Pre-charge circuit

Abstract

The invention provides a pre-charging circuit, and relates to the technical field of power electronics. The pre-charging circuit comprises a pre-charging control circuit, an electromagnetic interference module, a three-phase power supply module and a bus capacitor module, when the bus capacitor module is pre-charged, the first main relay, the second main relay and the second alternating current pre-charging module are disconnected, and the first direct current pre-charging module is connected; or, the first main relay is switched off, the second main relay is switched off, and the second direct current pre-charging module is switched on; when the electromagnetic interference module is pre-charged, the first main relay is switched on, the second main relay and the first alternating current pre-charging module are switched on, and the first direct current pre-charging module is switched off; or, the first main relay is switched on, and the second main relay and the second direct current pre-charging module are switched off. According to the application, the corresponding pre-charging loops are connected by separating the pre-charging paths and controlling the on-off of different relays, and the pre-charging of the alternating current capacitor and the pre-charging of the direct current bus capacitor are effectively decoupled from the circuit.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a pre-charging circuit. Background Art

[0002] In the design of the charging module of the existing charging pile, when the auxiliary power comes from the bus capacitor, the main relay is usually not closed in the standby state, so in order to maintain the standby working state of the pre-charging system, it is necessary to rely on the pre-charge capacitor to charge the bus capacitor. However, since the AC input and the DC bus are coupled together in the pre-charging circuit, that is, in the standby state, the pre-charge resistor not only bears the task of charging the bus capacitor, but also continues to be affected by the AC voltage, so that the pre-charge resistor is in a working state for a long time in the standby state, causing loss to the pre-charge resistor and generating unnecessary heat. The heat generated by the pre-charge resistor not only wastes energy, but may also cause aging and performance degradation of the resistor material, thereby affecting the reliability and life of the entire system. Summary of the invention

[0003] The purpose of the present application is to provide a pre-charging circuit to solve the problem of coupling between AC and DC pre-charging circuits in the prior art in view of the above-mentioned deficiencies in the prior art.

[0004] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows: The embodiment of the present application provides a pre-charging circuit, the pre-charging circuit comprising a pre-charging control circuit, an electromagnetic interference module, a three-phase power supply module and a bus capacitor module, the pre-charging control circuit comprising a three-phase branch, the three-phase branch comprising a first phase branch, a second phase branch and a third phase branch, and one end of each phase branch is respectively connected to one phase of the three-phase power supply module, and the other end of each phase branch is respectively connected to the bus capacitor module through the electromagnetic interference module; A first main relay and a first AC pre-charging module are provided on the first phase branch, and the first main relay is connected in parallel with the first AC pre-charging module, and the first AC pre-charging module includes a first AC pre-charging resistor and at least one first AC pre-charging relay; A second main relay is provided on the second phase branch, and the second main relay is connected in parallel with the second AC pre-charging module and the first DC pre-charging module, or the second main relay is connected in parallel with the second DC pre-charging module; When the bus capacitor module is precharged, the first main relay, the second main relay and the second AC precharge module are disconnected, and the first DC precharge module is turned on; or, the first main relay is disconnected, the second main relay is disconnected, and the second DC precharge module is turned on; When pre-charging the electromagnetic interference module, the first main relay is turned on, the second main relay and the first AC pre-charging module are turned on, and the first DC pre-charging module is disconnected; or, the first main relay is turned on, the second main relay and the second DC pre-charging module are disconnected.

[0005] As a possible implementation method, each of the first AC pre-charging relays in the first AC pre-charging module is connected in series, and one end of the first first AC pre-charging relay is connected to one end of the first main relay, the other end of the last first AC pre-charging relay is connected to one end of the first AC pre-charging resistor, and the other end of the first AC pre-charging resistor is connected to the other end of the first main relay.

[0006] As a possible implementation, the second AC pre-charging module includes: a second AC pre-charging resistor and at least one second AC pre-charging relay; Each of the second AC pre-charging relays is connected in series, and one end of the first second AC pre-charging relay is connected to one end of the second main relay, the other end of the last second AC pre-charging relay is connected to one end of the second AC pre-charging resistor, and the other end of the second AC pre-charging resistor is connected to the other end of the second main relay.

[0007] As a possible implementation, the first DC pre-charging module includes: a first DC pre-charging relay, a second DC pre-charging relay, a first DC pre-charging resistor, a second DC pre-charging resistor, a first DC pre-charging diode, and a second DC pre-charging diode.

