Anti-surge circuit module and switching power supply

Abstract

The invention provides an anti-surge circuit module and a switching power supply. The anti-surge circuit module provided by the invention comprises a lightning protection circuit, a rectification circuit and a PFC circuit, the PFC circuit comprises a PFC unit and a surge shunting unit, and the surge shunting unit shunts surge current applied to the PFC unit by a power supply. The impedance corresponding to the surge shunting unit and the inductance value of the inductance element in the PFC unit have a direct proportion relationship, so that the impedance corresponding to the surge shunting unit is beneficial to matching the surge shunting requirement of the inductance element in the PFC unit, and the shunting of the surge current passing through a follow current switch tube in the PFC unit and the surge current passing through a bus capacitor are balanced; damage to a follow current switch tube in the anti-surge circuit module and components in a post-stage circuit can be avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a surge protection circuit module and a switching power supply. Background Technology

[0002] In switching power supplies, adding a bypass diode to the power factor correction (PFC) circuit can prevent component damage during surges (such as lightning strikes). However, for switching power supplies with high switching frequencies, excessive current shunting in the PFC circuit can still occur, leading to damage to the switching transistors. Summary of the Invention

[0003] This application provides a surge protection circuit module and a switching power supply, which enables the impedance of the surge protection circuit module and the PFC circuit in the switching power supply to match the surge current shunting requirements, thereby helping to avoid damage to the components in the surge protection circuit module and the switching power supply in the event of a surge.

[0004] In a first aspect, this application provides a surge protection circuit module, which includes a lightning protection circuit, a rectifier circuit, and a power factor correction (PFC) circuit. The PFC circuit includes a PFC unit and a surge shunt unit, which are connected in parallel. The PFC unit is used to perform power factor correction on the power supply output of the rectifier circuit. The surge shunt unit is used to shunt the surge current applied to the PFC unit by the power supply. The impedance of the surge shunt unit is directly proportional to the inductance of the inductor in the PFC unit. The two input terminals of the rectifier circuit are connected to the L-line output terminal and the N-line output terminal of the lightning protection circuit, respectively. The L-line output terminal of the rectifier circuit is connected to the first input terminal of the PFC circuit, and the N-line output terminal of the rectifier circuit is connected to the second input terminal of the PFC circuit.

[0005] When there is a direct proportional relationship between the impedance of the surge shunt unit and the inductance of the inductor in the PFC unit, it is beneficial for the impedance of the surge shunt unit to match the surge shunt requirements of the inductor in the PFC unit, balance the surge current shunt through the freewheeling switch in the PFC unit and the surge current through the bus capacitor, and help avoid damage to the freewheeling switch in the surge protection circuit module and the components in the subsequent circuit.

[0006] In some implementations, the surge shunt unit includes a unidirectional conducting element and an inductive element. The unidirectional conducting element is used to receive power from the first input terminal of the PFC circuit, and the inductance of the inductive element is directly proportional to the inductance of the inductive element in the PFC unit.

[0007] The inductive element in the surge shunt unit can store and release energy, and has a strong surge current shunt carrying capacity, which helps to reduce the possibility of damage to the surge shunt unit.

[0008] In some implementations, the inductive element includes at least one inductive element.

[0009] Inductors have good temperature stability, enabling them to maintain stable impedance even when surges cause temperature rise, thus helping to improve the power supply stability of surge protection circuit modules.

[0010] In some implementations, the inductor is a wire-wound inductor on a printed circuit board (PCB).

[0011] The inductance of a wire-wound inductor can be flexibly adjusted by changing the number of turns and the wire diameter. This is beneficial for matching the surge shunt requirements of the inductor in the impedance matching PFC unit corresponding to the surge shunt unit, and helps to avoid damage to the freewheeling switch in the surge protection circuit module and components in the subsequent circuit.

[0012] In some implementations, the input terminal of the unidirectional conducting element is connected to the L-line input terminal of the PFC unit, the output terminal of the unidirectional conducting element is connected to one end of the inductive element, and the other end of the inductive element is connected to the L-line output terminal of the PFC unit.

[0013] In some implementations, one end of the inductive element is connected to the L-line input of the PFC unit, the other end of the inductive element is connected to the input of the unidirectional conducting element, and the output of the unidirectional conducting element is connected to the L-line output of the PFC unit.

[0014] In some implementations, the rectifier circuit is a rectifier bridge consisting of four diodes.

[0015] In the surge protection circuit module, a rectifier bridge is used as the rectifier circuit. The rectifier bridge can provide full-wave rectification function using the entire cycle of the AC signal, thereby improving the efficiency of energy conversion.

[0016] In some implementations, the surge protection circuit includes a first inductor, a second inductor, a first capacitor, a second capacitor, and a resistive element; wherein, the L-line input terminal of the surge protection circuit is connected to the first terminal of the first inductor, the first terminal of the first capacitor, and the first terminal of the resistive element; the N-line input terminal of the surge protection circuit is connected to the first terminal of the second inductor, the second terminal of the first capacitor, and the second terminal of the resistive element; the second terminal of the first inductor is connected to the first terminal of the second capacitor and the L-line output terminal of the surge protection circuit; and the second terminal of the second capacitor is connected to the second terminal of the second inductor and the N-line output terminal of the surge protection circuit.

