Switching power supply circuit with under-voltage protection and direct-current circuit breaker

Abstract

The embodiment of the utility model provides a switching power supply circuit with under-voltage protection and a direct-current circuit breaker, and the circuit is characterized in that one end of a transient voltage suppressor is connected with an external power supply end, and the other end of the transient voltage suppressor is grounded; the input end of the input energy storage filter circuit is coupled with an external power supply end; the power supply end is coupled with the output end of the input energy storage filter circuit; a positive electrode of a first voltage stabilizing diode in the input under-voltage protection circuit is grounded through a first resistor, and a negative electrode of the first voltage stabilizing diode is coupled with a power supply end. The enabling end is coupled with the positive electrode of the first voltage stabilizing diode; the first end of the primary coil is coupled with the power supply end, and the second end is coupled with the power output end; the input end of each output circuit is coupled with the secondary coil, and the output end of each output circuit is connected with an external load; one of the at least one output circuit is coupled with the feedback end through a feedback circuit. According to the invention, the power supply circuit can adapt to a large range of input voltage changes, and provides independent power supply output for at least two isolated loads.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power supply circuits, and in particular to a switching power supply circuit with undervoltage protection and a DC circuit breaker. Background Art

[0002] In existing power supply technologies, especially in complex environments such as 5G base stations and photovoltaic inverters, power supply systems often face the challenges of large fluctuations in input voltage, multiple loads, and electrical isolation between loads. Traditional switching power supply designs often find it difficult to simultaneously provide efficient and stable power supply to multiple loads over a wide range of input voltages, especially when encountering input voltage undervoltage conditions, which can easily lead to power failure or load abnormality.

[0003] Existing power solutions usually use independent power supplies to power each load, but this not only increases the cost and size of the system, but is also not conducive to efficient resource utilization and system miniaturization. In addition, many power products may cause damage to the power chip or unstable system operation due to the lack of an effective undervoltage protection mechanism when the input voltage changes greatly, and cannot meet the strict requirements of power supply voltage accuracy and stability for isolated loads such as motors and communication modules in 5G base stations and photovoltaic inverters. 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 a DC circuit breaker with undervoltage protection to solve the problems in the related art.

[0005] A first aspect of the present disclosure provides a switching power supply circuit with undervoltage protection, comprising:

[0006] A transient voltage suppressor tube, one end of which is connected to an external power supply terminal, and the other end of which is grounded;

[0007] An input energy storage filter circuit, wherein an input end of the input energy storage filter circuit is coupled to the external power supply end;

[0008] A power chip, the power chip comprising: a power supply terminal, an enable terminal, a power output terminal, a feedback terminal and a chip ground terminal;

[0009] The power supply end is coupled to the output end of the input energy storage filter circuit;

[0010] The chip ground terminal is grounded;

[0011] An input undervoltage protection circuit, the input undervoltage protection circuit comprising:

[0012] A first voltage stabilizing diode, wherein an anode of the first voltage stabilizing diode is grounded via a first resistor, and a cathode of the first voltage stabilizing diode is coupled to the power supply end;

[0013] The enable terminal is coupled to the anode of the first voltage stabilizing diode;

[0014] A transformer, the transformer comprising a primary coil and at least one secondary coil;

[0015] The primary coil comprises a first end and a second end, the first end is coupled to the power supply end, and the second end is coupled to the power output end;

[0016] At least one output circuit, the input end of each output circuit is coupled to the secondary coil, and the output end of each output circuit is connected to an external load;

[0017] One of the at least one output circuit is coupled to the feedback terminal via a feedback circuit;

[0018] The power chip controls the connection and disconnection between the power output terminal and the chip ground terminal according to the feedback signal provided by the feedback circuit to connect and disconnect the power supply circuit of the primary coil to adjust the output voltage of the at least one output circuit.

[0019] In an embodiment of the first aspect, the input energy storage filter circuit includes:

[0020] A first energy storage filter capacitor, wherein a positive electrode of the first energy storage filter capacitor is coupled to the transient voltage suppression tube, and a negative electrode of the first energy storage filter capacitor is grounded;

[0021] A second energy storage filter capacitor, wherein the second energy storage filter capacitor is connected in parallel with the first energy storage filter capacitor;

[0022] A first inductor, one end of the first inductor is coupled to the external power supply end, and the other end of the first inductor is coupled to the positive electrode of the second energy storage filter capacitor.

[0023] In an embodiment of the first aspect, an RCD absorption circuit is further provided between the primary coil and the input undervoltage protection circuit, and the RCD absorption circuit includes:

[0024] a second resistor, one end of the second resistor being coupled to the first end;

[0025] a third resistor, the third resistor being connected in parallel with the second resistor;

[0026] A first capacitor, wherein the first capacitor is connected in parallel with the third resistor;

[0027] A first diode, wherein an anode of the first diode is coupled to the second end, and a cathode of the first diode is coupled to the other end of the second resistor.