[0008] As a possible implementation manner, the first DC pre-charging diode and the second DC pre-charging diode have the same conduction direction; One end of the first DC pre-charging relay is connected to one end of the second AC pre-charging relay, the other end of the first DC pre-charging relay is connected to one end of the first DC pre-charging resistor, and the other end of the first DC pre-charging resistor is connected to the other end of the second main relay; One end of the first DC pre-charging diode is connected to the other end of the second main relay, and the other end of the first DC pre-charging diode is connected to one end of the second DC pre-charging diode; One end of the second DC pre-charging relay is connected to one end of the first AC pre-charging relay, the other end of the second DC pre-charging relay is connected to one end of the second DC pre-charging resistor, and the other end of the second DC pre-charging resistor is connected to the other end of the second DC pre-charging diode.

[0009] As a possible implementation manner, the conduction directions of the first DC pre-charging diode and the second DC pre-charging diode are opposite; One end of the first DC pre-charging relay is connected to one end of the second AC pre-charging relay, the other end of the first DC pre-charging relay is connected to one end of the first DC pre-charging resistor, and the other end of the first DC pre-charging resistor is connected to the other end of the second main relay; One end of the first DC pre-charging diode is connected to the other end of the second main relay, and the other end of the first DC pre-charging diode is connected to one end of the bus capacitor module; One end of the second DC pre-charging relay is connected to one end of the first AC pre-charging relay, the other end of the second DC pre-charging relay is connected to one end of the second DC pre-charging resistor, the other end of the second DC pre-charging resistor is connected to one end of the second DC pre-charging diode, and the other end of the second DC pre-charging diode is connected to the other end of the bus capacitor module.

[0010] As a possible implementation, the second DC pre-charging module includes: a third DC pre-charging relay, a fourth DC pre-charging relay, a third DC pre-charging resistor, a third DC pre-charging diode and a fourth DC pre-charging diode; One end of the third DC pre-charging relay is connected to one end of the second main relay through the third AC pre-charging resistor, the other end of the third DC pre-charging relay is connected to one end of the fourth DC pre-charging relay, the other end of the fourth DC pre-charging relay is respectively connected to the other end of the second main relay and one end of the third DC pre-charging resistor, the other end of the third DC pre-charging resistor is connected to one end of the third DC pre-charging diode, the other end of the third DC pre-charging diode is connected to one end of the fourth DC pre-charging diode, and the other end of the fourth DC pre-charging diode is connected to one end of the bus capacitor module.

[0011] As a possible implementation method, one end of the third DC pre-charging relay is connected to one end of the second main relay, the other end of the third DC pre-charging relay is connected to one end of the fourth DC pre-charging relay, the other end of the fourth DC pre-charging relay is connected to the other end of the second main relay through a third AC pre-charging resistor, and the other end of the fourth DC pre-charging relay is connected to one end of the third DC pre-charging resistor, the other end of the third DC pre-charging resistor is connected to one end of the third DC pre-charging diode, the other end of the third DC pre-charging diode is connected to one end of the fourth DC pre-charging diode, and the other end of the fourth DC pre-charging diode is connected to one end of the bus capacitor module.

[0012] As a possible implementation manner, the electromagnetic interference module is connected to the bus capacitor module through an inductor and a bridge diode.

[0013] As a possible implementation, the pre-charging circuit further includes: a protection module; the protection module includes at least one varistor and at least one protection resistor; One end of the protection module is connected to the first DC pre-charging module or the second DC pre-charging module, and the other end of the protection module is connected to the electromagnetic interference module.

