Direct current charging circuit and direct current charging method

Abstract

The invention discloses a direct current charging circuit and a direct current charging method, and relates to the technical field of electric vehicle charging. The circuit includes: a bidirectional DC converter including a low voltage port and a high voltage port; two ends of the low-voltage port are respectively connected with positive and negative electrodes of a low-voltage auxiliary battery of the vehicle; two ends of the high-voltage port are respectively connected with high-voltage direct-current buses connected to positive and negative electrodes of a vehicle power battery; positive and negative electrodes of a first charging interface of the vehicle charging socket are respectively connected with the high-voltage direct-current bus at two ends of the high-voltage port, and the positive electrode is connected with the high-voltage direct-current bus through a relay; and the bidirectional direct current converter is used for converting high-voltage electricity transmitted by the power supply equipment through the charging socket in a constant-voltage mode or a constant-current mode into low-voltage electricity and then charging the low-voltage auxiliary battery under the condition that the low-voltage auxiliary battery and the power battery are both in a feed state. According to the invention, deep discharge of the power battery caused by the fact that the fed power battery supplies power to the low-voltage auxiliary battery can be avoided, so that a battery cell of the power battery is prevented from being damaged.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicle charging, and in particular to a direct current charging circuit and a direct current charging method. Background Art

[0002] When the low-voltage auxiliary battery (also known as 12v battery or 12v small battery) of an electric vehicle is in a feeding state or is low in power, the relevant technology usually recharges the low-voltage auxiliary battery through an external portable power supply device or the power battery of the electric vehicle. The external portable power supply device needs to be carried by the user at all times, and the user experience is low. Therefore, recharging the low-voltage auxiliary battery through the power battery of the electric vehicle is the mainstream recharging method. When the power battery and the low-voltage auxiliary battery are in the feeding state at the same time, recharging the low-voltage auxiliary battery through the power battery will cause the power battery to be deeply discharged, damaging the battery cell of the power battery. Summary of the invention

[0003] In response to the above technical problems, the embodiments of the present application provide a DC charging circuit and a DC charging method, which can avoid deep discharge of the power battery caused by the power battery that has already been powered replenishing power to the low-voltage auxiliary battery, thereby avoiding damage to the power battery cells.

[0004] The technical solution of this application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a DC charging circuit, including: a bidirectional DC converter, wherein the bidirectional DC converter includes a low voltage port and a high voltage port;

[0006] The two ends of the low-voltage port are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle;

[0007] The two ends of the high-voltage port are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at the two ends of the high-voltage port, and the positive electrode of the first charging interface is connected to the high-voltage DC bus through a relay;

[0008] The bidirectional DC converter is used to: when the low-voltage auxiliary battery and the power battery are both in a feeding state, convert the high-voltage electricity transmitted by the power supply device through the first charging interface of the charging socket in a constant voltage mode or a constant current mode into low-voltage electricity to charge the low-voltage auxiliary battery. The power supply device is a device used to charge the vehicle.

[0009] In some embodiments, a first end of the two ends of the low-voltage port is connected to the positive electrode of the low-voltage auxiliary battery through a switch element, and a second end of the two ends of the low-voltage port is connected to the negative electrode of the low-voltage auxiliary battery;

[0010] The positive electrode of the second charging interface of the charging socket is connected to the first connection point through the first unidirectional conductive element, and the negative electrode of the second charging interface of the charging socket is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port and the switching element, and the second connection point is the connection point between the second end of the low-voltage port and the negative electrode of the low-voltage auxiliary battery;

[0011] The bidirectional DC converter is also used to convert the low voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high voltage electricity to pre-charge the bus capacitor on the high voltage DC bus.

[0012] In some embodiments, the DC charging circuit further includes a battery management controller;

[0013] The positive electrode of the second charging interface of the charging socket is connected to the battery management controller through the first unidirectional conductive element;

[0014] The positive electrode of the low-voltage auxiliary battery is connected to the battery management controller via a second unidirectional conductive element;

[0015] The battery management controller is also connected to a connection point between the negative electrode of the second charging interface of the charging socket and the negative electrode of the low-voltage auxiliary battery.

