Power supply circuit and power supply system

Abstract

The utility model provides a power supply circuit and a power supply system, and relates to the technical field of power supply. The power supply circuit comprises a main power switch module, a main power filtering module, a main power rectification module, a first capacitor and a pre-charging branch circuit, the main power switch module and the pre-charging branch circuit are connected with a three-phase power grid, and the main power switch module, the main power filtering module, the main power rectification module and the first capacitor are connected in sequence. The main power filtering module comprises a plurality of second capacitors; the pre-charging branch is also connected with the first capacitors and the second capacitors; wherein in a standby state, the main power switch module and the pre-charging branch are both in a disconnected state; when the main power switch module is in a power-on state, the main power switch module is in a disconnected state, and the pre-charging branch is in a connected state, so that the first capacitor and the second capacitor are pre-charged; and in a normal power supply state, the main power switch module is in an on state, and the pre-charging branch is in an off state. The method has the advantage that the current impact is reduced.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a power supply circuit and a power supply system. Background Art

[0002] In the power supply circuit, in order to reduce reactive power consumption during standby mode, the connection between the power supply circuit and the main circuit can be cut off during standby mode.

[0003] However, when switching from the standby state to the normal operating state, a large current surge will be generated at the moment the main relay is closed due to the capacitance in the power supply circuit, shortening the service life of the main relay.

[0004] In summary, the prior art has the problem that the service life of the main relay is shortened due to current shock. Utility Model Content

[0005] The purpose of the present application is to provide a power supply circuit and a power supply system to solve the problem in the prior art that the service life of a main relay is shortened due to current shock.

[0006] In order to achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] On the one hand, an embodiment of the present application provides a power supply circuit, which includes a main power switch module, a main power filter module, a main power rectifier module, a first capacitor and a pre-charge branch, wherein the main power switch module and the pre-charge branch are both connected to a three-phase power grid, the main power switch module, the main power filter module, the main power rectifier module and the first capacitor are connected in sequence, the main power filter module includes multiple second capacitors, and the pre-charge branch is also connected to the first capacitor and the second capacitor; wherein,

[0008] When in the standby state, the main power switch module and the pre-charge branch are both in the disconnected state;

[0009] When in a power-on state, the main power switch module is in a disconnected state, and the pre-charging branch is in a conductive state, so as to pre-charge the first capacitor and the second capacitor;

[0010] When in a normal power supply state, the main power switch module is in an on state, and the pre-charge branch is in an off state.

[0011] Optionally, the pre-charging branch includes a wake-up module, a first pre-charging module, a second pre-charging module and a pre-charging rectifier module. The input end of the wake-up module is connected to the three-phase power grid, and the output end of the wake-up module is respectively connected to the first pre-charging module and the second pre-charging module. The first pre-charging module is connected to the second capacitor, and the output end of the pre-charging rectifier module is connected to the first capacitor.

[0012] Optionally, the main power switch module includes at least two main power relays, the number of the pre-charging branches is the same as the number of the main power relays, and each main power relay and each pre-charging branch is connected to one phase of the three-phase power grid.

[0013] Optionally, the first pre-charging module includes a first pre-charging relay, and the wake-up module, the first pre-charging relay and the second capacitor are connected in sequence.

[0014] Optionally, the second pre-charging module includes a second current limiting resistor and a second pre-charging relay, and the wake-up module, the second current limiting resistor, the second pre-charging relay and the pre-charging rectifier module are connected in sequence.

[0015] Optionally, the second pre-charge module includes a second current limiting resistor, and the wake-up module, the second current limiting resistor and the pre-charge rectifier module are connected in sequence.

[0016] Optionally, the wake-up module includes a switch component and a third current-limiting resistor, the two ends of the switch component are respectively connected to the three-phase power grid and the third current-limiting resistor, and the third current-limiting resistor is also respectively connected to the first pre-charging module and the second pre-charging module.