[0014] According to the pre-charging circuit of the embodiment of the present application, the pre-charging circuit includes a pre-charging control circuit, an electromagnetic interference module, a three-phase power supply module and a bus capacitor module, the pre-charging control circuit includes a three-phase branch, the three-phase branch includes a first phase branch, a second phase branch and a third phase branch, and one end of each phase branch is respectively connected to one phase of the three-phase power supply module, and the other end of each phase branch is respectively connected to the bus capacitor module through the electromagnetic interference module, a first main relay and a first AC pre-charging module are arranged on the first phase branch, and the first main relay is connected in parallel with the first AC pre-charging module, the first AC pre-charging module includes a first AC pre-charging resistor and at least one first AC pre-charging relay, a second main relay is arranged on the second phase branch, and the second main relay is connected in parallel with the second AC pre-charging module and the first DC pre-charging module, or the second main relay is connected in parallel with the second DC pre-charging module. On this basis, when the bus capacitor module is pre-charged, the first main relay, the second main relay and the second AC pre-charge module are disconnected, and the first DC pre-charge module is turned on; or, the first main relay is disconnected, the second main relay is disconnected, and the second DC pre-charge module is turned on, and when the electromagnetic interference module is pre-charged, the first main relay is turned on, the second main relay and the first AC pre-charge module are turned on, and the first DC pre-charge module is disconnected; or, the first main relay is turned on, the second main relay and the second DC pre-charge module are disconnected. It can be seen that the pre-charge circuit provided by the present application decouples the AC capacitor pre-charge and the DC bus capacitor pre-charge from the circuit, and connects the corresponding pre-charge circuit by separating the pre-charge path and controlling the on and off of different relays. Specifically, by controlling different relays, the corresponding pre-charge circuit is only connected when needed, and the corresponding circuit is kept disconnected when pre-charging is not required, so as to avoid unnecessary current flowing through the pre-charge resistor, and the pre-charge resistor will not generate power consumption and heat, thereby effectively solving the problem of damage caused by the pre-charge resistor being in the AC and DC circuits for a long time in the standby state. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of a pre-charging circuit provided in an embodiment of the present application is shown; Figure 2 A schematic diagram of a first AC pre-charging module provided in an embodiment of the present application is shown; Figure 3 A schematic diagram of a second AC pre-charging module provided in an embodiment of the present application is shown; Figure 4 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Figure 5 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Figure 6 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Figure 7 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Figure 8 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Fig. 9 A schematic diagram of another pre-charging circuit provided in an embodiment of the present application is shown; Fig.10 A flow chart of a pre-charging control method provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0017] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0018] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0019] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0020] In the prior art, the AC and DC pre-charging circuits are coupled together, causing the pre-charging resistor to heat up in the standby state. To address this issue, the present application provides a pre-charging circuit, which decouples the AC capacitor pre-charging and the DC bus capacitor pre-charging from the circuit, specifically by controlling the on and off of different relays to connect the corresponding pre-charging circuit, that is, by separating the pre-charging path, the loss of the pre-charging resistor caused by the AC current during the standby process is effectively reduced.

[0021] Figure 1 Schematic diagram of a pre-charging circuit provided in an embodiment of the present application is shown. Figure 1 As shown, the pre-charging circuit includes a pre-charging control circuit 10, an electromagnetic interference module 11 (Electromagnetic Interference, EMI), a three-phase power supply module 12 and a bus capacitor module 13. Among them, the pre-charging control circuit 10 includes a three-phase branch, the three-phase branch includes a first phase branch, a second phase branch and a third phase branch, and one end of each phase branch is respectively connected to one phase of the three-phase power supply module 12, and the other end of each phase branch is respectively connected to the bus capacitor module 13 through the electromagnetic interference module 11.

[0022] Optionally, refer to Figure 1 As shown, the first phase branch is the U phase branch, the second phase branch is the V phase branch, and the third phase branch is the W phase branch. The first phase branch is provided with a first main relay 101 and a first AC pre-charging module 102, and the first main relay 101 is connected in parallel with the first AC pre-charging module 102, and the first AC pre-charging module 102 includes a first AC pre-charging resistor R1 and at least one first AC pre-charging relay RlyPre1.

[0023] Optionally, a second main relay 103 is provided on the second phase branch, and the second main relay 103 is connected in parallel with the second AC pre-charging module 104 and the first DC pre-charging module 105, or the second main relay 103 is connected in parallel with the second DC pre-charging module. Figure 1 What is shown is a connection diagram in which the second main relay 103 is connected in parallel with the second AC pre-charging module 104 and the first DC pre-charging module 105, but the second main relay 103 can also be directly connected in parallel with the second DC pre-charging module, that is, the second AC pre-charging module 104 and the first DC pre-charging module 105 are replaced by the second DC pre-charging module.

[0024] Optionally, when pre-charging the bus capacitor module 13, the first main relay 101, the second main relay 103 and the second AC pre-charging module 104 are disconnected, and the first DC pre-charging module 105 is turned on; or, the first main relay 101 is disconnected, the second main relay 103 is disconnected, and the second DC pre-charging module is turned on.