[0028] In an embodiment of the first aspect, the at least one secondary coil comprises a first secondary coil, and the first secondary coil comprises a third end and a fourth end;

[0029] The feedback circuit comprises:

[0030] An optical coupling transmission component, the optical coupling transmission component comprising a receiver and a transmitter; one end of the receiver is grounded through a fourth resistor, and the other end of the receiver is coupled to the feedback end;

[0031] One end of the transmitter is coupled to the third end through a fifth resistor;

[0032] A three-terminal parallel adjustable voltage regulator, wherein the negative electrode of the three-terminal parallel adjustable voltage regulator is grounded, and the positive electrode of the three-terminal parallel adjustable voltage regulator is coupled to the other end of the transmitter;

[0033] A feedback voltage circuit, wherein an input terminal of the feedback voltage circuit is coupled to an output terminal of a first output circuit, a ground terminal of the feedback voltage circuit is grounded, and an output terminal of the feedback voltage circuit between the input terminal and the ground terminal is coupled to a reference terminal of the three-terminal parallel adjustable regulator to output a feedback voltage;

[0034] A sixth resistor, one end of the sixth resistor is coupled to the fifth resistor, and the other end of the sixth resistor is coupled to the other end of the transmitter.

[0035] In an embodiment of the first aspect, the feedback voltage circuit includes:

[0036] a seventh resistor, one end of the seventh resistor being coupled to the external load, and the other end of the seventh resistor being grounded through an eighth resistor;

[0037] A connection point between the seventh resistor and the eighth resistor leads to an output end of the feedback voltage circuit.

[0038] In an embodiment of the first aspect, the feedback circuit further includes a loop compensation circuit, and the loop compensation circuit includes:

[0039] A second capacitor, one end of the second capacitor is coupled to the other end of the transmitter, and the other end of the second capacitor is coupled to the output end of the feedback voltage circuit through a ninth resistor.

[0040] In an embodiment of the first aspect, the first output circuit includes:

[0041] a first output rectifier circuit, wherein an input terminal of the first output rectifier circuit is coupled to the third terminal;

[0042] The output energy storage filter circuit comprises: a second inductor, one end of the second inductor is coupled to the output end of the first output rectifier circuit, and the other end of the second inductor is connected to the external load;

[0043] a third energy storage filter capacitor, wherein a positive electrode of the third energy storage filter capacitor is coupled to one end of the second inductor, and a negative electrode of the third energy storage filter capacitor is grounded;

[0044] a fourth energy storage filter capacitor, wherein a positive electrode of the fourth energy storage filter capacitor is coupled to the other end of the second inductor, and a negative electrode of the fourth energy storage filter capacitor is grounded;

[0045] A third capacitor, wherein the third capacitor and the fourth energy storage filter capacitor are connected in parallel between the output terminal of the first output circuit and the ground terminal;

[0046] A tenth resistor is connected in parallel with the third capacitor.

[0047] In an embodiment of the first aspect, the first output rectifier circuit includes:

[0048] a second zener diode, wherein an anode of the second zener diode is coupled to the third end, and a cathode of the second zener diode is coupled to one end of the second inductor;

[0049] An eleventh resistor, one end of the eleventh resistor is coupled to the anode of the second voltage-stabilizing diode, and the other end of the eleventh resistor is coupled to the cathode of the second voltage-stabilizing diode via a fourth capacitor.

[0050] In an embodiment of the first aspect, the secondary coil includes a second secondary coil, and the second secondary coil includes a fifth end and a sixth end;

[0051] The at least one output circuit includes a second output circuit, an input end of the second output circuit is coupled to the second secondary coil; the second output circuit includes:

[0052] a third voltage stabilizing diode, wherein an anode of the third voltage stabilizing diode is coupled to the fifth end, and a cathode of the third voltage stabilizing diode is coupled to the external load;

[0053] a fifth energy storage filter capacitor, wherein a positive electrode of the fifth energy storage filter capacitor is coupled to the fifth end, and a negative electrode of the fifth energy storage filter capacitor is grounded;

[0054] A fifth capacitor, the fifth capacitor being connected in parallel with the fifth energy storage filter capacitor;

[0055] A twelfth resistor is connected in parallel with the fifth capacitor.

[0056] A second aspect of the present disclosure provides a DC circuit breaker, comprising any one of the switching power supply circuits with undervoltage protection described above.

[0057] The beneficial effects of the present disclosure are as follows: by integrating a transient voltage suppression tube and an input energy storage filter circuit, transient overvoltage and noise in the input power supply are effectively absorbed and filtered out, so that the power supply circuit can adapt to a wide range of input voltage changes, and the electrical isolation of the power supply is achieved through a transformer, providing independent power output for at least two isolated loads (such as a motor and a communication module), effectively avoiding mutual interference between the loads and ensuring the safe operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A circuit schematic diagram showing a switching power supply circuit with undervoltage protection in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] like Figure 1 , which shows a circuit principle schematic diagram of a switching power supply circuit with undervoltage protection in an embodiment of the present disclosure.