[0017] In the surge protection circuit module, the lightning protection circuit is placed before the PFC circuit. In the event of a surge, the surge current first passes through the lightning protection circuit, where most of the surge energy is consumed, which helps to prevent damage to the components in the PFC circuit and subsequent circuits.

[0018] In some implementations, the above resistive element includes a thermistor.

[0019] When a thermistor suppresses surge current, its temperature rises, which increases its resistance, thus improving the surge current suppression effect of the lightning protection circuit.

[0020] Secondly, this application provides a switching power supply, which includes a surge protection circuit module and a series resonant converter LLC circuit as described in the first aspect and any possible implementation of the first aspect.

[0021] The surge protection circuit module in the switching power supply can balance the surge current shunted through the freewheeling switch in the PFC unit and the surge current through the bus capacitor, which helps to avoid damage to the switching transistor on the primary side of the subsequent LLC circuit. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the topology of a boost PFC circuit in a switching power supply.

[0023] Figure 2 This is a schematic diagram of the topology of another switching power supply involving the boost PFC circuit.

[0024] Figure 3 This is a schematic diagram of the structure of a surge protection circuit module provided in one embodiment of this application;

[0025] Figure 4 A schematic diagram of the structure of a surge protection circuit module involving a PFC unit provided in one embodiment of this application;

[0026] Figure 5 A schematic diagram of the surge protection circuit module provided in one embodiment of this application, involving a surge shunt unit;

[0027] Figure 6 A schematic diagram of the surge protection circuit module provided in one embodiment of this application, involving a surge shunt unit;

[0028] Figure 7 A schematic diagram of the rectifier circuit structure of a surge protection circuit module provided in one embodiment of this application;

[0029] Figure 8 A schematic diagram of the structure of a surge protection circuit module related to a lightning protection circuit is provided in one embodiment of this application;

[0030] Figure 9 This is a schematic diagram of the structure of a switching power supply provided in one embodiment of this application;

[0031] Figure 10 This is a schematic diagram of the structure of a switching power supply provided in one embodiment of this application;

[0032] Figure 11 This is a schematic diagram of a charging device provided in one embodiment of this application. Detailed Implementation

[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0034] It should be understood that in the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship, but it does not exclude the possibility of indicating that the preceding and following related objects are in an "and" relationship. The specific meaning can be understood in conjunction with the context. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c; a and b; a and c; b and c; or a and b and c. Here, a, b, and c can be single or multiple.

[0035] In this embodiment of the application, the use of prefixes such as "first" and "second" is merely for the purpose of distinguishing and describing different things belonging to the same name category, and does not constrain the order, size, or quantity of things. For example, "first parameter" and "second parameter" are simply different parameters, and there is no temporal or quantitative relationship between them.

[0036] Furthermore, in the embodiments of this application, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as an "example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the term "example" is intended to present concepts in a concrete manner. In the embodiments of this application, "of," "corresponding, relevant," and "corresponding" may sometimes be used interchangeably, and it should be noted that their intended meanings are consistent unless their distinction is emphasized.

[0037] In the embodiments of this application, unless otherwise explicitly specified or limited, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific implementation.

[0038] A surge, also known as a transient or sudden event, is a peak value that appears instantaneously beyond the steady-state range. It includes surge voltage and surge current. Essentially, a surge is a violent pulse that occurs within an extremely short time, with its voltage peak potentially rising rapidly from hundreds of volts to tens of thousands of volts, and its current peak potentially reaching extremely high values. Lightning strikes are a typical example of a surge phenomenon.

[0039] In the field of switching power supplies, a certain level of surge protection is typically required to ensure normal operation under surge conditions. This includes a boost power factor correction (PFC) circuit. Currently, by adding bypass diodes and negative temperature coefficient (NTC) thermistors to the boost PFC circuit, surge current can be diverted to the bus capacitor, thereby reducing surge current shunting in the PFC circuit and preventing damage to components due to overcurrent.

[0040] Figure 1 This is a schematic diagram of the topology of a boost PFC circuit in a switching power supply. Figure 1As shown, inductor L1, switch S1, and switch S2 constitute a boost PFC circuit. One end of inductor L1 is used for input power supply, and the other end of inductor L1 is connected to the first end of switch S1 and the first end of switch S2. The second end of switch S1 is connected to one end of bus capacitor C1, and the second end of switch S2 is connected to the other end of bus capacitor C1. That is, the output terminal of the boost PFC circuit is connected in parallel with bus capacitor C1.

[0041] A diode D and a resistor R connected in series form a bypass circuit. In the bypass circuit, the anode of diode D is connected to one end of the inductor L, the cathode of diode D is connected to the first end of the NTC thermistor R, and the second end of the NTC thermistor R is connected to the second end of the switching transistor S1 and one end of the bus capacitor C1. That is, the boost PFC circuit and the bypass circuit are connected in parallel.