[0025] Exemplarily, the electromagnetic interference module 11 is connected to the bus capacitor module 13 through an inductor and a bridge diode, and the bus capacitor module 13 includes a first capacitor and a second capacitor. When the bus capacitor module 13 is pre-charged, the charging circuit is composed of a bridge diode on the third phase branch (W phase branch) and a first DC pre-charge module 105, or a bridge diode on the third phase branch (W phase branch) and a second DC pre-charge module. In the standby state, the first main relay 101, the second main relay 103, the first AC pre-charge relay RlyPre1 in the first AC pre-charge module 102, and the second AC pre-charge relay RlyPre2 in the second AC pre-charge module 104 are all in a disconnected state, and the first DC pre-charge relay in the first DC pre-charge module 105 or the second DC pre-charge relay in the second DC pre-charge module is controlled by an external wake-up signal to close the charging circuit to form a charging circuit to charge the bus capacitor module 13. Furthermore, when the bus capacitor module 13 is charged until the line voltage reaches a preset value, which is, for example, the maximum line voltage, charging the bus capacitor module 13 is automatically stopped. At this time, the power consumption of the first AC pre-charging resistor R1 is 0, and accordingly, the heat generated by the first AC pre-charging resistor R1 is also very small, or even no heat is generated.

[0026] Optionally, when pre-charging the electromagnetic interference module 11, the first main relay 101 is turned on, the second main relay 103 and the first AC pre-charging module 102 are turned on, and the first DC pre-charging module 105 is disconnected; or, the first main relay 101 is turned on, the second main relay 103 and the second DC pre-charging module are disconnected.

[0027] Exemplarily, after the pre-charging of the busbar capacitor module 13 is completed, the first main relay and the second main relay must be closed to output the main power. At this time, in order to prevent the pressure difference between the two ends of the first main relay and the second main relay from being too large before being attracted, causing electric shock and ablation, the electromagnetic interference module 11 needs to be pre-charged, that is, the capacitor in the electromagnetic interference module 11 needs to be pre-charged. At this time, the charging circuit is composed of the first AC pre-charging relay RlyPre1, the first AC pre-charging resistor R1, the second AC pre-charging relay and the second AC pre-charging resistor in the second AC pre-charging module 104, and the capacitor in the electromagnetic interference module 11. The AC pre-charging is started by controlling the first AC pre-charging relay RlyPre1 and the second AC pre-charging relay. After the pre-charging is completed, the first main relay 101 and the second main relay 103 are immediately controlled to be attracted. At this time, the first AC pre-charging resistor R1 is in a short-circuit state, and the power consumption of the first AC pre-charging resistor R1 is 0. Accordingly, the first AC pre-charging resistor R1 will not heat up.

[0028] Based on this, the pre-charging of the DC bus capacitor and the pre-charging of the AC capacitor are handled separately. The DC pre-charging is completed through a dedicated DC pre-charging circuit when the main relay is disconnected, while the AC pre-charging is a process of pre-charging the capacitor in the electromagnetic interference module 11 after the DC bus capacitor pre-charging is completed and before the main relay is closed. The present application decouples the AC capacitor pre-charging and the DC bus capacitor pre-charging from the circuit, separates the pre-charging path, and connects the corresponding pre-charging circuit only when needed by controlling different relays, and keeps the corresponding circuit disconnected when pre-charging is not needed, thereby avoiding unnecessary current flowing through the pre-charging resistor, and the pre-charging resistor will not generate power consumption and heat, thereby effectively solving the problem of damage caused by the pre-charging resistor being in the AC and DC circuits for a long time in the standby state.

[0029] Figure 2 A schematic diagram of a first AC pre-charging module provided in an embodiment of the present application is shown. Figure 2 As shown, the first AC pre-charging relays RlyPre1 of the first AC pre-charging module 102 are connected in series, and one end of the first first AC pre-charging relay RlyPre1 is connected to one end of the first main relay 101, the other end of the last first AC pre-charging relay RlyPre1 is connected to one end of the first AC pre-charging resistor R1, and the other end of the first AC pre-charging resistor R1 is connected to the other end of the first main relay 101.

[0030] Figure 3 A schematic diagram of a second AC pre-charging module provided in an embodiment of the present application is shown. Figure 3As shown, the second AC pre-charging module 104 includes: a second AC pre-charging resistor R2 and at least one second AC pre-charging relay RlyPre2. The second AC pre-charging relays RlyPre2 in the second AC pre-charging module 104 are connected in series, and one end of the first second AC pre-charging relay RlyPre2 is connected to one end of the second main relay 103, the other end of the last second AC pre-charging relay RlyPre2 is connected to one end of the second AC pre-charging resistor R2, and the other end of the second AC pre-charging resistor R2 is connected to the other end of the second main relay 103.

[0031] Figure 4 FIG. 2 shows a schematic diagram of another pre-charging circuit provided in an embodiment of the present application. Figure 4 As shown, the first DC pre-charging module 105 includes: a first DC pre-charging relay RlyPre3, a second DC pre-charging relay RlyPre4, a first DC pre-charging resistor R3, a second DC pre-charging resistor R4, a first DC pre-charging diode D1 and a second DC pre-charging diode D2.