[0069] The switching power supply circuit with undervoltage protection includes: a transient voltage suppressor tube TVS, an input energy storage filter circuit, a power chip, an input undervoltage protection circuit, and at least one output circuit;

[0070] One end of the transient voltage suppressor TVS is connected to the external power supply terminal VIN1, and the other end of the transient voltage suppressor TVS is grounded;

[0071] The input end of the input energy storage filter circuit is coupled to the external power supply end VIN1;

[0072] The power chip comprises: a power supply terminal VIN2, an enable terminal EN, a power output terminal SW, a feedback terminal FB and a chip ground terminal GND1;

[0073] The power supply terminal VIN2 is coupled to the output terminal of the input energy storage filter circuit;

[0074] The chip ground terminal GND1 is grounded;

[0075] The input undervoltage protection circuit comprises: a first voltage stabilizing diode DW1;

[0076] The anode of the first voltage stabilizing diode DW1 is grounded via a first resistor, and the cathode of the first voltage stabilizing diode DW1 is coupled to the power supply terminal VIN2;

[0077] The enable terminal EN is coupled to the anode of the first voltage stabilizing diode DW1;

[0078] A transformer T, wherein the transformer T comprises a primary coil and at least one secondary coil;

[0079] The primary coil includes a first end 1 and a second end 2, the first end 1 is coupled to the power supply end VIN2, and the second end 2 is coupled to the power output end SW;

[0080] The input end of each output circuit is coupled to the secondary coil, and the output end of each output circuit is connected to an external load f0;

[0081] One of the at least one output circuit is coupled to the feedback terminal FB via a feedback circuit;

[0082] The power chip controls the connection and disconnection of the power output terminal SW and the chip ground terminal GND1 according to the feedback signal provided by the feedback circuit to connect and disconnect the power supply circuit of the primary coil to adjust the output voltage of the at least one output circuit.

[0083] Specifically, in the prior art, traditional switching power supply designs often find it difficult to simultaneously achieve efficient and stable power supply to multiple loads under a wide range of input voltages, especially when encountering an input voltage undervoltage condition, which can easily lead to power failure or abnormal load operation.

[0084] exist Figure 1 In the embodiment, a switching power supply circuit is shown to include: a transient voltage suppressor TVS, an input energy storage filter circuit, a power chip, an input undervoltage protection circuit, and at least one output circuit.

[0085] One end of the transient voltage suppressor TVS is directly connected to the external power supply terminal VIN1 to absorb and suppress transient overvoltage at the power input terminal to protect the subsequent circuit from impact; the other end is grounded to ensure that the transient current can be discharged smoothly.

[0086] The input end of the input energy storage filter circuit is coupled to the external power supply end VIN1, and the output end is coupled to the power supply end VIN2 of the power chip to provide a relatively smooth and stable DC voltage.

[0087] The power chip is provided with a power supply terminal VIN2, an enable terminal EN, a power output terminal SW, a feedback terminal FB and a chip ground terminal GND1. The power supply terminal VIN2 is connected to the output of the input energy storage filter circuit, and the chip ground terminal GND1 is grounded.

[0088] The input undervoltage protection circuit includes a first voltage zener diode DW1 and a first resistor. The positive electrode of the first voltage zener diode DW1 is grounded through the first resistor, and the negative electrode is coupled to the power supply terminal VIN2 of the power chip. The enable terminal EN of the power chip is valid at a high level. When the input voltage from VIN1 obtained by VIN2 is lower than the preset threshold (which can be the reverse breakdown voltage of DW1), the first voltage zener diode DW1 cannot be reversely broken down, so the EN terminal is grounded to a low level through R1, and the power chip cannot be enabled to work. When the voltage of VIN2 is greater than the preset threshold and reversely breaks down DW1, the voltage at the EN terminal is pulled up to a high level, and the power chip is enabled to work at this time. It can be understood from this that only when the voltage at the VIN2 terminal, that is, the power supply voltage of the power chip, is high enough (reaching the preset threshold), can the power chip be enabled to work; when the power supply voltage of the power chip is not high enough, the power chip will not work, and can be protected by undervoltage.

[0089] The transformer T performs voltage conversion and isolation, and the transformer T includes a primary coil and at least one secondary coil. The first end 1 of the primary coil is connected to the power supply terminal VIN2 of the power chip, and the second end 2 is connected to the power output terminal SW. Optionally, the second end 2 and the third end 3 are the same end.

[0090] At least one output circuit, the input end of each output circuit is respectively coupled with the secondary coil of the transformer T, and the output end thereof is used to connect the corresponding external load f0. Among them, at least one output circuit is coupled with the feedback end FB of the power chip through the feedback circuit to form a closed-loop control.

[0091] A thirteenth resistor R13 is connected in series between the feedback terminal FB and the ground terminal.

