Precharge Circuit

Abstract

The present application provides a pre-charge circuit, which relates to the field of power electronics technology. The pre-charge circuit includes: a pre-charge control circuit, an electromagnetic interference module, a three-phase power supply module, and a bus capacitor module; when pre-charging the bus capacitor module, the first main relay, the second main relay, the first AC pre-charge module, 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; when pre-charging the electromagnetic interference module, the first AC pre-charge module is turned on, and the first DC pre-charge module is disconnected; or the second DC pre-charge module is disconnected. After the electromagnetic interference module is pre-charged, the first main relay and the second main relay are turned on. The present application effectively decouples the pre-charging of the AC capacitor and the pre-charging of the DC bus capacitor from the circuit by separating the pre-charge paths and controlling the on / off of different relays to connect the corresponding pre-charge circuits.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more particularly, to a pre-charge circuit. Background Art

[0002] In the design of the charging module of the existing charging pile, when the auxiliary power supply comes from the bus capacitor, the main relay usually does not close in the standby state. Therefore, in order to maintain the standby working state of the pre-charge 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 in the pre-charge loop are coupled together, that is, in the standby state, the pre-charge resistor not only undertakes the task of charging the bus capacitor, but also continuously bears the influence of the AC voltage, so that the pre-charge resistor is in the working state for a long time in the standby state, causing loss to the pre-charge resistor and generating unnecessary heat at the same time. The heating of the pre-charge resistor not only wastes energy, but also may cause the 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 this application is to provide a pre-charge circuit to solve the problem of the coupling of the AC-DC pre-charge loop in the prior art in view of the above deficiencies in the prior art.

[0004] To achieve the above object, the technical solution adopted in the embodiment of this application is as follows:

[0005] The embodiment of this application provides a pre-charge circuit, which includes a pre-charge control circuit, an electromagnetic interference module, a three-phase power supply module, and a bus capacitor module. The pre-charge control circuit includes a three-phase branch, and the three-phase branch includes a first-phase branch, a second-phase branch, and a third-phase branch. 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;

[0006] A first main relay and a first AC pre-charge module are arranged on the first-phase branch, and the first main relay and the first AC pre-charge module are connected in parallel. The first AC pre-charge module includes a first AC pre-charge resistor and at least one first AC pre-charge relay;

[0007] A second main relay is arranged on the second-phase branch, and the second main relay is connected in parallel with a second AC pre-charge module and a first DC pre-charge module, or the second main relay is connected in parallel with a second DC pre-charge module;

[0008] When pre-charging the bus capacitor module, the first main relay, the second main relay, the first AC pre-charging module, and the second AC pre-charging module are disconnected, and the first DC pre-charging module is turned on; or, the first main relay is disconnected, the second main relay is disconnected, and the second DC pre-charging module is turned on;

[0009] When pre-charging the electromagnetic interference module, the first AC pre-charging module and the second AC pre-charging module are turned on, and the first DC pre-charging module is disconnected; or, the second DC pre-charging module is disconnected, and after the electromagnetic interference module is pre-charged, the first main relay and the second main relay are turned on;

[0010] Among them, after the bus capacitor is pre-charged, the electromagnetic interference module is pre-charged, and when the bus capacitor module is charged to the line voltage reaching a preset value, or when the electromagnetic interference module is pre-charged, the power consumption of the first AC pre-charging resistor is zero;

[0011] 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;

[0012] One end of the third DC pre-charging relay is connected to one end of the second main relay through a 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.

[0013] As a possible implementation, 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, and 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.

[0014] 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;

[0015] Each of the second AC pre-charge relays is connected in series, and one end of the first second AC pre-charge relay is connected to one end of the second main relay, and the other end of the last second AC pre-charge relay is connected to one end of the second AC pre-charge resistor, and the other end of the second AC pre-charge resistor is connected to the other end of the second main relay.

[0016] As a possible implementation, the first DC pre-charge module includes: a first DC pre-charge relay, a second DC pre-charge relay, a first DC pre-charge resistor, a second DC pre-charge resistor, a first DC pre-charge diode, and a second DC pre-charge diode.