[0032] Optionally, refer to Figure 4 As shown, the conduction directions of the first DC pre-charge diode D1 and the second DC pre-charge diode D2 are the same. One end of the first DC pre-charge relay RlyPre3 is connected to one end of the second AC pre-charge relay RlyPre2, the other end of the first DC pre-charge relay RlyPre3 is connected to one end of the first DC pre-charge resistor R3, and the other end of the first DC pre-charge resistor R3 is connected to the other end of the second main relay 103. One end of the first DC pre-charge diode D1 is connected to the other end of the second main relay 103, the other end of the first DC pre-charge diode D1 is connected to one end of the second DC pre-charge diode D2, one end of the second DC pre-charge relay RlyPre4 is connected to one end of the first AC pre-charge relay RlyPre1, the other end of the second DC pre-charge relay RlyPre4 is connected to one end of the second DC pre-charge resistor R4, and the other end of the second DC pre-charge resistor R4 is connected to the other end of the second DC pre-charge diode D2.

[0033] It should be noted that the first DC pre-charging resistor R3 and the second DC pre-charging resistor R4 may also be combined into one DC pre-charging resistor and connected in series after the connection point of the first DC pre-charging diode D1 or the second DC pre-charging diode D2.

[0034] Optionally, refer to Figure 5As shown, the conduction directions of the first DC pre-filling diode D1 and the second DC pre-filling diode D2 can also be opposite. On this basis, one end of the first DC pre-filling relay RlyPre3 is connected to one end of the second AC pre-filling relay RlyPre2, the other end of the first DC pre-filling relay RlyPre3 is connected to one end of the first DC pre-filling resistor R3, and the other end of the first DC pre-filling resistor R3 is connected to the other end of the second main relay 103. One end of the first DC pre-filling diode D1 is connected to the other end of the second main relay 103, and the other end of the first DC pre-filling diode D1 is connected to one end of the bus capacitor module 13. One end of the second DC pre-filling relay RlyPre4 is connected to one end of the first AC pre-filling relay RlyPre1, the other end of the second DC pre-filling relay RlyPre4 is connected to one end of the second DC pre-filling resistor R4, the other end of the second DC pre-filling resistor R4 is connected to one end of the second DC pre-filling diode D2, and the other end of the second DC pre-filling diode D2 is connected to the other end of the bus capacitor module.

[0035] It should be noted that Figure 4 The pre-charging circuit shown is a three-phase single-stage dual half-bridge relay DC pre-charging circuit. Figure 5 The pre-charging circuit shown is a three-phase positive and negative dual half-bridge dual-relay DC pre-charging circuit. Figure 4 and Figure 5 The main difference between the pre-charging circuit shown is that the first DC pre-charging diode D1 and the second DC pre-charging diode D2 are directed differently, and thus there are some differences in the connection lines. On this basis, Figure 5 The DC charging circuit corresponding to the pre-charging circuit shown, that is, the pre-charging circuit for charging the bus capacitor module 13, is composed of three circuits, that is, the bus capacitor module 13 can be pre-charged when any phase voltage is missing. The pre-charging circuit can specifically be composed of the upper and lower bridge diodes of the third phase branch (W phase), the first DC pre-charging relay RlyPre3, the second DC pre-charging relay RlyPre4, the first DC pre-charging resistor R3, the second DC pre-charging resistor R4, the first DC pre-charging diode D1 and the second DC pre-charging diode D2. In the standby state, the first AC pre-charging relay RlyPre1, the second AC pre-charging relay RlyPre2, the first main relay 101 and the second main relay 103 are in the disconnected state, and the first DC pre-charging relay RlyPre3 and the second DC pre-charging relay RlyPre4 are controlled by an external wake-up signal to close to form a charging circuit. When Cbus is charged to the maximum line voltage, charging stops automatically. At this time, the power consumption of the first AC pre-charging resistor R1 is 0, and accordingly, the heat generation of the first AC pre-charging resistor R1 is also very small, or even does not generate heat. When the electromagnetic interference module 11 is precharged, Figure 4 and Figure 5The charging circuit corresponding to the pre-charging circuit shown is the same and will not be described again here.

[0036] Figure 6 FIG. 2 shows a schematic diagram of another pre-charging circuit provided in an embodiment of the present application. Figure 6 As shown, the second DC pre-charging module includes: a third DC pre-charging relay RlyPre5, a fourth DC pre-charging relay RlyPre6, a third DC pre-charging resistor R5, a third DC pre-charging diode D3 and a fourth DC pre-charging diode D4.