[0017] Optionally, the pre-charging branch includes a fourth current limiting resistor, a first pre-charging module, a second pre-charging module and a pre-charging rectifier module, the input end of the fourth current limiting resistor is connected to the three-phase power grid, the output end of the fourth current limiting resistor is respectively connected to the first pre-charging module and the second pre-charging module, the first pre-charging module is connected to the second capacitor, the output end of the second pre-charging module is connected to the pre-charging rectifier module, and the output end of the pre-charging rectifier module is connected to the first capacitor.

[0018] Optionally, the second pre-charging module includes a wake-up relay and a second current limiting resistor, the two ends of the wake-up relay are respectively connected to the fourth current limiting resistor and the second current limiting resistor, and the second current limiting resistor is also connected to the pre-charging rectifier module.

[0019] On the other hand, an embodiment of the present application further provides a power supply system, which includes the above-mentioned power supply circuit.

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] The present application provides a power supply circuit and a power supply system, which includes a main power switch module, a main power filter module, a main power rectifier module, a first capacitor and a pre-charging branch. The main power switch module and the pre-charging branch are both connected to a three-phase power grid. The main power switch module, the main power filter module, the main power rectifier module and the first capacitor are connected in sequence. The main power filter module includes multiple second capacitors, and the pre-charging branch is also connected to the first capacitor and the second capacitor. When in standby state, the main power switch module and the pre-charging branch are both in a disconnected state. When in a power-on state, the main power switch module is in a disconnected state and the pre-charging branch is in a conducting state to pre-charge the first capacitor and the second capacitor. When in a normal power supply state, the main power switch module is in a conducting state and the pre-charging branch is in a disconnected state.

[0022] First, since the power supply circuit provided by the present application is in a standby state, the main power switch module and the pre-charge branch are both in a disconnected state, thereby reducing the reactive power consumption of the standby state as a whole. Second, when powered on, the main power switch module is not directly turned on, but first pre-charges the first capacitor and the second capacitor, thereby reducing the current impact on the main power switch module when switching from the standby state to the operating state. Third, during normal power supply, the entire pre-charge branch will be in a disconnected state, thereby preventing the performance of the entire main power filter module from declining, thereby improving the performance of the entire power supply circuit.

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is a first circuit diagram of a pre-charging circuit in the prior art.

[0026] Figure 2 This is a second circuit diagram of a pre-charging circuit in the prior art.

[0027] Figure 3 This is a third circuit diagram of a pre-charging circuit in the prior art.

[0028] Figure 4This is a fourth circuit diagram of a pre-charging circuit in the prior art.

[0029] Figure 5 A schematic diagram of a module of a power supply circuit provided in an embodiment of the present application.

[0030] Figure 6 This is a first circuit diagram of the power supply circuit provided in an embodiment of the present application.

[0031] Figure 7 A second circuit diagram of the power supply circuit provided in an embodiment of the present application.

[0032] Figure 8 This is a third circuit diagram of the power supply circuit provided in an embodiment of the present application.

[0033] Figure 9 This is a fourth circuit diagram of the power supply circuit provided in an embodiment of the present application.

[0034] Figure 10 This is a fifth circuit diagram of the power supply circuit provided in an embodiment of the present application.

[0035] In the picture:

[0036] 110 - main power switch module; 120 - main power filter module; 130 - main power rectifier module; 140 - first capacitor; 150 - pre-charge branch; 151 - wake-up module; 152 - first pre-charge module; 153 - second pre-charge module; 154 - pre-charge rectifier module. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0039] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0040] It should be noted that, in this document, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0041] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0042] As described in the background art, in the prior art, when the power supply circuit switches from the standby state to the normal operating state, a large current shock is generated at the moment the main relay is energized, shortening the service life of the main relay.