[0017] As a possible implementation, the conduction directions of the first DC pre-charge diode and the second DC pre-charge diode are the same;

[0018] One end of the first DC pre-charge relay is connected to one end of the second AC pre-charge relay, the other end of the first DC pre-charge relay is connected to one end of the first DC pre-charge resistor, and the other end of the first DC pre-charge resistor is connected to the other end of the second main relay;

[0019] One end of the first DC pre-charge diode is connected to the other end of the second main relay, and the other end of the first DC pre-charge diode is connected to one end of the second DC pre-charge diode;

[0020] One end of the second DC pre-charge relay is connected to one end of the first AC pre-charge relay, the other end of the second DC pre-charge relay is connected to one end of the second DC pre-charge resistor, and the other end of the second DC pre-charge resistor is connected to the other end of the second DC pre-charge diode.

[0021] As a possible implementation, the conduction directions of the first DC pre-charge diode and the second DC pre-charge diode are opposite;

[0022] One end of the first DC pre-charge relay is connected to one end of the second AC pre-charge relay, the other end of the first DC pre-charge relay is connected to one end of the first DC pre-charge resistor, and the other end of the first DC pre-charge resistor is connected to the other end of the second main relay;

[0023] One end of the first DC pre-charge diode is connected to the other end of the second main relay, and the other end of the first DC pre-charge diode is connected to one end of the bus capacitor module;

[0024] One end of the second DC pre-charge relay is connected to one end of the first AC pre-charge relay. The other end of the second DC pre-charge relay is connected to one end of the second DC pre-charge resistor. The other end of the second DC pre-charge resistor is connected to one end of the second DC pre-charge diode. The other end of the second DC pre-charge diode is connected to the other end of the bus capacitor module.

[0025] As a possible implementation, one end of the third DC pre-charge relay is connected to one end of the second main relay. The other end of the third DC pre-charge relay is connected to one end of the fourth DC pre-charge relay. The other end of the fourth DC pre-charge relay is connected to the other end of the second main relay through a third AC pre-charge resistor. And the other end of the fourth DC pre-charge relay is connected to one end of the third DC pre-charge resistor. The other end of the third DC pre-charge resistor is connected to one end of the third DC pre-charge diode. The other end of the third DC pre-charge diode is connected to one end of the fourth DC pre-charge diode. The other end of the fourth DC pre-charge diode is connected to one end of the bus capacitor module.

[0026] As a possible implementation, the electromagnetic interference module is connected to the bus capacitor module through an inductor and a bridge diode.

[0027] As a possible implementation, the pre-charge circuit further includes: a protection module; the protection module includes at least one varistor and at least one protection resistor;

[0028] One end of the protection module is connected to the first DC pre-charge module or the second DC pre-charge module. The other end of the protection module is connected to the electromagnetic interference module.

[0029] According to the precharge circuit of the embodiment of the present application, the precharge circuit includes a precharge control circuit, an electromagnetic interference module, a three-phase power supply module, and a bus capacitor module. The precharge control circuit includes a three-phase branch, and the three-phase branch includes a first-phase branch, a second-phase branch, and a third-phase branch. 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 precharge module are provided on the first-phase branch, and the first main relay and the first AC precharge module are connected in parallel. The first AC precharge module includes a first AC precharge resistor and at least one first AC precharge relay. A second main relay is provided on the second-phase branch, and the second main relay is connected in parallel with a second AC precharge module and a first DC precharge module, or the second main relay is connected in parallel with a second DC precharge module. On this basis, when precharging the bus capacitor module, the first main relay, the second main relay, the first AC precharge module, 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 precharging the electromagnetic interference module, the first AC precharge module and the second AC precharge module are turned on, and the first DC precharge module is disconnected; or the second DC precharge module is disconnected. After the electromagnetic interference module is precharged, the first main relay and the second main relay are turned on. It can be seen that the precharge circuit provided by the present application decouples the AC capacitor precharge and the DC bus capacitor precharge circuitually, and connects the corresponding precharge circuits by separating the precharge paths and controlling the on / off of different relays. Specifically, by controlling different relays, the corresponding precharge circuits are only turned on when needed, and the corresponding circuits are kept disconnected when precharging is not required, so as to avoid unnecessary current flowing through the precharge resistors, and the precharge resistors will not generate power consumption and heat, thus effectively solving the problem that the precharge resistors are damaged due to heating when they are in the AC and DC circuits for a long time in the standby state. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 Shows a schematic diagram of a precharge circuit provided by an embodiment of the present application;

[0032] Figure 2 Shows a schematic diagram of a first AC precharge module provided by an embodiment of the present application;

[0033] Figure 3 The figure shows a schematic diagram of a second AC pre-charge module provided by an embodiment of the present application;