[0092] The power chip controls the on / off of the power output terminal SW and the chip ground terminal GND1 in a timely manner according to the feedback signal provided by the feedback circuit, thereby adjusting the power supply circuit of the primary coil, and then accurately controlling the output voltage of at least one output circuit, ensuring that each load can obtain stable and efficient power supply under a wide range of input voltages.

[0093] Optionally, in some embodiments, the power chip model may be XL6019 and related series chips with similar functions, or a power control chip from other manufacturers with similar principles.

[0094] Optionally, a fifth capacitor C11 is connected in parallel between the energy storage filter circuit and the input undervoltage protection circuit for filtering.

[0095] Optionally, the input energy storage filter circuit includes:

[0096] A first energy storage filter capacitor C1, wherein a positive electrode of the first energy storage filter capacitor C1 is coupled to the transient voltage suppression tube TVS, and a negative electrode of the first energy storage filter capacitor C1 is grounded;

[0097] A second energy storage filter capacitor C2, wherein the second energy storage filter capacitor C2 is connected in parallel with the first energy storage filter capacitor C1;

[0098] A first inductor L1 , one end of which is coupled to the external power supply terminal VIN1 , and the other end of which is coupled to the positive electrode of the second energy storage filter capacitor C2 .

[0099] Optionally, the positive electrode of the first energy storage filter capacitor C1 is coupled to the output end of the transient voltage suppressor tube TVS, that is, a circuit node located between the transient voltage suppressor tube TVS and the power supply terminal VIN2 of the power chip. The negative electrode of the first energy storage filter capacitor C1 is directly grounded to absorb high-frequency noise in the power supply and provide instantaneous power reserve to ensure the stability of the power supply voltage.

[0100] The second energy storage filter capacitor C2 is connected in parallel with the first energy storage filter capacitor C1 to enhance the filtering effect and improve the power quality, filter out the AC ripple in the power supply to a greater extent, and provide a larger capacitance reserve to ensure that the power chip can be continuously and stably powered when the input voltage fluctuates.

[0101] One end of the first inductor L1 is directly coupled to the external power supply terminal VIN1, and the other end is coupled to the positive electrode of the second energy storage filter capacitor C2. The first inductor L1 is used for filtering and energy storage, which can suppress high-frequency interference in the input power supply, and slow down the change speed of the voltage through self-inductance when the power supply voltage suddenly changes, and jointly construct an LC filter network with the filter capacitor to significantly improve the purity and stability of the power supply.

[0102] Optionally, an RCD absorption circuit is further provided between the primary coil and the input undervoltage protection circuit, and the RCD absorption circuit includes:

[0103] A second resistor R2, one end of the second resistor R2 is coupled to the first end 1;

[0104] A third resistor R3, the third resistor R3 is connected in parallel with the second resistor R2;

[0105] A first capacitor C3, wherein the first capacitor C3 is connected in parallel with the third resistor R3;

[0106] A first diode D1 , wherein an anode of the first diode D1 is coupled to the second end 2 , and a cathode of the first diode D1 is coupled to the other end of the second resistor R2 .

[0107] Optionally, an RCD absorption circuit is provided between the primary coil and the input undervoltage protection circuit. The RCD absorption circuit is composed of a second resistor R2, a third resistor R3, a first capacitor C3 and a first diode D1.

[0108] One end of the second resistor R2 is directly coupled to the first end 1 of the primary coil, serving as an input end of the RCD absorption circuit for sensing voltage changes on the primary coil.

[0109] The third resistor R3 is connected in parallel with the second resistor R2, and the two together constitute the resistive element part in the RCD absorption circuit, which can provide damping during the back electromotive force generated by the primary coil, consume part of the energy through the resistance, thereby effectively suppressing voltage overshoot and protecting the switching device and the transformer T from damage.

[0110] The first capacitor C3 is connected in parallel across the third resistor R3 to form an RC absorption network together with the resistor. The first capacitor C3 can store a portion of energy when the back electromotive force is generated and then release it slowly, which helps to smooth voltage changes and reduce the impact of voltage spikes on the system.

[0111] The positive electrode of the first diode D1 is coupled to the second end 2 of the primary coil, and the negative electrode is coupled to the other end of the second resistor R2, forming a freewheeling loop. When the voltage of the primary coil is reversed, the first diode D1 is turned on, providing a low impedance path to quickly discharge the reverse current to the ground, thereby effectively clamping the reverse voltage and preventing the excessive voltage from causing harm to the system.