[0043] In order to avoid large current shocks, the capacitors in the circuit are usually pre-charged before the circuit operates. Figure 1-Figure 4 As shown in FIG, it is a pre-charge circuit in the prior art. Figure 1 In the figure, K10 and K11 represent the main power relays, R10 and R11 represent pre-charge resistors, C10-C15 represent filter capacitors, and L10-L12 represent filter inductors. The main power rectifier circuit is used to rectify the AC power from the three-phase power grid into DC power. C16 represents the DC bus capacitor, and R15 represents the DC bus resistor. When the circuit is in standby mode, the main power relays K10 and K11 are disconnected. At this time, the circuit pre-charges the filter capacitors C10-C15 through pre-charge resistors R10 and R11. Although this pre-charge method can avoid the large current surge generated when the main relay is closed, the circuit is continuously in the on state, resulting in higher power consumption for the entire circuit.

[0044] The three-phase power grid includes phase A, phase B and phase C. Figure 1 In the example, only the main power relays are set on phases A and C. Figure 2 , another pre-charging circuit diagram in the prior art is shown. In which, relays are provided on phases A, B and C, and correspondingly, a corresponding pre-charging resistor R12 is also provided on phase B to achieve pre-charging.

[0045] Figure 3 and Figure 1 The circuit is similar, the difference is that the position of the pre-charge resistor and the main power relay is changed, but the working principle is the same; Figure 4and Figure 2 The circuit is similar to the one in the previous example, the difference is that the positions of the pre-charging resistor and the main power relay are changed, but the working principle is the same.

[0046] It can be seen that in the prior art, after adding a pre-charging circuit, the pre-charging circuit still has a large amount of loss. In view of this, in order to solve the above problems, the present application provides a power supply circuit. The power supply circuit provided by the present application is exemplarily described below:

[0047] As an optional implementation, see Figure 5 The power supply circuit includes a main power switch module 110, a main power filter module 120, a main power rectifier module 130, a first capacitor 140 and a pre-charging branch 150. The main power switch module 110 and the pre-charging branch 150 are all connected to the three-phase power grid. The main power switch module 110, the main power filter module 120, the main power rectifier module 130 and the first capacitor 140 are connected in sequence. The main power filter module 120 includes multiple second capacitors. The pre-charging branch 150 is also connected to the first capacitor 140 and the second capacitor. When in the standby state, the main power switch module 110 and the pre-charging branch 150 are both in the disconnected state. When in the power-on state, the main power switch module 110 is in the disconnected state and the pre-charging branch 150 is in the conductive state to pre-charge the first capacitor 140 and the second capacitor. When in the normal power supply state, the main power switch module 110 is in the conductive state and the pre-charging branch 150 is in the disconnected state.

[0048] It can be understood that, on the one hand, since the power supply circuit provided by the present application is in the standby state, the main power switch module 110 and the pre-charge branch 150 are both in the disconnected state, the reactive power consumption of the standby state is reduced as a whole. On the other hand, when powered on, the main power switch module 110 is not directly turned on, but first pre-charges the first capacitor 140 and the second capacitor, thereby reducing the current impact on the main power switch module 110 when switching from the standby state to the operating state. On the third hand, during normal power supply, the entire pre-charge branch 150 will be in the disconnected state again, thereby preventing the performance of the entire main power filter module 120 from declining, thereby improving the performance of the entire power supply circuit.

[0049] The second capacitor provided in this application can be an X capacitor, and the first capacitor 140 can be an ordinary capacitor. Of course, in some other implementations, the second capacitor can also be other types of capacitors, which are not limited here. When the second capacitor is an X capacitor, if in standby mode, the main power circuit is still connected to the three-phase power grid, the AC input X capacitor will generate a large amount of reactive power consumption, and the first capacitor 140 will also have power consumption. Therefore, by providing the main power switch module 110, the connection between the power supply circuit and the three-phase power grid can be disconnected in the standby mode, thereby significantly reducing the reactive power consumption of the circuit.

[0050] like Figure 5 As shown, as an implementation method, the pre-charging branch 150 includes a wake-up module 151, a first pre-charging module 152, a second pre-charging module 153 and a pre-charging rectifier module 154. The input end of the wake-up module 151 is connected to the three-phase power grid, and the output end of the wake-up module 151 is respectively connected to the first pre-charging module 152 and the second pre-charging module 153, the first pre-charging module 152 is connected to the second capacitor, and the output end of the pre-charging rectifier module 154 is connected to the first capacitor 140.

