auxiliary winding to the power supply terminal; when the primary winding does not store energy, D3 turns on the auxiliary winding.

[0050] The load consumes energy from the secondary winding and the output energy storage capacitor. When the output voltage drops, the feedback terminal will sample this situation and trigger the power control unit to increase the on-off frequency of the switch input terminal and the ground terminal to maintain the output voltage stable at +12V; or, when the output voltage rises, the feedback terminal will sample this situation and trigger the power control unit to reduce the on-off frequency of the switch input terminal and the ground terminal to maintain +12V stability.

[0051] Exemplarily, the power control unit includes a current detection terminal (CS), which is grounded via a resistor, for example, a ninth resistor (R9) and a twelfth resistor (R12) connected in parallel. The current detection terminal is used to detect the current at the switch input terminal and generate an associated voltage output in cooperation with the connected resistor. Whether the current of the SW input (i.e., the current of the primary winding) is overcurrent can be determined based on whether the voltage at the current detection terminal is higher than the nominal value. When overcurrent occurs, the SW and GND terminals can be disconnected to avoid burning of the internal MOS.

[0052] In some embodiments, the power control unit can be implemented by a power control chip, such as a power control chip with a locking terminal of model PN6367 or a related series. As an example, it can include multiple SW pins, which can be connected and coupled to the second end of the transformer to increase the current carrying capacity.

[0053] In some embodiments, the switching power supply circuit may further include a peak absorption unit, including a third resistor (R3), a fourth resistor (R4), a sixth resistor (R6), a seventh resistor (R7), a second capacitor (C2) and a fourth diode (D4). One end of the third resistor, the fourth resistor and the second capacitor is coupled to the rectifier output end; the other end of the third resistor and the fourth resistor is coupled to the other end of the second capacitor and one end of the sixth resistor and the seventh resistor, the other end of the sixth resistor and the seventh resistor is coupled to the cathode of the fourth diode, and the anode of the fourth diode is coupled to the second end.

[0054] In some embodiments, the control signal circuit may be coupled to a processor, such as an MCU. Figure 2 As shown, a schematic diagram of the circuit structure of the signal line between the locking end and the MCU in one embodiment of the present disclosure is shown. An I / O port of the MCU is connected to one end of the fourteenth resistor (R14), and the other end of R14 is connected to one end of the fourth capacitor (C4) and the locking end. R14 and C4 are connected in series to form a coupling circuit. When the switching power supply circuit is in standby mode, the processor sends a high-level signal to the locking end to turn off the voltage output of the switching power supply circuit during the standby time to achieve zero standby power consumption.

[0055] In another embodiment of the present disclosure, an automatic reclosing switch may be provided, comprising a switch power supply circuit capable of standby mode as described in any of the previous embodiments.

[0056] In summary, the present disclosure provides a switching power supply circuit and an automatic reclosing switch, including: an AC input circuit; a rectifier bridge; a transformer, including: a primary winding, a secondary winding and an auxiliary winding, having a first to a sixth terminal; the fourth terminal and the sixth terminal are grounded; a power control unit, including a switch input terminal, a feedback terminal, a power supply terminal and a locking terminal; the second terminal is coupled to the switch input terminal; the fifth terminal is coupled to the power supply terminal via the power supply circuit; the fifth terminal is coupled to the feedback terminal via the voltage sampling unit; the power control unit is configured to control the on and off of the switch input terminal and the ground terminal according to the signal of the feedback terminal; the locking terminal locks the switch input terminal and the ground terminal to be disconnected in response to a preset level appearing on the control signal line; the output circuit includes: a DC output terminal, a ground terminal, a first diode and an energy storage filter capacitor; the first diode is coupled to the DC output terminal and the third terminal; the energy storage filter capacitor is coupled to the DC output terminal. The switching power supply circuit can be locked by the locking terminal to completely turn off the power supply, so as to achieve zero power consumption in the standby state. It is beneficial to improve the problem of unexpected power consumption of the external circuit breaker of the electric meter.

[0057] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure shall still be covered by the protection scope of the present disclosure.