[0042] When the boost PFC circuit is working, if the input power supply generates an inrush current, the inrush current can be diverted by the above bypass circuit to reduce the inrush current input to the boost PFC circuit and reduce the possibility of damage to the freewheeling switch S1 due to excessive inrush current.

[0043] In a switching power supply, one switching cycle of the switching transistor includes one turn-on and one turn-off. For switching power supplies with high switching frequencies, the energy that the inductor needs to store in one switching cycle is reduced. Therefore, inductors with a smaller number of turns can be selected in the boost PFC circuit of the switching power supply.

[0044] The inductance of an inductor is related to the number of turns in the inductor coil. All other things being equal, the fewer the turns in the inductor coil, the smaller the inductance value. Using the inductor impedance formula Z = jωL, where Z is the inductor impedance, j is the imaginary unit, ω is the frequency of the alternating current, and L is the inductance, when the frequency ω of the alternating current is constant, the smaller the inductance L, the smaller the impedance Z of the inductor.

[0045] Therefore when Figure 1 When the number of turns of the inductor L1 in the boost PFC circuit of the switching power supply shown is reduced, the impedance Z of the inductor L1 decreases accordingly, which means that the current-blocking effect in the boost PFC circuit is weakened. Correspondingly, if the input power supply generates inrush current, the inrush current input to the boost PFC circuit will increase, which may damage the freewheeling switch S1.

[0046] For example: in Figure 1In the boost PFC circuit shown, the initial inductor L1 has 40 turns and an inductance of 400 microhenries (μH). A lightning strike test was performed on the boost PFC circuit. The shunt current through inductor L1 in the boost PFC circuit was 0.2 kA, and the shunt current through the bypass circuit was 0.8 kA, for a total lightning strike current of 1 kA. The freewheeling switch S1 in the boost PFC circuit can handle a maximum current of 0.4 kA. The shunt current of 0.2 kA does not reach this limit; therefore, the boost PFC circuit can continue to operate normally during a surge.

[0047] The initial inductor L1 in the boost PFC circuit is replaced with another inductor L2, with the number of turns reduced to 20. The inductance of inductor L2 is 100uH. A lightning strike test is then performed on the replaced boost PFC circuit, assuming the same lightning strike test parameters. The lightning strike current shunted through inductor L2 in the boost PFC circuit is 0.5kA, and the lightning strike current shunted through the bypass circuit is 0.7kA, for a total lightning strike current of 1.2kA across the boost PFC circuit and the bypass circuit. This 0.5kA lightning strike current shunted exceeds the maximum current capacity of the freewheeling switch S1 (0.4kA), potentially damaging the freewheeling switch S1.

[0048] Currently, one solution is to remove Figure 1 The NTC thermistor in the bypass circuit shown. During a surge, due to the inductive element's resistance to the surge current, the impedance of the boost PFC circuit is greater, and the surge current is shunted higher through the bypass circuit, thereby reducing the surge current flowing through the freewheeling switch S1.

[0049] Figure 2 This is a schematic diagram of the topology of a different switching power supply involving a boost PFC circuit. (See diagram below.) Figure 2 As shown, in the boost PFC circuit, inductor L1 is an inductor L2 with a lower number of turns, and the rest are the same as... Figure 1 The boost PFC circuit is the same as that described above, so it will not be repeated here.

[0050] Different from Figure 1 , Figure 2 A bypass circuit is formed by a diode D. In the bypass circuit, the anode of diode D is connected to one end of the inductor L, and the cathode of diode D is connected to the second terminal of the switching transistor S1 and one end of the bus capacitor C1. The boost PFC circuit is connected in parallel with the bypass circuit.

[0051] like Figure 2As shown, the subsequent stage of the boost PFC circuit is a series resonant converter LLC circuit. The primary side of the LLC circuit includes switching transistors S3 and S4, inductor L3, transformer, and capacitor C2. Specifically, the first terminal of switching transistor S3 is connected to the second terminal of switching transistor S1, the cathode of diode D, and one end of bus capacitor C1. The second terminal of switching transistor S3 is connected to the first terminals of inductor L3 and switching transistor S4. The second terminal of inductor L3 is connected to the first terminal of the primary winding of the transformer. The second terminal of the primary winding of the transformer is connected to the first terminal of capacitor C2. The second terminal of capacitor C2 is connected to the second terminal of switching transistor S4, the other end of bus capacitor C1, and the second terminal of switching transistor S2.

[0052] exist Figure 2 In the topology shown, with a reduced number of turns in the inductor used in the boost PFC circuit and the bypass circuit consisting of only one diode D, compared to Figure 1 In the topology shown, the total impedance of the parallel-connected boost PFC circuit and bypass circuit is further reduced. Therefore, when a surge occurs, although the impedance of the boost PFC circuit is greater than that of the bypass circuit, reducing the surge current flowing through the freewheeling switch S1, the total surge current of the power supply input to the boost PFC circuit and bypass circuit actually increases.