[0016] In some embodiments, the battery management controller is used to:

[0017] When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket, and both the low-voltage auxiliary battery and the power battery are in a feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

[0018] In some embodiments, the battery management controller is further configured to:

[0019] After determining that the bus capacitor on the high-voltage DC bus is pre-charged, sending a request message to the power supply device, the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode;

[0020] When it is determined that the power supply device transmits high voltage electricity through the first charging interface of the charging socket in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket into low voltage electricity for charging the low voltage auxiliary battery.

[0021] In some embodiments, the battery management controller is further configured to:

[0022] When it is determined that the power level of the low-voltage auxiliary battery reaches a preset power level, an instruction message is sent to the power supply device, where the instruction message is used to instruct the power supply device to restart the charging process to charge the power battery of the vehicle.

[0023] In some embodiments, the bidirectional DC converter further includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a first inductor, a second inductor, a first capacitor, a second capacitor and a transformer; the high voltage side of the transformer includes a first terminal and a second terminal, and the low voltage side of the transformer includes a third terminal, a fourth terminal and a fifth terminal;

[0024] The first MOS transistor and the second MOS transistor are connected in series to form a first series branch, the third MOS transistor and the fourth MOS transistor are connected in series to form a second series branch, the first series branch and the second series branch are connected in parallel, and both ends of the first series branch are both ends of the high-voltage port;

[0025] One end of the first inductor is connected to the connection line between the first MOS transistor and the second MOS transistor, and the other end of the first inductor is connected to the first terminal;

[0026] One end of the first capacitor is connected to the connection line between the third MOS transistor and the fourth MOS transistor, and the other end of the first capacitor is connected to the second terminal;

[0027] One end of the fifth MOS tube is connected to the third terminal, one end of the sixth MOS tube is connected to the fourth terminal, and the other end of the fifth MOS tube is connected to the other end of the sixth MOS tube;

[0028] One end of the second inductor is connected to the fifth terminal, the other end of the second inductor is connected to one end of the second capacitor, the other end of the second capacitor is connected to the other end of the sixth MOS tube, and both ends of the second capacitor are both ends of the low-voltage port.

[0029] In a second aspect, an embodiment of the present application provides a DC charging method, which is applied to a vehicle including a DC charging circuit, wherein the DC charging circuit includes a bidirectional DC converter, and the bidirectional DC converter includes a low-voltage port and a high-voltage port; the two ends of the low-voltage port are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle; the two ends of the high-voltage port are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at the two ends of the high-voltage port, and the positive electrode of the first charging interface is connected to the high-voltage DC bus through a relay; the method includes:

[0030] When it is determined that the low-voltage auxiliary battery and the power battery are both in a feeding state, and the power supply equipment for charging the vehicle transmits high voltage electricity through the first charging interface of the charging socket in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply equipment through the first charging interface of the charging socket into low voltage electricity to charge the low-voltage auxiliary battery.

[0031] In some embodiments, the first end of the two ends of the low-voltage port is connected to the positive electrode of the low-voltage auxiliary battery through a switch element, and the second end of the two ends of the low-voltage port is connected to the negative electrode of the low-voltage auxiliary battery; the positive electrode of the second charging interface of the charging socket is connected to the first connection point through a first unidirectional conductive element, and the negative electrode of the second charging interface of the charging socket is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port and the switch element, and the second connection point is the connection point between the second end of the low-voltage port and the negative electrode of the low-voltage auxiliary battery; the DC charging method also includes:

[0032] When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket, and both the low-voltage auxiliary battery and the power battery are in a feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

[0033] In some embodiments, the DC charging method further includes:

[0034] After determining that the bus capacitor on the high-voltage DC bus is pre-charged, a request message is sent to the power supply device, where the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode.