[0037] Optionally, one end of the third DC pre-charging relay RlyPre5 is connected to one end of the second main relay 103 through the third AC pre-charging resistor R6, the other end of the third DC pre-charging relay RlyPre5 is connected to one end of the fourth DC pre-charging relay RlyPre6, the other end of the fourth DC pre-charging relay RlyPre6 is respectively connected to the other end of the second main relay 103 and one end of the third DC pre-charging resistor R5, the other end of the third DC pre-charging resistor R5 is connected to one end of the third DC pre-charging diode D3, the other end of the third DC pre-charging diode D3 is connected to one end of the fourth DC pre-charging diode D4, and the other end of the fourth DC pre-charging diode D4 is connected to one end of the bus capacitor module 13.

[0038] Optionally, refer to Figure 7 As shown, one end of the third DC pre-charging relay RlyPre5 is connected to one end of the second main relay 103, the other end of the third DC pre-charging relay RlyPre5 is connected to one end of the fourth DC pre-charging relay RlyPre6, the other end of the fourth DC pre-charging relay RlyPre6 is connected to the other end of the second main relay 103 through the third AC pre-charging resistor R6, and the other end of the fourth DC pre-charging relay RlyPre6 is connected to one end of the third DC pre-charging resistor R5, the other end of the third DC pre-charging resistor R5 is connected to one end of the third DC pre-charging diode D3, the other end of the third DC pre-charging diode D3 is connected to one end of the fourth DC pre-charging diode D4, and the other end of the fourth DC pre-charging diode D4 is connected to one end of the bus capacitor module 13.

[0039] It should be noted that Figure 7 The precharge circuit shown is Figure 6 The difference between the pre-charging circuit shown is the position of the third AC pre-charging resistor R6 and the number of the first AC pre-charging relays RlyPre1. Figure 8 The precharge circuit shown is Figure 6 The difference between the pre-charging circuit shown is the position of the third AC pre-charging resistor R6. Fig. 9 The precharge circuit shown is Figure 6The difference between the pre-charging circuit shown is the number of the first AC pre-charging relays RlyPre1. Figure 6 , Figure 7 , Figure 8 as well as Fig. 9 The pre-charging circuits shown are all three-phase single half-bridge AC / DC hybrid decoupled pre-charging circuits, the only difference between them is the number of the first AC pre-charging relays RlyPre1 and the position of the third AC pre-charging resistor R6. This difference is caused by the selection of components based on the actual application scenario, and will not cause any changes to the pre-charging circuit and control method of the pre-charging circuit.

[0040] On this basis, Figure 6 , Figure 7 , Figure 8 as well as Fig. 9 The DC pre-charging principle corresponding to the pre-charging circuit shown is as follows: the charging circuit of the busbar capacitor module 13 is composed of the third phase branch (W phase), the third DC pre-charging relay RlyPre5, the fourth DC pre-charging relay RlyPre6, the third DC pre-charging resistor R5, the third DC pre-charging diode D3 and the fourth DC pre-charging diode D4. In the standby state, the first AC pre-charging relay RlyPre1, the first main relay 101 and the second main relay 103 are all in the disconnected state, and the third DC pre-charging relay RlyPre5 is controlled to close by an external wake-up signal to form a pre-charging circuit. When Cbus is charged to the maximum line voltage, charging stops automatically. At this time, the power consumption of the first AC pre-charging resistor R1 is 0. Correspondingly, the heat generated by the first AC pre-charging resistor R1 is also very small, or even does not generate heat.

[0041] Optionally, Figure 6 , Figure 7 , Figure 8 as well as Fig. 9 The AC pre-charging principle corresponding to the pre-charging circuit shown is: after the busbar capacitor module 13 is pre-charged, the first main relay 101 and the second main relay 103 must be closed to output the main power. At this time, in order to prevent the first main relay 101 and the second main relay 103 from being too much pressure difference before being pulled in, causing electric shock and ablation, the X capacitor and the Y capacitor in the electromagnetic interference module 11 need to be pre-charged. The AC pre-charging circuit is composed of the first AC pre-charging relay RlyPre1, the third DC pre-charging relay RlyPre5, the fourth DC pre-charging relay RlyPre6, the first AC pre-charging resistor R1, the third AC pre-charging resistor R6, the X capacitor and the Y capacitor in the electromagnetic interference module 11, etc. The first AC pre-charging relay RlyPre1 and the fourth DC pre-charging relay RlyPre6 are controlled by the control chip to start the AC pre-charging. After the pre-charging is completed, the first main relay 101 and the second main relay 103 are immediately controlled to be pulled in. At this time, the first AC pre-charging resistor R1 is in a short-circuit state, the power consumption is 0, and no heat is generated.