[0053] When the total inrush current of the power supply input boost PFC circuit and bypass circuit increases, the inrush current of the input bus capacitor C1 also increases, causing the voltage of bus capacitor C1 to rise accordingly. Bus capacitor C1 may be damaged due to the large inrush current or high voltage generated by the surge. In addition, the increased voltage of bus capacitor C1 may also cause the voltage to exceed the upper limit of the withstand voltage of switching transistor S3 or S4 in the subsequent LLC circuit, resulting in the damage of switching transistor S3 or S4.

[0054] Combining the examples above, in Figure 2 In the boost PFC circuit shown, the inductor L2 has 20 turns and an inductance of 100μH. Using the same lightning strike test parameters as the previous example, a lightning strike test is performed on the boost PFC circuit. The shunt current through inductor L2 in the boost PFC circuit is 0.1kA. This shunt current of 0.1kA is lower than the upper limit of the freewheeling switch S1's current capacity of 0.4kA, thus preventing damage to the freewheeling switch S1.

[0055] However, at this point, the shunt current through the bypass circuit is 1.4kA, and the total lightning current through the boost PFC circuit and the bypass circuit is 1.5kA. Compared to the total lightning current of 1.2kA in the previous example, even after removing the NTC thermistor in the bypass circuit, the total lightning current through the boost PFC circuit and the bypass circuit actually increases. At this time, the lightning current to the input bus capacitor rises from 1.2kA to 1.5kA, and the voltage of the bus capacitor rises from 540 volts (V) to 600V. 600V exceeds the voltage limit of the switching transistors S3 or S4 in the LLC circuit, potentially damaging them.

[0056] To address the aforementioned technical problems, this application provides a surge protection circuit module and a switching power supply, enabling the impedance of the surge protection circuit module and the PFC circuit in the switching power supply to match the surge current shunting requirements, thus helping to prevent damage to the components in the surge protection circuit module and the switching power supply in the event of a surge.

[0057] The surge protection circuit module provided in this application includes a lightning protection circuit, a rectifier circuit, and a PFC circuit. The PFC circuit includes a surge shunt unit, the impedance of which is the impedance that meets the surge protection requirements of the surge protection circuit module. This can balance the surge current shunt through the freewheeling switch in the PFC circuit and the total surge current through the bus capacitor, which helps to avoid damage to the components in the surge protection circuit module.

[0058] Figure 3 This is a schematic diagram of the surge protection circuit module provided in one embodiment of this application. For example,... Figure 3 As shown, the surge protection circuit module includes a lightning protection circuit 310, a rectifier circuit 320, and a PFC circuit 330. The PFC circuit 330 includes a PFC unit 331 and a surge shunt unit 332, which are connected in parallel.

[0059] The two input terminals of the rectifier circuit 320 are connected to the live (L) line output terminal and the neutral (N) line output terminal of the surge protection circuit 310, respectively. The L line output terminal of the rectifier circuit 320 is connected to the first input terminal of the PFC circuit 330, and the N line output terminal of the rectifier circuit 320 is connected to the second input terminal of the PFC circuit 330.

[0060] Understandably, in the event of a surge, the surge voltage passes sequentially through the surge protection circuit 310, the rectifier circuit 320, and the PFC circuit 330. When the surge voltage enters the L / N line, its peak voltage enters the surge protection circuit 310. The surge protection circuit 310 is used to suppress surge voltage. After the peak voltage enters the surge protection circuit 310, most of the surge energy is consumed here. The surge protection circuit 310 inputs the consumed surge voltage into the rectifier circuit 320 through its L-line output terminal and N-line output terminal.

[0061] The rectifier circuit 320 is used to rectify the input AC power supply to output a power supply. The rectifier circuit 320 converts the input AC power into DC power, and outputs the converted DC power to the PFC circuit 330. The DC power output by the rectifier circuit 320 can be regarded as the power supply for the PFC circuit 330.

[0062] In the PFC circuit 330, the PFC unit 331 is used to perform power factor correction on the power supply output of the rectifier circuit 330. Power factor is an indicator of the conversion efficiency of the surge protection circuit module; a high power factor means that more electrical energy is effectively utilized and reactive power loss is reduced. The PFC unit 331 can improve the power factor by adjusting the input current waveform to synchronize it with the input voltage waveform.

[0063] As an example, such as Figure 4 As shown, the PFC unit 331 may include an inductor L1, a switch S1, a switch S2, and a capacitor C1. The switch S1 is the freewheeling switch in the PFC unit 331, and the capacitor C1 is the bus capacitor in the PFC unit 331.

[0064] In this circuit, the first end of inductor L1 is connected to the first input terminal of PFC circuit 330 and the input terminal of surge shunt unit 332. The second end of inductor L1 is connected to the first end of switch S1 and the first end of switch S2. The second end of switch S1 is connected to the first end of capacitor C1 and the output terminal of surge shunt unit 332. The second end of capacitor C1 is connected to the second end of switch S2.

[0065] The control terminals of switching transistors S1 and S2 are respectively connected to the control unit, and the control unit... Figure 4 Not shown in the diagram. When the switch S1 is turned on, the PFC unit 331 is in the working state; when the switch S1 is turned off, the PFC unit is in the energy storage state.