[0035] The DC charging circuit and DC charging method provided in the embodiments of the present application are configured such that a bidirectional DC converter is provided in the DC charging circuit, and the two ends of the low-voltage port of the bidirectional DC converter are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle, the two ends of the high-voltage port of the bidirectional DC converter are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle, the positive and negative electrodes of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at the two ends of the high-voltage port, and the positive electrode of the first charging interface is connected to the high-voltage DC bus through a relay, so that when the low-voltage auxiliary battery and the power battery of the vehicle are both in the feeding state, the high-voltage electricity transmitted by the power supply device through the first charging interface of the charging socket can be converted into low-voltage electricity by the bidirectional DC converter in the DC charging circuit to charge the low-voltage auxiliary battery, without using the power battery that has been fed to replenish the low-voltage auxiliary battery, so as to avoid deep discharge of the power battery due to the power battery replenishing the low-voltage auxiliary battery, thereby avoiding damage to the battery cell of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 One of the structural schematic diagrams of a DC charging circuit provided in an embodiment of the present application;

[0038] Figure 2 A second structural diagram of a DC charging circuit provided in an embodiment of the present application;

[0039] Figure 3 One of the power topology diagrams of a battery management controller provided in an embodiment of the present application;

[0040] Figure 4 A second schematic diagram of a power topology of a battery management controller provided in an embodiment of the present application;

[0041] Figure 5 A second structural diagram of a DC charging circuit provided in an embodiment of the present application;

[0042] Figure 6 A schematic diagram of a DC charging control guide circuit provided for related technologies;

[0043] Figure 7 A schematic diagram of a charging process in which a low-voltage auxiliary battery and a power battery are both in a feeding state provided in an embodiment of the present application;

[0044] Figure 8 One of the flow charts of a DC charging method provided in an embodiment of the present application;

[0045] Fig. 9 The second flowchart of a DC charging method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution 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. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] It should be noted that in the description of the embodiments of the present application, the terms "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0048] In order to facilitate a clearer understanding of the embodiments of the present application, some related technologies are first introduced as follows.

[0049] The low-voltage auxiliary battery in electric vehicles is also called a 12v battery or a 12v small battery. It plays a key role in new energy vehicles. Its main function is to drive various functions of the vehicle's electric motor, especially during the vehicle's starting and acceleration process, which requires the strong voltage it provides. The low-voltage auxiliary battery not only ensures the safe operation of the electric vehicle, but is also responsible for providing power for the vehicle's double flash, lights, instruments and central locks.

[0050] When the low-voltage auxiliary battery of an electric vehicle is out of power, it is necessary to recharge the low-voltage auxiliary battery before charging the power battery of the entire vehicle. One related technology is to recharge the low-voltage auxiliary battery first through an external power supply device, and then start the whole vehicle charging process after the low-voltage auxiliary battery is recharged to a certain level. This process requires external power supply equipment and waiting for recharging, and the after-sales cost is high and the efficiency is low. Another related technology is to recharge the low-voltage auxiliary battery through the power battery of an electric vehicle, and then start the whole vehicle charging process after the low-voltage auxiliary battery is recharged to a certain level. However, when the power battery and the low-voltage auxiliary battery are in the feeding state at the same time, recharging the low-voltage auxiliary battery through the power battery will cause the power battery to be deeply discharged, damaging the power battery cell.

[0051] Therefore, in order to overcome the defect that when the power battery and the low-voltage auxiliary battery are fed with power at the same time, replenishing the low-voltage auxiliary battery with the power battery will cause deep discharge of the power battery and damage the battery cells of the power battery, the embodiment of the present application provides a DC charging circuit and a DC charging method. The high voltage electricity transmitted by the power supply equipment is converted into low voltage electricity for charging the low-voltage auxiliary battery through a bidirectional DC converter in the DC charging circuit, without using the power battery that has been fed with power to replenish the low-voltage auxiliary battery. This can avoid deep discharge of the power battery caused by replenishing the low-voltage auxiliary battery with the power battery, thereby avoiding damage to the battery cells of the power battery.

[0052] In the following, in conjunction with the drawings in the embodiments of the present application, a DC charging circuit and a DC charging method provided in the embodiments of the present application are exemplarily introduced.