[0051] Among them, the wake-up module 151 is connected to the external control circuit, and when the wake-up module 151 needs to be turned on, the external control circuit can control the wake-up module 151 to be directly turned on. For example, when the user needs to use the power supply circuit to power the back-end load, the wake-up module 151 can be controlled to be turned on by the external control circuit. After the wake-up module 151 is turned on, the internal control circuit can continue to control the first pre-charge module 152 and / or the second pre-charge module 153 to be turned on, thereby pre-charging the corresponding capacitors.

[0052] This application does not limit the specific circuits of the main power switch module 110 and the wake-up module 151. In one implementation, the main power switch module 110 includes at least two main power relays, the number of pre-charge branches 150 is the same as the number of main power relays, and each main power relay and each pre-charge branch 150 is connected to one phase of the three-phase power grid.

[0053] For example, see Figure 6 When the main power switch module 110 includes two main power relays, if the two main power relays are respectively connected to phases A and C of the three-phase power grid, then the number of pre-charging branches 150 is also two, and the two pre-charging branches 150 are respectively connected to phases A and C. When the main power switch module 110 includes three main power relays, and the three main power relays are respectively connected to phases A, B, and C of the three-phase power grid, then the number of pre-charging branches 150 is also three, and the three pre-charging branches 150 are respectively connected to phases A, B, and C.

[0054] In one implementation, the wake-up module 151 includes a switch component and a third current-limiting resistor, the two ends of the switch component are connected to the three-phase power grid and the third current-limiting resistor respectively, and the third current-limiting resistor is also connected to the first pre-charge module 152 and the second pre-charge module 153 respectively. It can be understood that when the number of pre-charge branches 150 is also two, the number of switch components and third current-limiting resistors is also two, and each switch component and a third current-limiting resistor form one pre-charge branch 150. Figure 6 For example, the switch assembly includes two pre-charging relays, namely K3 and K4, and two third current limiting resistors, namely R1 and R2. R1 and K3 are connected in series to form one pre-charging branch, and R2 and K4 are connected in series to form another pre-charging branch.

[0055] Meanwhile, the first pre-charge module 152 may include a first current limiting resistor ( Figure 6 The first pre-charge relay (not shown) is connected to the wake-up module 151, the first current-limiting resistor, the first pre-charge relay, and the second capacitor in sequence. Of course, the first pre-charge module 152 may also include only the first pre-charge relay. On this basis, the wake-up module, the first pre-charge relay, and the second capacitor are connected in sequence. The second pre-charge module 153 includes a second current-limiting resistor and a second pre-charge relay. The wake-up module 151, the second current-limiting resistor, the second pre-charge relay, and the pre-charge rectifier module 154 are connected in sequence.

[0056] Among them, the first pre-charge relay includes K5 and K6, the second pre-charge relay includes K7 and K8, the second pre-charge resistor includes R3 and R4, and in this application, the first pre-charge relay adopts a normally open relay, and the second pre-charge relay adopts a normally closed relay. The main power filter module 120 includes inductors L1-L3 and second capacitors C1-C6, and the second capacitors C1 and C4 are connected to phase A, the second capacitors C2 and C5 are connected to phase B, and the second capacitors C3 and C6 are connected to phase C. The pre-charge rectifier module 154 includes a rectifier bridge. In Figure 6 Based on the circuit working principle:

[0057] When the circuit is in standby state, the main power relays K1 and K2 are disconnected, and the wake-up relays K3 and K4 also remain disconnected, so the entire circuit does not generate standby power consumption.

[0058] When the circuit is awakened and powered on, for example, by a user, the wake-up relays K3 and K4 close. Since the second pre-charge relays K7 and K8 are normally closed, the pre-charge branch 150, after rectification by the pre-charge rectifier module 154, charges the first capacitor 140 at the rear end. When the first capacitor 140 is fully charged (for example, the completion of charging of the first capacitor 140 can be determined based on the charging time or the amount of charge stored in the first capacitor 140), the first pre-charge relays K5 and K6 can be closed, thereby pre-charging the second capacitors C1-C6.