[0034] Figure 4 The figure shows a schematic diagram of another pre-charge circuit provided by an embodiment of the present application;

[0035] Figure 5 The figure shows a schematic diagram of yet another pre-charge circuit provided by an embodiment of the present application;

[0036] Figure 6 The figure shows a schematic diagram of yet another pre-charge circuit provided by an embodiment of the present application;

[0037] Figure 7 The figure shows a schematic diagram of yet another pre-charge circuit provided by an embodiment of the present application;

[0038] Figure 8 The figure shows a schematic diagram of yet another pre-charge circuit provided by an embodiment of the present application;

[0039] Figure 9 The figure shows a schematic diagram of yet another pre-charge circuit provided by an embodiment of the present application;

[0040] Figure 10 The figure shows a schematic flow chart of a pre-charge control method provided by an embodiment of the present application. Detailed implementation manners

[0041] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only for the purposes of illustration and description, and are not used to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn to actual scale. The flow charts used in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations in the flow charts may not be implemented in sequence, and steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flow charts or remove one or more operations from the flow charts under the guidance of the content of the present application.

[0042] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. 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 claimed, but only represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts fall within the protection scope of the present application.

[0043] It should be noted that the term "including" will be used in the embodiments of the present application to indicate the presence of the features stated thereafter, but does not exclude the addition of other features.

[0044] In the prior art, the AC and DC pre-charge circuits are coupled together, resulting in the pre-charge resistor heating up in the standby state. To address this issue, the present application provides a pre-charge circuit for the pre-charge circuit of the main relay at the port. The pre-charge of the AC capacitor and the pre-charge of the DC bus capacitor are decoupled circuit-wise. Specifically, by controlling the on / off of different relays, the corresponding pre-charge circuits are connected, that is, by separating the pre-charge paths, the loss caused by the AC current to the pre-charge resistor during standby is effectively reduced.

[0045] Figure 1 The schematic diagram of a pre-charge circuit provided by an embodiment of the present application is shown. Referring to Figure 1 As shown, the pre-charge circuit includes a pre-charge 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-charge 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. 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.

[0046] Optionally, referring 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. Among them, a first main relay 101 and a first AC pre-charge module 102 are provided on the first-phase branch, and the first main relay 101 and the first AC pre-charge module 102 are connected in parallel. The first AC pre-charge module 102 includes a first AC pre-charge resistor R1 and at least one first AC pre-charge relay RlyPre1.

[0047] 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-charge module 104 and the first DC pre-charge module 105, or the second main relay 103 is connected in parallel with the second DC pre-charge module. It should be noted here that Figure 1 The connection schematic diagram shows the second main relay 103 connected in parallel with the second AC pre-charge module 104 and the first DC pre-charge module 105, but the second main relay 103 can also be directly connected in parallel with the second DC pre-charge module, that is, replacing the second AC pre-charge module 104 and the first DC pre-charge module 105 with the second DC pre-charge module.

[0048] Optionally, when pre-charging the bus capacitor module 13, the first main relay 101, the second main relay 103, the first AC pre-charging module 102, 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.

[0049] Exemplarily, the electromagnetic interference module 11 is connected to the bus capacitor module 13 through an inductor and a bridge diode. The bus capacitor module 13 includes a first capacitor and a second capacitor. When pre-charging the bus capacitor module 13, the charging circuit is composed of the upper-bridge diode of the third-phase branch (W-phase branch) and the first DC pre-charging module 105, or is composed of the upper-bridge diode of the third-phase branch (W-phase branch) and the second DC pre-charging module. In the standby state, the first main relay 101, the second main relay 103, the first AC pre-charging relay RlyPre1 in the first AC pre-charging module 102, and the second AC pre-charging relay RlyPre2 in the second AC pre-charging module 104 are all in the off state. The first DC pre-charging relay in the first DC pre-charging module 105, or the second DC pre-charging relay in the second DC pre-charging module is controlled by an external wake-up signal to be closed to form a charging circuit for charging the bus capacitor module 13. Further, when the line voltage of the bus capacitor module 13 reaches a preset value, for example, the maximum line voltage value, the charging of the bus capacitor module 13 is automatically stopped. At this time, the power consumption of the first AC pre-charging resistor R1 is 0. Correspondingly, the heat generation of the first AC pre-charging resistor R1 is also very small, or even no heat is generated.