[0112] Optionally, the at least one secondary coil includes a first secondary coil, and the first secondary coil includes a third end 3 and a fourth end 4;

[0113] The feedback circuit comprises:

[0114] An optical coupling transmission component U1, the optical coupling transmission component U1 includes a receiver U11 and a transmitter U12; one end of the receiver U11 is grounded through a fourth resistor, and the other end of the receiver U11 is coupled to the feedback end FB;

[0115] One end of the transmitter U12 is coupled to the third end 3 through a fifth resistor R5;

[0116] A three-terminal parallel adjustable voltage regulator U2, wherein the negative electrode of the three-terminal parallel adjustable voltage regulator U2 is grounded, and the positive electrode of the three-terminal parallel adjustable voltage regulator U2 is coupled to the other end of the transmitter U12;

[0117] A feedback voltage circuit, wherein an input terminal of the feedback voltage circuit is coupled to an output terminal of a first output circuit, a ground terminal of the feedback voltage circuit is grounded, and an output terminal of the feedback voltage circuit between the input terminal and the ground terminal is coupled to a reference terminal of the three-terminal parallel adjustable regulator U2 to output a feedback voltage;

[0118] A sixth resistor R6 , one end of the sixth resistor R6 is coupled to the fifth resistor R5 , and the other end of the sixth resistor R6 is coupled to the other end of the transmitter U12 .

[0119] Optionally, the at least one secondary coil includes a first secondary coil, and the first secondary coil includes a third end 3 and a fourth end 4 .

[0120] The optical coupler transmission component U1 consists of a receiver U11 and a transmitter U12. One end of the receiver U11 is grounded through a fourth resistor, and the other end is coupled to the feedback end FB of the power chip to receive the feedback signal. One end of the transmitter U12 is coupled to the third end 3 of the first secondary coil through a fifth resistor R5 to collect voltage information on the secondary coil.

[0121] A three-terminal parallel adjustable voltage regulator U2 is used as a processing element for the feedback signal, and its negative electrode is grounded to ensure the stability of the voltage reference. The positive electrode of the voltage regulator is coupled with the other end of the transmitter U12 of the optical coupler transmission component U1 to receive the voltage signal after optical coupler isolation.

[0122] The input terminal of the feedback voltage circuit is coupled to the output terminal of a first output circuit for detecting the actual output voltage level. The ground terminal of the feedback voltage circuit is grounded, and between the input terminal and the ground terminal, the output terminal of the feedback voltage circuit is connected to the reference terminal of the three-terminal parallel adjustable regulator U2 to generate the feedback voltage.

[0123] One end of the sixth resistor R6 is connected to the fifth resistor R5, and the other end is connected to the other end of the transmitter U12 of the optical coupling transmission component U1. By adjusting the resistance value of the sixth resistor R6, the strength and accuracy of the feedback signal can be further optimized.

[0124] Optionally, the feedback voltage circuit includes:

[0125] a seventh resistor R7, one end of the seventh resistor R7 is coupled to the external load f0, and the other end of the seventh resistor R7 is grounded via an eighth resistor R8;

[0126] A connection point between the seventh resistor R7 and the eighth resistor R8 leads to an output end of the feedback voltage circuit.

[0127] Optionally, the feedback voltage circuit includes a seventh resistor R7 and an eighth resistor R8. One end of the seventh resistor R7 is directly coupled to the external load f0, and the load current flows through the seventh resistor R7, so that a voltage drop is generated across the seventh resistor R7, and the voltage drop reflects the feedback voltage source of the actual working state of the load.

[0128] The other end of the seventh resistor R7 is connected in series with an eighth resistor R8 and then grounded. The seventh resistor R7 and the eighth resistor R8 together form a resistor voltage divider circuit, and the connection point between them is the voltage dividing point connected to the output end of the feedback voltage circuit. The voltage value output by the output end of the feedback voltage circuit is obtained after the seventh resistor R7 and the eighth resistor R8 divide the voltage, and this voltage value is in a certain proportional relationship with the output voltage of f0, so as to realize the feedback of the output voltage.

[0129] The feedback voltage circuit is used to obtain an accurate feedback voltage reflecting the load state so as to facilitate the control system to accurately regulate the output voltage.

[0130] As an example, the feedback voltage will be introduced into the feedback terminal FB of the power chip, thereby realizing closed-loop control, ensuring that the output voltage is automatically adjusted following the load change, and achieving the purpose of constant voltage or constant current control. In different application scenarios, the resistance values ​​of the seventh resistor R7 and the eighth resistor R8 can be adjusted to adapt to different voltage feedback requirements and load characteristics.

[0131] Optionally, the feedback circuit further includes a loop compensation circuit, and the loop compensation circuit includes:

[0132] A second capacitor C4, one end of the second capacitor C4 is coupled to the other end of the transmitter U12, and the other end of the second capacitor C4 is coupled to the output end of the feedback voltage circuit through a ninth resistor R9.

[0133] Optionally, the loop compensation circuit is composed of a second capacitor C4 and a ninth resistor R9. One end of the second capacitor C4 is connected to the other end of the transmitter U12 in the optical coupling transmission component U1, that is, the output end of the feedback signal after the optical coupling isolation. The second capacitor C4 prevents the power supply system from oscillating when the load changes or the input voltage fluctuates.