[0059] After the second capacitor is pre-charged (for example, after a delay, it is confirmed that the second capacitor is pre-charged), the main power relays K1 and K2 can be closed to achieve normal power supply of the circuit. At the same time, in order to prevent the performance of the entire main power filter module 120 from being degraded and improve the performance of the entire power supply circuit, the wake-up relays K3 and K4 can be synchronously controlled to be disconnected, and the first pre-charge relays K5 and K6, and the second pre-charge relays K7 and K8 can be reset. Specifically, when the synchronously controlled wake-up relays K3 and K4 are disconnected, it is equivalent to disconnecting the pre-charge branch, thereby ensuring that the common-mode filtering performance of the filter in the main power circuit is not degraded.

[0060] When the entire power supply circuit needs to be shut down, the main power relays K1 and K2 are controlled to be disconnected.

[0061] exist Figure 6 Based on the circuit shown, see Figure 7 The second pre-charging module 153 may also include only the second pre-charging relay without the second current limiting resistor. Alternatively, refer to Figure 8 The second pre-charging module 153 may also only include a second current limiting resistor without including a second pre-charging relay.

[0062] In another implementation, see Figure 9 , the wake-up module 151 may also include only a switch component, and in this case the first pre-charge module 152 includes a first current limiting resistor and a first pre-charge relay, which can effectively pre-charge the second capacitor. Figure 9 As shown, the first current limiting resistor includes R1 and R2, R1 is connected to the first pre-charging relay K5, and R2 is connected to the first pre-charging relay K6, to ensure that there are current limiting resistors in the branches for pre-charging the first capacitor 140 and the second capacitor.

[0063] In another implementation, see Figure 10The pre-charging branch 150 includes a fourth current limiting resistor, a first pre-charging module 152, a second pre-charging module 153 and a pre-charging rectifier module 154. The input end of the fourth current limiting resistor is connected to the three-phase power grid, and the output end of the fourth current limiting resistor is respectively connected to the first pre-charging module 152 and the second pre-charging module 153. The first pre-charging module 152 is connected to the second capacitor, the output end of the second pre-charging module 153 is connected to the pre-charging rectifier module 154, and the output end of the pre-charging rectifier module 154 is connected to the first capacitor 140.

[0064] Among them, the second pre-charging module 153 includes a wake-up relay and a second current limiting resistor. The two ends of the wake-up relay are respectively connected to the fourth current limiting resistor and the second current limiting resistor. The second current limiting resistor is also connected to the pre-charging rectifier module 154. Figure 10 In the embodiment, the wake-up relay K3 is connected to the second current-limiting resistor R3, and the wake-up relay K4 is connected to the second current-limiting resistor R4.

[0065] That is, in this implementation, after the wake-up relay is turned on, the first capacitor 140 is directly precharged. When the second capacitor needs to be precharged, the first precharge relays K5 and K6 are turned on.

[0066] Of course, when the number of main power switch tubes is 3, the number of pre-charging branches 150 is 3, and each pre-charging branch 150 is connected to one phase of the three-phase power grid.

[0067] Based on the above implementation, an embodiment of the present application further provides a power supply system, which includes the above power supply circuit.

[0068] In summary, the present application provides a power supply circuit and power supply system, which includes a main power switch module, a main power filter module, a main power rectifier module, a first capacitor and a pre-charge branch. The main power switch module and the pre-charge branch are all connected to the three-phase power grid, and the main power switch module, the main power filter module, the main power rectifier module and the first capacitor are connected in sequence. The main power filter module includes multiple second capacitors, and the pre-charge branch is also connected to the first capacitor and the second capacitor. When in standby mode, the main power switch module and the pre-charge branch are both in a disconnected state. When in power-on mode, the main power switch module is in a disconnected state, and the pre-charge branch is in a conducting state to pre-charge the first capacitor and the second capacitor. When in normal power supply mode, the main power switch module is in a conducting state, and the pre-charge branch is in a disconnected state. On the one hand, since the power supply circuit provided by the present application is in a standby state, the main power switch module and the pre-charge branch are both in a disconnected state, the reactive power consumption of the standby mode is reduced as a whole. Secondly, when powered on, the main power switch module does not turn on directly. Instead, it pre-charges the first and second capacitors, reducing the current impact on the main power switch module when switching from standby to operation. Thirdly, during normal power supply, the entire pre-charge branch is disconnected, which prevents the performance of the entire main power filter module from being degraded, thereby improving the performance of the entire power supply circuit.