[0053] Figure 1 This is one of the structural diagrams of a DC charging circuit provided in an embodiment of the present application, such as Figure 1 As shown, it includes: a bidirectional DC converter 101, wherein the bidirectional DC converter 101 includes a low-voltage port 102 and a high-voltage port 103;

[0054] The two ends of the low-voltage port 102 are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery 104 of the vehicle;

[0055] The two ends of the high-voltage port 103 are respectively connected to the high-voltage DC bus 106 connected to the positive and negative electrodes of the power battery 105 of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket 107 of the vehicle are respectively connected to the high-voltage DC bus 106 at both ends of the high-voltage port 103, and the positive electrode of the first charging interface is connected to the high-voltage DC bus 106 through a relay;

[0056] The bidirectional DC converter 101 is used to: when the low-voltage auxiliary battery 104 and the power battery 105 are both in the feeding state, convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket 107 in a constant voltage mode or a constant current mode into low voltage electricity to charge the low-voltage auxiliary battery 104. The power supply device is a device used to charge the vehicle.

[0057] It should be noted that the power supply device in the embodiment of the present application may be a charging pile for charging the vehicle or any other device that can charge the vehicle.

[0058] It should be noted that the bidirectional DC converter (Direct Current-Direct Current converter, DCDC) can realize bidirectional energy transmission between two DC systems with different voltage levels. It can not only reduce the voltage, convert the DC voltage on the high voltage side into the voltage required by the low voltage side, but also increase the voltage, converting the DC voltage on the low voltage side into the voltage required by the high voltage side. This feature makes bidirectional DCDC particularly important in electric vehicles and hybrid vehicles, because the output voltage of the battery pack is low, while the motor requires a higher voltage drive. The bidirectional DCDC converter can adjust the voltage as needed to meet the needs of the motor.

[0059] It is understandable that based on Figure 1 In the DC charging circuit shown, when the low-voltage auxiliary battery 104 and the power battery 105 are both in the feeding state, the bidirectional DC converter 101 can convert the high-voltage electricity transmitted by the charging pile through the first charging interface of the charging socket 107 in a constant voltage mode or a constant current mode into low-voltage electricity to charge the low-voltage auxiliary battery 104.

[0060] It can be understood that when the charging pile transmits high voltage electricity through the first charging interface of the charging socket 107 in a constant voltage mode or a constant current mode, the relay at the positive end of the first charging interface of the charging socket 107 is in a closed state, so that the high voltage electricity transmitted by the charging pile through the first charging interface of the charging socket 107 can flow into the bidirectional DC converter 101 from the high voltage port 103 of the bidirectional DC converter 101 through the closed relay, and then the bidirectional DC converter 101 converts the incoming high voltage electricity into low voltage electricity and then flows out from the low voltage port 102 to the low voltage auxiliary battery 104, thereby charging the low voltage auxiliary battery 104.

[0061] It can be understood that in the embodiment of the present application, the first charging interface of the vehicle's charging socket 107 is an inflow interface for the high voltage electricity transmitted by the power supply device.

[0062] It should be noted that when the low-voltage auxiliary battery 104 is a lead-acid battery, the power supply equipment transmits high voltage electricity in a constant voltage mode; when the low-voltage auxiliary battery 104 is a lithium battery, the power supply equipment transmits high voltage electricity in a constant current mode.

[0063] It should be noted that the relay connected between the positive pole of the first charging interface of the charging socket 107 and the high-voltage DC bus 106 is a fast-charging relay. During the charging process, the fast-charging relay can quickly respond to the charging demand to ensure the stability and safety of the charging current. At the same time, after the charging is completed, the fast-charging relay can disconnect the power supply in time to prevent the equipment from being overcharged and damaged. The fast-charging relay can be controlled by a control chip, which can control the switch of the relay according to the changes in voltage and current, thereby realizing the control of the charging process.

[0064] It can be understood that the DC charging circuit provided in the embodiment of the present application is provided with a bidirectional DC converter in the DC charging circuit, and the two ends of the low-voltage port of the bidirectional DC converter are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle, and the two ends of the high-voltage port of the bidirectional DC converter are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle, and the positive and negative poles of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at both ends of the high-voltage port, and the positive pole of the first charging interface is connected to the high-voltage DC bus through a relay, so that when the low-voltage auxiliary battery and the power battery of the vehicle are both in the feeding state, the high-voltage electricity transmitted by the power supply equipment through the first charging interface of the charging socket can be converted into low-voltage electricity by the bidirectional DC converter in the DC charging circuit to charge the low-voltage auxiliary battery, without using the power battery that has been fed to replenish the low-voltage auxiliary battery, which can avoid deep discharge of the power battery due to the power battery replenishing the low-voltage auxiliary battery, thereby avoiding damage to the battery cell of the power battery.