[0066] In some implementations, the switching transistor S1 in the PFC unit 331 can also be replaced by a diode. The anode of the diode is connected to the second terminal of the inductor and the first terminal of the switching transistor S2, and the cathode of the diode is connected to the first terminal of the capacitor C1 and the output terminal of the surge shunt unit 332. Similar to the switching transistor S1, the diode acts as a freewheeling current when the switching transistor S2 is turned off.

[0067] The surge shunt unit 332 is used to shunt the surge current applied to the PFC unit 331 by the power supply. The impedance of the surge shunt unit 332 is directly proportional to the inductance of the inductor in the PFC unit 331.

[0068] In the event of a surge, the power supply output by the rectifier circuit 320 applies a surge current to the PFC circuit 330. The PFC circuit 330 contains a surge shunt unit 332 and a PFC unit 331, and the impedance corresponding to the surge shunt unit 332 is directly proportional to the inductance of the inductor in the PFC unit 331.

[0069] Referring to the aforementioned inductor impedance formula Z=jωL, it can be seen that, under a constant AC frequency, the impedance of the inductor L1 in PFC unit 331 is directly proportional to the inductance of the inductor L1. Therefore, it can be concluded that there is a direct proportionality between the impedance of surge shunt unit 322 and the inductance of inductor L1 in PFC unit 331, meaning that there is also a direct proportionality between the impedance of surge shunt unit 322 and the impedance of inductor L1 in PFC unit 331.

[0070] Understandable, Figure 3 The surge diversion unit 332 in the illustrated embodiment can be compared to the above. Figure 2 The bypass circuit in the middle. Figure 2 The bypass circuit consists of only one diode D. The forward-biased diode has extremely low impedance, resulting in a low total impedance between the parallel-connected boost PFC circuit and the bypass circuit.

[0071] When there is a direct proportional relationship between the impedance of the surge shunt unit 332 and the impedance of the inductor L1 in the PFC unit 331, as the number of turns of the inductor L1 decreases, the impedance of the inductor L1 decreases accordingly. The impedance of the surge shunt unit 332 decreases proportionally to the impedance of the inductor L1, compared to... Figure 2 The boost PFC circuit and bypass circuit are connected in parallel. The PFC circuit 330 still has a certain impedance value, which can impede the surge current output by the power supply.

[0072] Combined with the surge protection circuit 310 arranged at the front of the surge protection circuit module, after being consumed by the surge protection circuit 310, the surge current applied to the PFC circuit 330 by the rectified output power supply of the rectifier circuit 320 decreases, that is, the total surge current through the bus capacitor C1 decreases. Correspondingly, the voltage on the bus capacitor C1 also decreases. When an LLC circuit is connected in the subsequent circuit of the PFC circuit 330, the switching transistor in the primary side of the LLC circuit can carry the voltage in the bus capacitor C1.

[0073] It is understandable that the impedance value corresponding to the surge shunt unit 332 is usually smaller than the impedance value of the inductor in the PFC unit 331. This indicates that the surge shunt unit 332 has a smaller resistance to surge current. When the surge current applied by the power supply flows to the PFC unit 331 and the surge shunt unit 332 respectively, the surge shunt unit 332 shunts the surge current applied by the power supply to the PFC unit 331, with the larger current value flowing to the surge shunt unit 332.

[0074] As described above, the PFC circuit 330, combined with the surge protection circuit 310, reduces the surge current applied to the PFC circuit 330 by the power supply. Under the condition of a certain surge current, more current value is diverted to the surge shunt unit 332, which means that the surge current flowing to the PFC unit 331 is reduced, so that the switching transistor S1 used for freewheeling in the PFC unit 331 can bear the surge current.

[0075] In this embodiment, there is a direct proportional relationship between the impedance corresponding to the surge shunt unit 332 and the inductance of the inductor in the PFC unit 331. This makes it possible for the impedance corresponding to the surge shunt unit 332 to match the surge shunt requirements of the inductor in the PFC unit 331, balancing the surge current shunt through the freewheeling switch in the PFC unit 331 and the surge current through the bus capacitor. This helps to avoid damage to the freewheeling switch in the surge protection circuit module and components in the subsequent circuit.

[0076] In the above embodiments, the surge shunt unit 332 provides an impedance that is proportional to the inductance of the inductor in the PFC unit 331, so as to shunt the surge current applied to the PFC unit 331 by the power supply.

[0077] In some implementations, such as Figure 5 As shown, the surge shunt unit 332 may include a unidirectional conducting element 501 and an inductive element 502, wherein the unidirectional conducting element 501 and the inductive element 502 are connected in series between the L-line input terminal and the L-line output terminal of the PFC unit 331.

[0078] The unidirectional conducting element 501 receives the power supply from the rectifier circuit 320 at the first input terminal of the PFC circuit 330. When the PFC circuit 330 is operating normally, the output voltage of the PFC unit 331 is higher than the power supply voltage. At this time, the unidirectional conducting element 501 is in a reverse cutoff state and will not affect the operation of the PFC unit 331. In the event of a surge, the surge current is shunt into the surge shunt unit 332, that is, the surge current flows into the unidirectional conducting element 501 and the inductive element 502.