[0050] Optionally, when pre-charging the electromagnetic interference module 11, the first AC pre-charging module 102 and the second AC pre-charging module 104 are turned on, and the first DC pre-charging module 105 is disconnected; or, the second DC pre-charging module is disconnected, and after the pre-charging of the electromagnetic interference module 11 is completed, the first main relay 101 and the second main relay 103 are turned on.

[0051] Exemplarily, after the bus capacitor module 13 is pre-charged, the first main relay and the second main relay need to be closed to perform the main power output. At this time, in order to prevent excessive voltage difference across the first main relay and the second main relay before closing, which may cause contact ablation, the electromagnetic interference module 11 needs to be pre-charged, that is, the capacitor in the electromagnetic interference module 11 is pre-charged. At this time, the charging circuit consists of the first AC pre-charge relay RlyPre1, the first AC pre-charge resistor R1, the second AC pre-charge relay and the second AC pre-charge resistor in the second AC pre-charge module 104, and the capacitor in the electromagnetic interference module 11. By controlling the first AC pre-charge relay RlyPre1 and the second AC pre-charge relay to start AC pre-charging, and immediately controlling the first main relay 101 and the second main relay 103 to close after the pre-charging is completed. At this time, the first AC pre-charge resistor R1 is in a short-circuit state, and the power consumption of the first AC pre-charge resistor R1 is 0. Correspondingly, the first AC pre-charge resistor R1 does not heat up.

[0052] Based on this, the pre-charging of the DC bus capacitor and the AC capacitor is processed separately. The DC pre-charging is completed through a dedicated DC pre-charge circuit when the main relay is open, while the AC pre-charging is a process of specifically pre-charging the capacitor in the electromagnetic interference module 11 after the DC bus capacitor is pre-charged and before closing the main relay. In this application, the AC capacitor pre-charging and the DC bus capacitor pre-charging are decoupled from the circuit, and the pre-charge paths are separated. By controlling different relays, the corresponding pre-charge circuit is only connected when needed, and the corresponding circuit is kept open 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, thus effectively solving the problem that the pre-charge resistor is damaged due to long-term heating in both the AC and DC circuits during the standby state.

[0053] Figure 2 FIG. shows a schematic diagram of a first AC pre-charge module provided by an embodiment of the present application. Referring to Figure 2 As shown, the first AC pre-charge relays RlyPre1 of the first AC pre-charge module 102 are connected in series. Moreover, one end of the first first AC pre-charge relay RlyPre1 is connected to one end of the first main relay 101, and the other end of the last first AC pre-charge relay RlyPre1 is connected to one end of the first AC pre-charge resistor R1, and the other end of the first AC pre-charge resistor R1 is connected to the other end of the first main relay 101.

[0054] Figure 3 FIG. shows a schematic diagram of a second AC pre-charge module provided by an embodiment of the present application. Referring to Figure 3As shown, the second AC pre-charge module 104 includes: a second AC pre-charge resistor R2 and at least one second AC pre-charge relay RlyPre2. The second AC pre-charge relays RlyPre2 in the second AC pre-charge module 104 are connected in series. One end of the first second AC pre-charge relay RlyPre2 is connected to one end of the second main relay 103, and the other end of the last second AC pre-charge relay RlyPre2 is connected to one end of the second AC pre-charge resistor R2. The other end of the second AC pre-charge resistor R2 is connected to the other end of the second main relay 103.

[0055] Figure 4 FIG. shows a schematic diagram of another pre-charge circuit provided by an embodiment of the present application. Refer to Figure 4 As shown, the first DC pre-charge module 105 includes: a first DC pre-charge relay RlyPre3, a second DC pre-charge relay RlyPre4, a first DC pre-charge resistor R3, a second DC pre-charge resistor R4, a first DC pre-charge diode D1, and a second DC pre-charge diode D2.

[0056] 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. 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. 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.

[0057] It should be noted that the first DC pre-charge resistor R3 and the second DC pre-charge resistor R4 can also be combined into a single DC pre-charge resistor and connected in series after the connection point of the first DC pre-charge diode D1 or the second DC pre-charge diode D2.

[0058] Optionally, refer to Figure 5As shown, the conduction directions of the first DC pre-charge diode D1 and the second DC pre-charge diode D2 can also be opposite. On this basis, 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, and the other end of the first DC pre-charge diode D1 is connected to one end of the bus capacitor module 13. 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, the other end of the second DC pre-charge resistor R4 is connected to one end of the second DC pre-charge diode D2, and the other end of the second DC pre-charge diode D2 is connected to the other end of the bus capacitor module.