[0065] Figure 2 The second structural diagram of a DC charging circuit provided in an embodiment of the present application is as follows: Figure 2 As shown, the first end of the two ends of the low-voltage port 102 is connected to the positive electrode of the low-voltage auxiliary battery 104 through a switch element 108, and the second end of the two ends of the low-voltage port 102 is connected to the negative electrode of the low-voltage auxiliary battery 104;

[0066] The positive pole of the second charging interface of the charging socket 107 is connected to the first connection point through the first unidirectional conductive element 109, and the negative pole of the second charging interface of the charging socket 107 is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port 102 and the switching element 108, and the second connection point is the connection point between the second end of the low-voltage port 102 and the negative pole of the low-voltage auxiliary battery 104.

[0067] In the embodiment of the present application, the bidirectional DC converter 101 is also used to convert the low voltage electricity transmitted by the power supply device through the second charging interface of the charging socket 107 into high voltage electricity to pre-charge the bus capacitor on the high voltage DC bus 106.

[0068] It should be noted that the switch element 108 may be a MOS tube or an insulated-gate bipolar transistor (IGBT) as a voltage-driven switch.

[0069] It should be noted that when the power supply device transmits low voltage electricity through the second charging interface of the charging socket 107, the switch element 108 is in an open state; and when the power supply device transmits high voltage electricity through the first charging interface of the charging socket 107, the switch element 108 is in a closed state.

[0070] It should be noted that the first unidirectional conductive element 109 may be a diode, a MOS tube or an insulated gate bipolar transistor IGBT, which can play a role of reverse voltage isolation through their unidirectional conductivity.

[0071] It should be noted that in order to prevent the relay from being damaged by excessive charging current, the bus capacitor of the high-voltage DC bus connected to the power battery needs to be pre-charged so that the voltage of the bus capacitor reaches a voltage value close to the power battery voltage. If not controlled, high current charging may cause the relay to burn out.

[0072] It is understandable that based on Figure 2 In the DC charging circuit shown, the power supply device can transmit low-voltage electricity through the second charging interface of the charging socket 107. The low-voltage electricity flows into the bidirectional DC converter 101 from the low-voltage port 102 of the bidirectional DC converter 101 through the first unidirectional conductive element 109, and then the bidirectional DC converter 101 converts the incoming low-voltage electricity into high-voltage electricity, which flows out from the high-voltage port 103 to the bus capacitor of the high-voltage DC bus 106. In this way, the bus capacitor of the high-voltage DC bus 106 is pre-charged, which can prevent the relay from being damaged by excessive charging current.

[0073] It is understandable that based on Figure 2 The DC charging circuit shown, when powered by the low-voltage auxiliary battery 104 , can utilize the 12V low-voltage electricity delivered by the charging pile through the second charging interface of the charging socket 107 to power the bidirectional DC converter 101 during the power-on process.

[0074] It can be understood that in the embodiment of the present application, the second charging interface of the vehicle's charging socket 107 is an inflow interface for the low-voltage electricity delivered by the power supply device.

[0075] In some embodiments, the DC charging circuit further includes a battery management controller (Battery Management System, BMS).

[0076] like Figure 3 As shown, the positive pole of the second charging interface of the charging socket 107 is connected to the battery management controller 110 through the first unidirectional conductive element 109; the positive pole of the low-voltage auxiliary battery 104 is connected to the battery management controller 110 through the second unidirectional conductive element 111; the battery management controller 110 is also connected to the connection point between the negative pole of the second charging interface of the charging socket 107 and the negative pole of the low-voltage auxiliary battery 104.

[0077] It should be noted that the second unidirectional conductive element 111 may be a diode, a MOS tube or an insulated gate bipolar transistor IGBT, which can play a role of reverse isolation through its unidirectional conductivity.