[0134] The other end of the second capacitor C4 is coupled to the output end of the feedback voltage circuit through the ninth resistor R9. The ninth resistor R9 plays the role of voltage division and current limiting. Through the loop compensation circuit, the switching power supply circuit in this embodiment can more effectively provide a stable voltage output that meets the accuracy requirements for the load under a wide range of input voltages, while enhancing the robustness and stability of the system when facing rapidly changing loads and input voltages.

[0135] Optionally, the first output circuit includes:

[0136] A first output rectifier circuit, wherein an input terminal of the first output rectifier circuit is coupled to the third terminal 3;

[0137] The output energy storage filter circuit comprises: a second inductor L2, one end of the second inductor L2 is coupled to the output end of the first output rectifier circuit, and the other end of the second inductor L2 is connected to the external load f0;

[0138] A third energy storage filter capacitor C5, wherein a positive electrode of the third energy storage filter capacitor C5 is coupled to one end of the second inductor L2, and a negative electrode of the third energy storage filter capacitor C5 is grounded;

[0139] A fourth energy storage filter capacitor C6, wherein a positive electrode of the fourth energy storage filter capacitor C6 is coupled to the other end of the second inductor L2, and a negative electrode of the fourth energy storage filter capacitor C6 is grounded;

[0140] A third capacitor C7, wherein the third capacitor C7 and the fourth energy storage filter capacitor C6 are connected in parallel between the output end of the first output circuit and the ground end;

[0141] The tenth resistor R10 is connected in parallel with the third capacitor C7.

[0142] Optionally, the input end of the first output rectifier circuit in the first output circuit is coupled to the third end 3 of the first secondary coil, responsible for rectifying and outputting the voltage output by the secondary coil of the transformer T (ie, the third end 3 of the first secondary coil).

[0143] The output energy storage filter circuit is mainly composed of a second inductor L2, a third energy storage filter capacitor C5, a fourth energy storage filter capacitor C6 and a third capacitor C7. Among them, one end of the second inductor L2 is connected to the output end of the first output rectifier circuit, and the other end thereof is connected to the external load f0, which plays the role of filtering and energy storage, so as to reduce the fluctuation of the output voltage and provide a continuous and stable current for the load.

[0144] The third energy storage filter capacitor C5 and the fourth energy storage filter capacitor C6 are connected in parallel at both ends of the second inductor L2, and respectively assume the functions of filtering and energy storage. The positive electrode of the third energy storage filter capacitor C5 is coupled to one end of the second inductor L2 connected to the load, and the negative electrode is grounded; the positive electrode of the fourth energy storage filter capacitor C6 is also coupled to the load end of the second inductor L2, and the negative electrode is also grounded.

[0145] In addition, in order to further optimize the filtering effect and improve the stability of the power supply output, a third capacitor C7 is provided between the output terminal and the ground terminal of the first output circuit, and is connected in parallel with the fourth energy storage filter capacitor C6. At the same time, the tenth resistor R10 is connected in parallel with the third capacitor C7. Such a design can adjust the output impedance and improve the ripple suppression capability of the output voltage, so that the power supply can work stably and efficiently under various load conditions.

[0146] Optionally, the first output rectifier circuit includes:

[0147] a second voltage stabilizing diode DW2, wherein an anode of the second voltage stabilizing diode DW2 is coupled to the third terminal 3, and a cathode of the second voltage stabilizing diode DW2 is coupled to one end of the second inductor L2;

[0148] An eleventh resistor R11 , one end of the eleventh resistor R11 is coupled to the anode of the second voltage zener diode DW2 , and the other end of the eleventh resistor R11 is coupled to the cathode of the second voltage zener diode DW2 via a fourth capacitor C8 .

[0149] Optionally, the rectifier circuit includes a second voltage stabilizing diode DW2, an eleventh resistor R11, and a fourth capacitor C8.

[0150] The second voltage stabilizing diode DW2 is used as a rectifying element, and its positive electrode is coupled to the third end 3 of the first secondary coil, i.e., the input end of the rectifying circuit, for receiving the AC voltage output by the secondary coil of the transformer T. The negative electrode of the second voltage stabilizing diode DW2 is coupled to one end of the second inductor L2 in the output energy storage filter circuit. Here, the second voltage stabilizing diode DW2 plays the role of half-wave rectification, allowing the voltage to be conducted only in one half cycle, and converting the AC voltage into a unidirectional pulsating DC voltage.

[0151] In order to further optimize the rectification effect and protect the voltage-stabilizing diode, an eleventh resistor R11 and a fourth capacitor C8 are added. One end of the eleventh resistor R11 is connected to the positive electrode of the second voltage-stabilizing diode DW2, and the other end is coupled to the negative electrode of the second voltage-stabilizing diode DW2 through the fourth capacitor C8. The eleventh resistor R11 mainly plays a current limiting role, limiting the maximum current passing through the voltage-stabilizing diode to prevent it from being damaged due to excessive current. The fourth capacitor C8, as a buffer capacitor, can absorb the voltage spikes generated during the rectification process, smooth the pulsating DC voltage, and also provide transient current support for the voltage-stabilizing diode, thereby enhancing the stability of the rectification circuit.