[0059] It should be noted that Figure 4 the pre-charge circuit shown is a three-phase single-stage double-half-bridge relay DC pre-charge circuit, Figure 5 the pre-charge circuit shown is a three-phase positive and negative double-half-bridge double-relay DC pre-charge circuit, Figure 4 and Figure 5 the main difference from the pre-charge circuit shown lies in the different orientations of the first DC pre-charge diode D1 and the second DC pre-charge diode D2, and thus there are some differences in the connection lines. On this basis, Figure 5 the DC charging loop corresponding to the pre-charge circuit shown, that is, the pre-charge loop for charging the bus capacitor module 13, is composed of three loops, that is, the bus capacitor module 13 can be pre-charged when any one phase voltage is missing. The specific pre-charge loop can be composed of the upper and lower bridge diodes of the third-phase branch (W phase), the first DC pre-charge relay RlyPre3, the second DC pre-charge relay RlyPre4, the first DC pre-charge resistor R3, the second DC pre-charge resistor R4, the first DC pre-charge diode D1, and the second DC pre-charge diode D2. In the standby state, the first AC pre-charge relay RlyPre1, the second AC pre-charge relay RlyPre2, the first main relay 101, and the second main relay 103 are in the off state. The first DC pre-charge relay RlyPre3 and the second DC pre-charge relay RlyPre4 are controlled to close through an external wake-up signal to form a charging loop. When Cbus is charged to the maximum line voltage, the charging automatically stops. At this time, the power consumption of the first AC pre-charge resistor R1 is 0, and correspondingly, the heat generation of the first AC pre-charge resistor R1 is very small, or even does not generate heat. When pre-charging the electromagnetic interference module 11, Figure 4 and Figure 5The charging circuits corresponding to the pre-charging circuits shown are the same, and will not be elaborated here.

[0060] Figure 6 The figure shows a schematic diagram of another pre-charging circuit provided by an embodiment of the present application. Refer to 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.

[0061] Optionally, one end of the third DC pre-charging relay RlyPre5 is connected to one end of the second main relay 103 through a 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. The other end of the fourth DC pre-charging diode D4 is connected to one end of the bus capacitor module 13.

[0062] 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 a 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. The other end of the fourth DC pre-charging diode D4 is connected to one end of the bus capacitor module 13.

[0063] It should be noted that Figure 7 The difference between the pre-charging circuit shown and Figure 6 the pre-charging circuit shown lies in the different positions of the third AC pre-charging resistor R6 and the number of the first AC pre-charging relays RlyPre1. Figure 8 The difference between the pre-charging circuit shown and Figure 6 the pre-charging circuit shown lies in the position of the third AC pre-charging resistor R6. Figure 9 The difference between the pre-charging circuit shown and Figure 6The difference between the pre-charge circuits shown lies in the number of the first AC pre-charge relays RlyPre1. That is to say, Figure 6 , Figure 7 , Figure 8 and Figure 9 The pre-charge circuits shown are all three-phase single half-bridge AC-DC hybrid decoupled pre-charge circuits. The difference lies only in the number of the first AC pre-charge relays RlyPre1 and the position of the third AC pre-charge resistor R6. This difference is caused by the selection of components according to the actual application scenario and does not change the pre-charge loop and control method of the pre-charge circuit.

[0064] On this basis, Figure 6 , Figure 7 , Figure 8 and Figure 9 The corresponding DC pre-charge principle of the pre-charge circuits shown is as follows: The charging loop of the bus capacitor module 13 is composed of the third-phase branch (W phase), the third DC pre-charge relay RlyPre5, the fourth DC pre-charge relay RlyPre6, the third DC pre-charge resistor R5, the third DC pre-charge diode D3, and the fourth DC pre-charge diode D4. In the standby state, the first AC pre-charge relay RlyPre1, the first main relay 101, and the second main relay 103 are all in the open state. The third DC pre-charge relay RlyPre5 is controlled to close through an external wake-up signal to form a pre-charge loop. When Cbus is charged to the maximum line voltage, the charging stops automatically. At this time, the power consumption of the first AC pre-charge resistor R1 is 0, and correspondingly, the heat generation of the first AC pre-charge resistor R1 is very small, or even does not generate heat.