Claims

1. A switching power supply circuit capable of standby operation, characterized in that: include: AC input circuit; A rectifier bridge, comprising a rectifier input terminal and a rectifier output terminal, wherein the rectifier input terminal is coupled to the AC input circuit; A transformer, comprising: a primary winding, a secondary winding and an auxiliary winding; the primary winding comprises a first end coupled to the rectifier output end, and a second end; the secondary winding comprises a third end and a fourth end; the auxiliary winding comprises a fifth end and a sixth end; the voltages at both ends of the secondary winding and the auxiliary winding are in a preset proportional relationship; the fourth end and the sixth end are grounded; A power control unit, comprising a switch input terminal, a feedback terminal, a power supply terminal and a locking terminal; the second terminal is coupled to the switch input terminal; the fifth terminal is coupled to the power supply terminal via a power supply circuit; the fifth terminal is coupled to the feedback terminal via a voltage sampling unit; the power control unit is configured to control the on / off of the switch input terminal and the ground terminal according to a signal at the feedback terminal; the locking terminal is coupled to a control signal circuit, and the power control unit is configured to lock the switch input terminal and the ground terminal to be disconnected in response to a preset level appearing on the control signal circuit; The output circuit includes: a DC output terminal, a ground terminal, a first diode and an output energy storage filter capacitor; the two ends of the first diode are respectively coupled to the DC output terminal and the third terminal; the output energy storage filter capacitor is coupled between the DC output terminal and the ground terminal; the second terminal, the third terminal and the fifth terminal are the same-name terminals.

2. The switching power supply circuit according to claim 1, characterized in that: The output circuit also includes: a first resistor, a second resistor, a first capacitor and a second diode; the second diode is connected in parallel with the first diode in the same direction, the first resistor and the second resistor are connected in parallel, and one end of the parallel connection is coupled to the third end, and the other end of the parallel connection is coupled to the DC output end via the first capacitor.

3. The switching power supply circuit according to claim 1, characterized in that: The output circuit further includes: a third energy storage filter capacitor, a fourth energy storage filter capacitor and a fifth resistor which are coupled in parallel between the DC output terminal and the ground terminal.

4. The switching power supply circuit according to claim 1, characterized in that: Also includes: A peak absorption unit, comprising a third resistor, a fourth resistor, a sixth resistor, a seventh resistor, a second capacitor and a fourth diode; The third resistor, the fourth resistor and one end of the second capacitor are coupled to the rectifier output end; the other ends of the third resistor and the fourth resistor are coupled to the other end of the second capacitor and one ends of the sixth resistor and the seventh resistor, the other ends of the sixth resistor and the seventh resistor are coupled to the cathode of the fourth diode, and the anode of the fourth diode is coupled to the second end.

5. The switching power supply circuit according to claim 1, characterized in that: The rectifier output terminal is grounded via a first energy storage filter capacitor and a second energy storage filter capacitor connected in parallel.

6. The switching power supply circuit according to claim 1, characterized in that: The voltage sampling unit comprises a resistor voltage divider circuit, a voltage dividing point of the resistor voltage divider circuit is coupled to the feedback end; two ends of a grounded resistor in the resistor voltage divider circuit are connected in parallel with a third capacitor.

7. The switching power supply circuit according to claim 1, characterized in that: The AC input circuit includes a live wire terminal and a neutral wire terminal; the live wire terminal and / or the neutral wire terminal are coupled to the rectifier bridge via a fuse, and / or a varistor is coupled between the live wire terminal and the neutral wire terminal.

8. The switching power supply circuit according to claim 1, characterized in that: The power supply circuit includes: a third diode, a tenth resistor and a fifth energy storage filter capacitor; the positive electrode of the third diode is coupled to the DC output end, the negative electrode of the third diode is coupled to one end of the tenth resistor, the other end of the tenth resistor is coupled to the power supply end and one end of the fifth energy storage filter capacitor, and the other end of the fifth energy storage filter capacitor is grounded.

9. The switching power supply circuit according to claim 1, characterized in that: The power control unit comprises a current detection terminal, which is grounded via a resistor; the current detection terminal is used to detect the current at the switch input terminal and generate an associated voltage output.

10. An automatic reclosing device, characterized in that: include: A switching power supply circuit capable of standby operation as claimed in any one of claims 1 to 9.

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