[0152] Optionally, the secondary coil includes a second secondary coil, and the second secondary coil includes a fifth end 5 and a sixth end 6;

[0153] The at least one output circuit includes a second output circuit, an input end of the second output circuit is coupled to the second secondary coil; the second output circuit includes:

[0154] a third voltage stabilizing diode DW3, wherein an anode of the third voltage stabilizing diode DW3 is coupled to the fifth end 5, and a cathode of the third voltage stabilizing diode DW3 is coupled to the external load f0;

[0155] A fifth energy storage filter capacitor C9, wherein a positive electrode of the fifth energy storage filter capacitor C9 is coupled to the fifth end 5, and a negative electrode of the fifth energy storage filter capacitor C9 is grounded;

[0156] A fifth capacitor C8, the fifth capacitor C10 is connected in parallel with the fifth energy storage filter capacitor C9;

[0157] A twelfth resistor R12, wherein the twelfth resistor R12 is connected in parallel with the fifth capacitor C10.

[0158] Optionally, the switching power supply circuit with undervoltage protection includes, in addition to the first secondary coil, a second secondary coil, the second secondary coil including a fifth terminal 5 and a sixth terminal 6. Based on this, at least one output circuit includes a second output circuit coupled to the second secondary coil, for providing a stable DC voltage to other loads. Further, the second terminal 2 and the fifth terminal 5 are terminals of the same name.

[0159] The second output circuit includes: a third voltage stabilizing diode DW3, a fifth energy storage filter capacitor C9, a fifth capacitor C10, and a twelfth resistor R12.

[0160] The anode of the third voltage stabilizing diode DW3 is coupled to the fifth terminal 5 of the second secondary coil, and is used to receive the voltage transformed by the transformer T. When the voltage exceeds the preset threshold, the third voltage stabilizing diode DW3 plays a voltage stabilizing role to ensure the stability of the output voltage. Its cathode is directly connected to the external load f0 to provide the load with stabilized DC power.

[0161] The positive electrode of the fifth energy storage filter capacitor C9 is also coupled to the fifth terminal 5 of the second secondary coil, and the negative electrode is grounded, so as to effectively reduce voltage fluctuation and noise through energy storage and filtering functions.

[0162] The fifth capacitor C10 is connected in parallel with the fifth energy storage filter capacitor C9 to form a filter network, which further enhances the voltage smoothing effect and improves the output quality of the power supply.

[0163] The twelfth resistor R12 and the fifth capacitor C10 are connected in parallel to the circuit. By adjusting the resistance value, the output impedance can be properly adjusted to optimize the system frequency response characteristics and ensure the stability of the power supply under different load conditions.

[0164] In yet another embodiment of the present disclosure, a DC circuit breaker is provided, which includes the switching power supply circuit with undervoltage protection in any of the above embodiments.

[0165] 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 with undervoltage protection, characterized in that: include: A transient voltage suppressor tube, one end of which is connected to an external power supply terminal, and the other end of which is grounded; An input energy storage filter circuit, wherein an input end of the input energy storage filter circuit is coupled to the external power supply end; A power chip, the power chip comprising: a power supply terminal, an enable terminal, a power output terminal, a feedback terminal and a chip ground terminal; The power supply end is coupled to the output end of the input energy storage filter circuit; The chip ground terminal is grounded; An input undervoltage protection circuit, the input undervoltage protection circuit comprising: A first voltage stabilizing diode, wherein an anode of the first voltage stabilizing diode is grounded via a first resistor, and a cathode of the first voltage stabilizing diode is coupled to the power supply end; The enable terminal is coupled to the anode of the first voltage stabilizing diode; A transformer, the transformer comprising a primary coil and at least one secondary coil; The primary coil comprises a first end and a second end, the first end is coupled to the power supply end, and the second end is coupled to the power output end; At least one output circuit, the input end of each output circuit is coupled to the secondary coil, and the output end of each output circuit is connected to an external load; One of the at least one output circuit is coupled to the feedback terminal via a feedback circuit; The power chip controls the connection and disconnection between the power output terminal and the chip ground terminal according to the feedback signal provided by the feedback circuit to connect and disconnect the power supply circuit of the primary coil to adjust the output voltage of the at least one output circuit.

2. The switching power supply circuit with undervoltage protection according to claim 1, characterized in that: The input energy storage filter circuit comprises: A first energy storage filter capacitor, wherein a positive electrode of the first energy storage filter capacitor is coupled to the transient voltage suppression tube, and a negative electrode of the first energy storage filter capacitor is grounded; A second energy storage filter capacitor, wherein the second energy storage filter capacitor is connected in parallel with the first energy storage filter capacitor; A first inductor, one end of the first inductor is coupled to the external power supply end, and the other end of the first inductor is coupled to the positive electrode of the second energy storage filter capacitor.