[0079] In some implementations, Figure 5 The unidirectional conducting element 501 includes a diode D bypass In the event of a surge, the surge current voltage is higher than the output voltage of the PFC unit 331, and the diode D in the surge shunt unit 332... bypass Conduction.

[0080] In the surge shunt unit 332, the inductance of the inductive element 502 is directly proportional to the inductance of the inductor in the PFC unit 331. As described above, the impedance of the surge shunt unit 332 is directly proportional to the inductance of the inductor in the PFC unit 331. The surge shunt unit 332 includes a unidirectional conducting element 501 and an inductive element 502 connected in series. Therefore, it can be understood that the total impedance of the unidirectional conducting element 501 and the inductive element 502 connected in series is directly proportional to the inductance of the inductor in the PFC unit 331.

[0081] Among them, the impedance of the unidirectional conducting element 501 is extremely low and can be approximated as a short-circuit element. Therefore, the total impedance of the unidirectional conducting element 501 and the inductive element 502 connected in series is equivalent to the impedance of the inductive element 502. That is, there is a direct proportional relationship between the impedance of the inductive element 502 and the inductance of the inductor in the PFC unit 331. Considering that the impedance of the inductive element 502 is also directly proportional to the inductance of the inductive element 502, it can be determined that there is a direct proportional relationship between the inductance of the inductive element 502 and the inductor in the PFC unit.

[0082] For example: in Figure 5In the surge protection circuit module shown, the inductance of inductor L1 in PFC unit 331 is 400μH. An inductor with an impedance of 1 ohm (Ω) is selected as inductor 502 in surge shunt unit 332. The inductance of inductor 502 is 8μH. In this case, the impedance of surge shunt unit 332 can balance the surge current shunted through freewheeling switch 402 in PFC unit 331 and the surge current through bus capacitor 404. When the number of turns of inductor L1 decreases, its inductance decreases from 400μH to 100μH. In order to meet the shunting requirements of surge shunt unit 332 in the event of a surge, the required impedance of inductor 502 is proportionally reduced to 0.25Ω. Correspondingly, the inductance of inductor 502 decreases to 2μH.

[0083] As one possible implementation, such as Figure 5 As shown, the input terminal of the unidirectional conducting element 501 (corresponding to diode D) bypass The anode of the diode is connected to the L-line input terminal of the PFC unit 331, and the output terminal of the unidirectional conduction element 501 (corresponding to diode D) is connected to the L-line input terminal of the PFC unit 331. bypass The cathode is connected to the first end of the inductive element 502, and the second end of the inductive element 502 is connected to the L-line output terminal of the PFC unit 331.

[0084] Understandably, in the event of a surge, the surge current is shunted from diode D in surge shunt unit 332. bypass The anode flows in, and then from diode D bypass The current flows out from the cathode and then into the inductive element 502. Compared to a resistor, which limits the shunting of surge current by impeding the flow of current, the inductive element 502 limits the shunting of surge current by storing energy and resisting changes in current. Under the same conditions, because the inductive element 502 can store and release energy, it has a stronger ability to withstand surge current shunting and is less likely to be damaged when subjected to large surge current shunting.

[0085] In some implementations, such as Figure 6 As shown, the first terminal of the inductive element 502 is connected to the L-line input terminal of the PFC unit 331, and the second terminal of the inductive element 502 is connected to the input terminal of the unidirectional conducting element 501 (corresponding to diode D). bypass The anode of the diode is connected to the output terminal of the unidirectional conducting element 501 (corresponding to diode D). bypass The cathode is connected to the L-line output terminal of the PFC unit 331.

[0086] In other words, the unidirectional conducting element 501 and the inductive element 502 are not limited to... Figure 5 The connection method shown can also be used by interchangeing the positions of the unidirectional conducting element 501 and the inductive element 502, as shown in the diagram. Figure 6The connection method shown is not limited in this embodiment.

[0087] In some implementations, such as those mentioned above Figure 5 and Figure 6 As shown, the inductive element 502 may include at least one inductor. Exemplarily, the inductive element 502 may also include a resistor connected in series with the inductor, with the first end of the inductor corresponding to the first end of the inductive element 502, and the second end of the inductor connected to the first end of the resistor, corresponding to the second end of the inductive element 502. Alternatively, the inductive element 502 may also include an equivalent inductance that serves to store energy and resist current changes; this will not be elaborated further in this embodiment.

[0088] Understandably, inductors are typically made of heat-resistant materials such as copper wire and ferrite. These materials maintain good performance stability even at high temperatures and are not prone to performance changes due to temperature increases. In the event of a surge, when the surge current is shunt to the surge shunt unit 332, a large amount of heat is generated in a short time, causing the temperature of the inductor to rise. The inductor's good temperature stability allows it to maintain its function even under surge-induced temperature increases.

[0089] In some implementations, the inductor included in the above-mentioned inductive element 502 can specifically be a separate plug-in inductor. When the inductor is a plug-in inductor, the surge shunt unit 332 can flexibly select an inductor that can balance the surge current shunted through the freewheeling switch in the PFC circuit and the surge current through the bus capacitor, based on the inductance of the inductor in the PFC unit 331. This helps to reduce the difficulty of designing the surge protection circuit module.