[0069] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0070] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A power supply circuit, characterized in that: The power supply circuit includes a main power switch module, a main power filter module, a main power rectifier module, a first capacitor and a pre-charge branch. The main power switch module and the pre-charge branch are both connected to a three-phase power grid. The main power switch module, the main power filter module, the main power rectifier module and the first capacitor are connected in sequence. The main power filter module includes multiple second capacitors. The pre-charge branch is also connected to the first capacitor and the second capacitor. When in the standby state, the main power switch module and the pre-charge branch are both in the disconnected state; When in a power-on state, the main power switch module is in a disconnected state, and the pre-charging branch is in a conductive state, so as to pre-charge the first capacitor and the second capacitor; When in a normal power supply state, the main power switch module is in an on state, and the pre-charge branch is in an off state.

2. The power supply circuit according to claim 1, wherein: The pre-charging branch includes a wake-up module, a first pre-charging module, a second pre-charging module and a pre-charging rectifier module. The input end of the wake-up module is connected to the three-phase power grid, and the output end of the wake-up module is respectively connected to the first pre-charging module and the second pre-charging module. The first pre-charging module is connected to the second capacitor, and the output end of the pre-charging rectifier module is connected to the first capacitor.

3. The power supply circuit according to claim 2, wherein: The main power switch module includes at least two main power relays. The number of the pre-charging branches is the same as the number of the main power relays. Each of the main power relays and each pre-charging branch is connected to one phase of the three-phase power grid.

4. The power supply circuit according to claim 2, wherein: The first pre-charging module includes a first pre-charging relay, and the wake-up module, the first pre-charging relay and the second capacitor are connected in sequence.

5. The power supply circuit according to claim 2, wherein: The second pre-charging module includes a second current limiting resistor and a second pre-charging relay, and the wake-up module, the second current limiting resistor, the second pre-charging relay and the pre-charging rectifier module are connected in sequence.

6. The power supply circuit according to claim 2, wherein: The second pre-charge module includes a second current limiting resistor, and the wake-up module, the second current limiting resistor and the pre-charge rectifier module are connected in sequence.

7. The power supply circuit according to any one of claims 2 to 6, characterized in that: The wake-up module includes a switch component and a third current-limiting resistor. The two ends of the switch component are respectively connected to the three-phase power grid and the third current-limiting resistor. The third current-limiting resistor is also respectively connected to the first pre-charging module and the second pre-charging module.

8. The power supply circuit according to claim 1, wherein: The pre-charging branch includes a fourth current limiting resistor, a first pre-charging module, a second pre-charging module and a pre-charging rectifier module. The input end of the fourth current limiting resistor is connected to the three-phase power grid, and the output end of the fourth current limiting resistor is respectively connected to the first pre-charging module and the second pre-charging module. The first pre-charging module is connected to the second capacitor, the output end of the second pre-charging module is connected to the pre-charging rectifier module, and the output end of the pre-charging rectifier module is connected to the first capacitor.

9. The power supply circuit according to claim 8, wherein: The second pre-charging module includes a wake-up relay and a second current-limiting resistor. The two ends of the wake-up relay are respectively connected to the fourth current-limiting resistor and the second current-limiting resistor. The second current-limiting resistor is also connected to the pre-charging rectifier module.

10. A power supply system, characterized in that: The power supply system comprises the power supply circuit according to any one of claims 1 to 9.

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