[0042] As a possible implementation, refer to Fig. 9 As shown, the pre-charging circuit also includes: a protection module, which includes at least one varistor and at least one protection resistor. Among them, the varistor is used for lightning surge protection of the port. Lightning surge refers to transient overvoltage and overcurrent caused by lightning activity or other external factors. These transient overvoltage and overcurrent may cause serious damage to the charging equipment, and even cause equipment failure or damage. The varistor is set in the pre-charging circuit, relying on the nonlinear volt-ampere characteristics of the varistor. When the voltage exceeds its threshold, its resistance value will drop rapidly, thereby allowing a large current to pass, thereby playing a role in lightning surge protection.

[0043] Specifically, the varistor has voltage limiting and shunting functions. The voltage limiting function means that when the lightning surge voltage exceeds the threshold of the varistor, the varistor will quickly turn on and limit the voltage to a safe level, thereby protecting the back-end circuit from damage. The shunting function means that after the varistor is turned on, it will shunt most of the lightning surge current, thereby reducing the load on the back-end circuit and avoiding damage to the equipment due to overcurrent.

[0044] It should be noted that Figure 6 , Figure 7 , Figure 8 as well as Fig. 9 The connection form of the DC pre-charging circuit corresponding to the pre-charging circuit shown is a unidirectional form, that is, directly passing through the W phase / U phase or the W phase / V phase to complete the pre-charging function, and Figure 4 and Figure 5 The connection form of the DC pre-charging circuit corresponding to the pre-charging circuit shown is a bidirectional form, that is, the pre-charging function is completed through the W phase / U phase and the W phase / V phase.

[0045] Fig.10 A schematic diagram of a pre-filling control method provided in an embodiment of the present application is shown. Fig.10 As shown, based on the external control chip, a wake-up signal is sent to the charging module, and the wake-up signal is detected to be valid. If the charging module receives a valid wake-up signal, the DC pre-charging resistor is controlled to be connected to the pre-charging circuit, and the main relay and the AC pre-charging circuit are disconnected to start the DC bus pre-charging. At this time, the pre-charging system will change from the dormant state to the awakened state. After the DC bus pre-charging is completed, it is further detected whether the AC pre-charging condition is met, such as whether the line voltage of the bus capacitor module 13 reaches the maximum value. If the AC pre-charging condition is met, the AC pre-charging resistor is controlled to be connected to the pre-charging circuit, and the AC pre-charging is started, and the main relay is attracted after the AC pre-charging is completed.

[0046] Based on this, the pre-charging circuit provided in the present application decouples the AC capacitor pre-charging and the DC bus capacitor pre-charging from the circuit, that is, separates the AC and DC pre-charging paths from the circuit, thereby effectively solving the problem of the pre-charging resistor being damaged by heat caused by being in the AC and DC circuits for a long time in the standby state.

[0047] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A precharge circuit, characterized in that: The pre-charging circuit includes a pre-charging control circuit, an electromagnetic interference module, a three-phase power supply module and a bus capacitor module, the pre-charging control circuit includes a three-phase branch, the three-phase branch includes a first phase branch, a second phase branch and a third phase branch, and one end of each phase branch is respectively connected to one phase of the three-phase power supply module, and the other end of each phase branch is respectively connected to the bus capacitor module through the electromagnetic interference module; A first main relay and a first AC pre-charging module are provided on the first phase branch, and the first main relay is connected in parallel with the first AC pre-charging module, and the first AC pre-charging module includes a first AC pre-charging resistor and at least one first AC pre-charging relay; A second main relay is provided on the second phase branch, and the second main relay is connected in parallel with the second AC pre-charging module and the first DC pre-charging module, or the second main relay is connected in parallel with the second DC pre-charging module; When the bus capacitor module is precharged, the first main relay, the second main relay and the second AC precharge module are disconnected, and the first DC precharge module is turned on; or, the first main relay is disconnected, the second main relay is disconnected, and the second DC precharge module is turned on; When pre-charging the electromagnetic interference module, the first main relay is turned on, the second main relay and the first AC pre-charging module are turned on, and the first DC pre-charging module is disconnected; or, the first main relay is turned on, the second main relay and the second DC pre-charging module are disconnected.

2. precharge circuit according to claim 1, characterized in that, The first AC pre-charging relays in the first AC pre-charging module are connected in series, and one end of the first first AC pre-charging relay is connected to one end of the first main relay, the other end of the last first AC pre-charging relay is connected to one end of the first AC pre-charging resistor, and the other end of the first AC pre-charging resistor is connected to the other end of the first main relay.