[0090] In some implementations, the inductor included in the inductive element 502 can also be a wire-wound inductor on the PCB. A wire-wound inductor is an inductor device that uses wire wound around a magnetic core or frame. The inductance of a wire-wound inductor can be adjusted by changing parameters such as the number of turns and the wire diameter. As described above, the inductance of the inductive element 502 is directly proportional to the inductance of the inductor in the PFC unit 331. The wire-wound inductor can be flexibly adjusted by changing the number of turns or the wire diameter according to the change in the inductance of the inductor in the PFC unit 331, so that the inductance of the inductive element 502 matches the surge shunt unit 332's requirement to shunt surge current in the event of a surge.

[0091] It should be noted that the wire-wound inductor can be wound on a separate PCB board. When the wire-wound inductor is connected to the surge shunt unit 332, the separate PCB board with the inductor component can be connected to the PCB board where the surge protection circuit module is located.

[0092] Alternatively, the PCB motherboard for arranging surge protection circuit modules typically has a certain shape, with some unused spaces. Wires can be wound around these spaces to form wire-wound inductors that can match the shunting requirements of the surge shunt unit 332. Placing wire-wound inductors in the unused spaces on the PCB motherboard for surge protection circuit modules can make full use of the PCB motherboard space and reduce design and manufacturing costs.

[0093] The above embodiments focus on the topology of PFC unit 331 and surge shunt unit 332 in PFC circuit 330. The following further introduces rectifier circuit 320 and lightning protection circuit 310 in surge protection circuit module.

[0094] In some implementations, the rectifier circuit 320 can consist of an even number of diodes, with the L-line and N-line corresponding to an equal number of diodes. As an example, such as... Figure 7 As shown, the rectifier circuit 320 includes four diodes, and the rectifier circuit 320 is configured as a rectifier bridge composed of four diodes.

[0095] like Figure 7 As shown, the rectifier circuit 320 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anode of the first diode D1 is connected to the L-line output terminal of the surge protection circuit 310 and the cathode of the third diode D3. The cathode of the first diode D1 is connected to the first input terminal of the PFC circuit 330 and the cathode of the second diode D2. The anode of the second diode D2 is connected to the N-line output terminal of the surge protection circuit 310 and the anode of the fourth diode D4. The anode of the third diode D3 is connected to the second input terminal of the PFC circuit 330, and the anode of the fourth diode D4 is connected to the second input terminal of the PFC circuit 330.

[0096] It should be noted that the rectifier circuit 320 may also include a capacitor C2. The first end of capacitor C2 is connected to the L-line output terminal of the rectifier circuit 320, and the second end of capacitor C2 is connected to the N-line output terminal of the rectifier circuit 320. Capacitor C2 is equivalent to a filter capacitor installed across the rectifier circuit 320, used to reduce AC ripple and provide a high-efficiency and smooth DC power supply.

[0097] In some implementations, such as Figure 8 As shown, the surge protection circuit 310 may include a first inductor L2, a second inductor L3, a first capacitor C3, a second capacitor C4, and a resistor R.

[0098] The L-line input terminal of the surge protection circuit 310 is connected to the first terminal of the first inductor L2, the first terminal of the first capacitor C3, and the first terminal of the resistor R. The N-line input terminal of the surge protection circuit 310 is connected to the first terminal of the second inductor L3, the second terminal of the first capacitor C3, and the second terminal of the resistor R.

[0099] The second end of the first inductor L2 is connected to the first end of the second capacitor C4 and the L-line output terminal of the surge protection circuit 310. The second end of the second capacitor C4 is connected to the second end of the second inductor L3 and the N-line output terminal of the surge protection circuit 310.

[0100] In some implementations, the resistive element R may include a thermistor or a high-voltage resistor. It is understood that the resistive element R in the surge protection circuit 310 suppresses surge current. When suppressing surge current, the thermistor's temperature rises, thereby increasing its resistance and achieving a better surge current suppression effect. Surge currents are typically large, requiring the resistive element R to withstand high voltages. High-voltage resistors can withstand high voltages; therefore, the resistive element R may also include a high-voltage resistor.

[0101] Figure 9 This is a schematic diagram of a switching power supply provided in one embodiment of this application. Figure 9 As shown, corresponding to the above embodiments, the switching power supply may include a surge protection circuit module 910 and an LLC circuit 920.

[0102] The surge protection circuit module 910 includes a lightning protection circuit 911, a rectifier circuit 912, and a PFC circuit 913. The PFC circuit 913 includes a PFC unit 913-1 and a surge shunt unit 913-2, which are connected in parallel.

[0103] The structure of the surge protection circuit module 910 is the same as that of the surge protection circuit module provided in any of the aforementioned embodiments. The LLC circuit 920 is the subsequent circuit of the surge protection circuit module 910. The L-line input terminal of the LLC circuit 920 is connected to the L-line output terminal of the PFC circuit 913, and the N-line output terminal of the LLC circuit 920 is connected to the N-line output terminal of the PFC circuit 913.