[0065] Optionally, Figure 6 , Figure 7 , Figure 8 and Figure 9 The corresponding AC pre-charge principle of the pre-charge circuits shown is as follows: After the bus capacitor module 13 is pre-charged, the first main relay 101 and the second main relay 103 need to be closed to perform the main power output. At this time, in order to prevent the voltage difference across the first main relay 101 and the second main relay 103 from being too large before closing and causing contact ablation, the X capacitor and Y capacitor in the electromagnetic interference module 11 need to be pre-charged. The AC pre-charge loop is composed of the first AC pre-charge relay RlyPre1, the third DC pre-charge relay RlyPre5, the fourth DC pre-charge relay RlyPre6, the first AC pre-charge resistor R1, the third AC pre-charge resistor R6, the X capacitor and Y capacitor in the electromagnetic interference module 11, etc. The first AC pre-charge relay RlyPre1 and the fourth DC pre-charge relay RlyPre6 are controlled by the control chip to start the AC pre-charge. After the pre-charge is completed, the first main relay 101 and the second main relay 103 are immediately controlled to close. At this time, the first AC pre-charge resistor R1 is in a short-circuit state, with a power consumption of 0 and no heat generation.

[0066] As a possible implementation, referring to Figure 9 As shown, the pre-charge circuit further 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 activities or other external factors. These transient overvoltages and overcurrents may cause serious damage to the charging device, and even lead to device failure or damage. By setting a varistor in the pre-charge circuit, relying on the non-linear volt-ampere characteristic of the varistor, when the voltage exceeds its threshold, its resistance value will rapidly decrease, thereby allowing a large current to pass through, so as to play the role of lightning surge protection.

[0067] Specifically, the varistor has a voltage limiting effect and a current shunting effect. The voltage limiting effect means that when the lightning surge voltage exceeds the threshold of the varistor, the varistor will conduct rapidly, limiting the voltage within a safe level, thereby protecting the backend circuit from damage. The current shunting effect means that after the varistor conducts, it will shunt most of the lightning surge current, thereby reducing the load on the backend circuit and avoiding damage to the device due to overcurrent.

[0068] It should be noted that Figure 6 , Figure 7 , Figure 8 and Figure 9 The connection form of the DC pre-charge loop corresponding to the pre-charge circuit shown is a unidirectional form, that is, directly connecting to the W phase / U phase or the W phase / V phase to complete the pre-charge function. And Figure 4 and Figure 5 The connection form of the DC pre-charge loop corresponding to the pre-charge circuit shown is a bidirectional form, that is, completing the pre-charge function through the W phase / U phase and the W phase / V phase.

[0069] Figure 10 The flowchart of a pre-charge control method provided by an embodiment of the present application is shown. Referring to Figure 10 As shown, based on the external control chip sending a wake-up signal to the charging module and detecting whether the wake-up signal is valid. If the charging module receives a valid wake-up signal, it controls the DC pre-charge resistor to be connected to the pre-charge circuit, and disconnects the main relay and the AC pre-charge circuit to start the DC bus pre-charge. At this time, the pre-charge system will change from the sleep state to the wake-up state. After the DC bus pre-charge is completed, it further detects whether the AC pre-charge condition is met. For example, whether the line voltage of the bus capacitor module 13 reaches the maximum value. If the AC pre-charge condition is met, it controls the AC pre-charge resistor to be connected to the pre-charge circuit, starts the AC pre-charge, and closes the main relay after the AC pre-charge is completed.

[0070] Based on this, the pre-charge circuit provided by this application decouples the pre-charge of the AC capacitor and the pre-charge of the DC bus capacitor from the circuit, that is, separates the AC and DC pre-charge paths from the circuit, thus effectively solving the problem that the pre-charge resistor is damaged due to heating when it is in the AC and DC circuits simultaneously for a long time in the standby state.

[0071] The above are only specific embodiments of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this 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, the first AC precharge module 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 the electromagnetic interference module is pre-charged, the first AC pre-charge module and the second AC pre-charge module are turned on, and the first DC pre-charge module is turned off; or, the second DC pre-charge module is turned off, and after the electromagnetic interference module is pre-charged, the first main relay and the second main relay are turned on; Wherein, after the bus capacitor is pre-charged, the electromagnetic interference module is pre-charged, and when the bus capacitor module is charged until the line voltage reaches a preset value, or the electromagnetic interference module is pre-charged, the power consumption of the first AC pre-charging resistor is zero; 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.

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, 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, 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.

8. 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.

9. 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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