3. precharge circuit according to claim 1, is characterized in that, The second AC pre-charging module includes: a second AC pre-charging resistor and at least one second AC pre-charging relay; Each of the second AC pre-charging relays is connected in series, and one end of the first second AC pre-charging relay is connected to one end of the second main relay, the other end of the last second AC pre-charging relay is connected to one end of the second AC pre-charging resistor, and the other end of the second AC pre-charging resistor is connected to the other end of the second main relay.

4. precharge circuit according to claim 1, is characterized in that, The first DC pre-charging module includes: a first DC pre-charging relay, a second DC pre-charging relay, a first DC pre-charging resistor, a second DC pre-charging resistor, a first DC pre-charging diode and a second DC pre-charging diode.

5. precharge circuit according to claim 4, characterized in that, The first DC pre-charging diode and the second DC pre-charging diode have the same conduction direction; One end of the first DC pre-charging relay is connected to one end of the second AC pre-charging relay, the other end of the first DC pre-charging relay is connected to one end of the first DC pre-charging resistor, and the other end of the first DC pre-charging resistor is connected to the other end of the second main relay; One end of the first DC pre-charging diode is connected to the other end of the second main relay, and the other end of the first DC pre-charging diode is connected to one end of the second DC pre-charging diode; One end of the second DC pre-charging relay is connected to one end of the first AC pre-charging relay, the other end of the second DC pre-charging relay is connected to one end of the second DC pre-charging resistor, and the other end of the second DC pre-charging resistor is connected to the other end of the second DC pre-charging diode.

6. precharge circuit according to claim 4, characterized in that, The conduction directions of the first DC pre-charging diode and the second DC pre-charging diode are opposite; One end of the first DC pre-charging relay is connected to one end of the second AC pre-charging relay, the other end of the first DC pre-charging relay is connected to one end of the first DC pre-charging resistor, and the other end of the first DC pre-charging resistor is connected to the other end of the second main relay; One end of the first DC pre-charging diode is connected to the other end of the second main relay, and the other end of the first DC pre-charging diode is connected to one end of the bus capacitor module; One end of the second DC pre-charging relay is connected to one end of the first AC pre-charging relay, the other end of the second DC pre-charging relay is connected to one end of the second DC pre-charging resistor, the other end of the second DC pre-charging resistor is connected to one end of the second DC pre-charging diode, and the other end of the second DC pre-charging diode is connected to the other end of the bus capacitor module.

7. precharge circuit according to claim 1, characterized in that, The second DC pre-charging module includes: a third DC pre-charging relay, a fourth DC pre-charging relay, a third DC pre-charging resistor, a third DC pre-charging diode and a fourth DC pre-charging diode; One end of the third DC pre-charging relay is connected to one end of the second main relay through the third AC pre-charging resistor, the other end of the third DC pre-charging relay is connected to one end of the fourth DC pre-charging relay, the other end of the fourth DC pre-charging relay is respectively connected to the other end of the second main relay and one end of the third DC pre-charging resistor, the other end of the third DC pre-charging resistor is connected to one end of the third DC pre-charging diode, the other end of the third DC pre-charging diode is connected to one end of the fourth DC pre-charging diode, and the other end of the fourth DC pre-charging diode is connected to one end of the bus capacitor module.

8. precharge circuit according to claim 7, it is characterized in that, One end of the third DC pre-charging relay is connected to one end of the second main relay, the other end of the third DC pre-charging relay is connected to one end of the fourth DC pre-charging relay, the other end of the fourth DC pre-charging relay is connected to the other end of the second main relay through the third AC pre-charging resistor, and the other end of the fourth DC pre-charging relay is connected to one end of the third DC pre-charging resistor, the other end of the third DC pre-charging resistor is connected to one end of the third DC pre-charging diode, the other end of the third DC pre-charging diode is connected to one end of the fourth DC pre-charging diode, and the other end of the fourth DC pre-charging diode is connected to one end of the bus capacitor module.

9. precharge circuit according to claim 1, characterized in that, The electromagnetic interference module is connected to the bus capacitor module through an inductor and a bridge diode.

10. The precharge circuit according to claim 1, characterized in that The pre-charging circuit further includes: a protection module; the protection module includes at least one varistor and at least one protection resistor; One end of the protection module is connected to the first DC pre-charging module or the second DC pre-charging module, and the other end of the protection module is connected to the electromagnetic interference module.

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