[0104] As an example, such as Figure 10As shown, the primary side of the LLC circuit 920 includes switching transistors S3 and S4, inductor L4, transformer T, and capacitor C5. The first terminal of switching transistor S3 is connected to the L-line output terminal of the PFC circuit 913. The second terminal of switching transistor S3 is connected to the first terminals of inductor L4 and switching transistor S4. The second terminal of inductor L4 is connected to the first terminal of the primary winding of transformer T. The second terminal of the primary winding of transformer T is connected to the first terminal of capacitor C5. The second terminal of capacitor C5 is connected to the second terminal of switching transistor S4 and the N-line output terminal of the PFC circuit 913.

[0105] In the surge protection circuit module 910, there is a direct proportional relationship between the impedance of the surge shunt unit 913-2 and the inductance of the inductor in the PFC unit 913-1. This allows the impedance of the surge shunt unit 913-2 to match the surge shunt requirements of the inductor in the PFC unit 913-1, balancing the surge current shunted through the freewheeling switch in the PFC unit 913-1 and the surge current through the bus capacitor. This helps to prevent damage to the switching transistor on the primary side of the LLC circuit 920, which is used as a subsequent circuit.

[0106] Figure 11 This is a schematic diagram of a charging device provided in one embodiment of this application. Figure 11 As shown, the charging device 1100 includes an AC-DC power converter 1101, a DC-DC power converter 1102, and a DC bus 1103. The AC-DC power converter 1101 may include any of the surge protection circuit modules shown in the above embodiments.

[0107] The AC-DC power converter 1101 is used to convert the received AC power into DC power and output the converted DC power to the DC bus 1103. The DC-DC power converter 1102 is used to obtain DC power from the DC bus 1103 and output the DC power to the load after power conversion.

[0108] When the above-mentioned charging device 1100 is applied to a corresponding charging system, the charging device 1100 can convert the AC power output from the power grid into stable DC power to supply power to the load, such as providing charging services for electric vehicles.

[0109] It should be noted that the surge protection circuit module provided in this application embodiment can be applied to AC power supply, station power supply, on-board charger (OBC) and micro inverter scenarios, etc., and this application embodiment does not limit its specific application scenario.

[0110] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and intent of this application are indicated by the following claims.

[0111] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A surge protection circuit module, characterized in that, It includes a lightning protection circuit, a rectifier circuit, and a power factor correction (PFC) circuit. The PFC circuit includes a PFC unit and a surge shunt unit, with the PFC unit and the surge shunt unit connected in parallel. The PFC unit is used to perform power factor correction on the power supply output by the rectifier circuit. The surge shunt unit is used to shunt the surge current applied to the PFC unit by the power supply. The impedance of the surge shunt unit is directly proportional to the inductance of the inductor in the PFC unit. The two input terminals of the rectifier circuit are connected to the L-line output terminal and the N-line output terminal of the surge protection circuit, respectively. The L-line output terminal of the rectifier circuit is connected to the first input terminal of the PFC circuit, and the N-line output terminal of the rectifier circuit is connected to the second input terminal of the PFC circuit.

2. The module according to claim 1, characterized in that, The surge shunt unit includes a unidirectional conducting element and an inductive element. The unidirectional conducting element is used to receive the power supply from the first input terminal of the PFC circuit. The inductance of the inductive element is directly proportional to the inductance of the inductive element in the PFC unit.

3. The module according to claim 2, characterized in that, The inductive element includes at least one inductive element.

4. The module according to claim 3, characterized in that, The inductor is a wire-wound inductor on a printed circuit board (PCB).

5. The module according to any one of claims 2 to 4, characterized in that, The input terminal of the unidirectional conducting element is connected to the L-line input terminal of the PFC unit, the output terminal of the unidirectional conducting element is connected to one end of the inductive element, and the other end of the inductive element is connected to the L-line output terminal of the PFC unit.

6. The module according to any one of claims 2 to 4, characterized in that, One end of the inductive element is connected to the L-line input terminal of the PFC unit, the other end of the inductive element is connected to the input terminal of the unidirectional conducting element, and the output terminal of the unidirectional conducting element is connected to the L-line output terminal of the PFC unit.

7. The module according to any one of claims 1 to 6, characterized in that, The rectifier circuit is a rectifier bridge composed of four diodes.

8. The module according to any one of claims 1 to 7, characterized in that, The lightning protection circuit includes a first inductor, a second inductor, a first capacitor, a second capacitor, and a resistive element; Wherein, the L-line input terminal of the surge protection circuit is connected to the first terminal of the first inductor, the first terminal of the first capacitor and the first terminal of the resistor element, and the N-line input terminal of the surge protection circuit is connected to the first terminal of the second inductor, the second terminal of the first capacitor and the second terminal of the resistor element; The second end of the first inductor is connected to the first end of the second capacitor and the L-line output terminal of the surge protection circuit, and the second end of the second capacitor is connected to the second end of the second inductor and the N-line output terminal of the surge protection circuit.

9. The module according to claim 8, characterized in that, The resistive element includes a thermistor.

10. A switching power supply, characterized in that, It includes the surge protection circuit module and the series resonant converter LLC circuit as described in any one of claims 1 to 9.

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