3. The switching power supply circuit with undervoltage protection according to claim 1, characterized in that: An RCD absorption circuit is also provided between the primary coil and the input undervoltage protection circuit, and the RCD absorption circuit comprises: a second resistor, one end of the second resistor being coupled to the first end; a third resistor, the third resistor being connected in parallel with the second resistor; A first capacitor, wherein the first capacitor is connected in parallel with the third resistor; A first diode, wherein an anode of the first diode is coupled to the second end, and a cathode of the first diode is coupled to the other end of the second resistor.

4. The switching power supply circuit with undervoltage protection according to claim 1, characterized in that: The at least one secondary coil includes a first secondary coil, and the first secondary coil includes a third end and a fourth end; The feedback circuit comprises: An optical coupling transmission component, the optical coupling transmission component comprising a receiver and a transmitter; one end of the receiver is grounded through a fourth resistor, and the other end of the receiver is coupled to the feedback end; One end of the transmitter is coupled to the third end through a fifth resistor; A three-terminal parallel adjustable voltage regulator, wherein the negative electrode of the three-terminal parallel adjustable voltage regulator is grounded, and the positive electrode of the three-terminal parallel adjustable voltage regulator is coupled to the other end of the transmitter; A feedback voltage circuit, wherein an input terminal of the feedback voltage circuit is coupled to an output terminal of a first output circuit, a ground terminal of the feedback voltage circuit is grounded, and an output terminal of the feedback voltage circuit between the input terminal and the ground terminal is coupled to a reference terminal of the three-terminal parallel adjustable regulator to output a feedback voltage; A sixth resistor, one end of the sixth resistor is coupled to the fifth resistor, and the other end of the sixth resistor is coupled to the other end of the transmitter.

5. The switching power supply circuit with undervoltage protection according to claim 4, characterized in that: The feedback voltage circuit comprises: a seventh resistor, one end of the seventh resistor being coupled to the external load, and the other end of the seventh resistor being grounded through an eighth resistor; A connection point between the seventh resistor and the eighth resistor leads to an output end of the feedback voltage circuit.

6. The switching power supply circuit with undervoltage protection according to claim 4, characterized in that: The feedback circuit further includes a loop compensation circuit, and the loop compensation circuit includes: A second capacitor, one end of the second capacitor is coupled to the other end of the transmitter, and the other end of the second capacitor is coupled to the output end of the feedback voltage circuit through a ninth resistor.

7. The switching power supply circuit with undervoltage protection according to claim 4, characterized in that: The first output circuit comprises: a first output rectifier circuit, wherein an input terminal of the first output rectifier circuit is coupled to the third terminal; The output energy storage filter circuit comprises: a second inductor, one end of the second inductor is coupled to the output end of the first output rectifier circuit, and the other end of the second inductor is connected to the external load; a third energy storage filter capacitor, wherein a positive electrode of the third energy storage filter capacitor is coupled to one end of the second inductor, and a negative electrode of the third energy storage filter capacitor is grounded; a fourth energy storage filter capacitor, wherein a positive electrode of the fourth energy storage filter capacitor is coupled to the other end of the second inductor, and a negative electrode of the fourth energy storage filter capacitor is grounded; A third capacitor, wherein the third capacitor and the fourth energy storage filter capacitor are connected in parallel between the output terminal of the first output circuit and the ground terminal; A tenth resistor is connected in parallel with the third capacitor.

8. The switching power supply circuit with undervoltage protection according to claim 7, characterized in that: The first output rectifier circuit comprises: a second zener diode, wherein an anode of the second zener diode is coupled to the third end, and a cathode of the second zener diode is coupled to one end of the second inductor; An eleventh resistor, one end of the eleventh resistor is coupled to the anode of the second voltage-stabilizing diode, and the other end of the eleventh resistor is coupled to the cathode of the second voltage-stabilizing diode via a fourth capacitor.

9. The switching power supply circuit with undervoltage protection according to claim 1, characterized in that: The secondary coil includes a second secondary coil, and the second secondary coil includes a fifth end and a sixth end; The at least one output circuit comprises a second output circuit, an input terminal of the second output circuit is coupled to the second secondary coil; The second output circuit comprises: a third voltage stabilizing diode, wherein an anode of the third voltage stabilizing diode is coupled to the fifth end, and a cathode of the third voltage stabilizing diode is coupled to the external load; a fifth energy storage filter capacitor, wherein a positive electrode of the fifth energy storage filter capacitor is coupled to the fifth end, and a negative electrode of the fifth energy storage filter capacitor is grounded; A fifth capacitor, the fifth capacitor being connected in parallel with the fifth energy storage filter capacitor; A twelfth resistor is connected in parallel with the fifth capacitor.

10. A DC circuit breaker, characterized in that: It comprises a switching power supply circuit with undervoltage protection as described in any one of claims 1 to 9.

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