[0078] It is understandable that based on Figure 3 The power supply topology of the battery management controller shown can use the low-voltage auxiliary battery 104 to power the battery management controller 110, and can also use the low-voltage electricity transmitted by the charging pile through the second charging interface of the charging socket 107 to power the battery management controller 110, and the first unidirectional conductive element 109 and the second unidirectional conductive element 111 can prevent voltage backflow.

[0079] For example, Figure 4 A second schematic diagram of a power topology of a battery management controller provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, D1 and D2 are both diodes, which are equivalent to Figure 3 The first unidirectional conductive element 109 and the second unidirectional conductive element 111 in the charging socket are equivalent to A+ / A- Figure 3 The second charging interface of the charging socket 107 in the charging socket. When the low-voltage auxiliary battery supplies power to the battery management controller or the charging pile supplies power to the battery management controller through the A+ / A- of the charging socket, D1 and D2 can prevent voltage backflow.

[0080] In some embodiments, the battery management controller 110 is used to:

[0081] When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket 107, and the low-voltage auxiliary battery 104 and the power battery 105 are both in the feeding state, the bidirectional DC converter 101 is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket 107 into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus 106.

[0082] In an embodiment of the present application, when the charging gun is inserted into the charging socket 107 of the vehicle, the power supply equipment or the charging pile transmits 12V low-voltage electricity through the second charging interface of the charging socket 107. At this time, if the battery management controller 110 detects that the low-voltage auxiliary battery 104 and the power battery 105 of the vehicle are both in the feeding state, the bidirectional DC converter 101 is controlled to convert the low-voltage electricity transmitted by the power supply equipment or the charging pile through the second charging interface of the charging socket 107 into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus 106.

[0083] It can be understood that the embodiment of the present application controls the bidirectional DC converter 101 through the battery management controller 110, so that the bidirectional DC converter 101 converts the low-voltage electricity transmitted by the power supply equipment or the charging pile through the second charging interface of the charging socket 107 into high-voltage electricity, and then pre-charges the bus capacitor on the high-voltage DC bus 106, which can prevent the charging current from being too large and causing damage to the relay.

[0084] In some embodiments, the battery management controller 110 is further configured to:

[0085] After determining that the bus capacitor on the high-voltage DC bus 106 is pre-charged, sending a request message to the power supply device, the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode;

[0086] When it is determined that the power supply device transmits high voltage electricity through the first charging interface of the charging socket 107 in a constant voltage mode or a constant current mode, the bidirectional DC converter 101 is controlled to convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket 107 into low voltage electricity for charging the low voltage auxiliary battery 104.

[0087] In an embodiment of the present application, after determining that the bus capacitor on the high-voltage DC bus 106 is pre-charged, the battery management controller 110 sends a request message to the power supply device, and the request message can instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode. Furthermore, when it is determined that the power supply device transmits high voltage electricity in a constant voltage mode or a constant current mode through the first charging interface of the charging socket 107, the bidirectional DC converter 101 is controlled to convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket 107 into low voltage electricity to charge the low-voltage auxiliary battery 104.

[0088] In some embodiments, after the battery management controller 110 determines that the bus capacitor pre-charging on the high-voltage DC bus 106 is completed, if it is determined that the low-voltage auxiliary battery 104 is a lead-acid battery, it sends a first request message to the power supply device, and the first request message can instruct the power supply device to transmit high voltage electricity in a constant voltage mode; if it is determined that the low-voltage auxiliary battery 104 is a lithium battery, it sends a second request message to the power supply device, and the second request message can instruct the power supply device to transmit high voltage electricity in a constant current mode.

[0089] It can be understood that the embodiment of the present application pre-charges the bus capacitor on the high-voltage DC bus 106 first. After the pre-charging is completed, the battery management controller 110 requests the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode, and controls the bidirectional DC converter 101 to convert the high voltage electricity transmitted by the power supply device in a constant voltage mode or a constant current mode into low voltage electricity to charge the low-voltage auxiliary battery 104. This can not only prevent the excessive charging current from damaging the relay, but also convert the high voltage electricity provided by the power supply device into low voltage electricity to charge the low-voltage auxiliary battery 104, without using the power battery that has been powered to recharge the low-voltage auxiliary battery. This can avoid deep discharge of the power battery due to the power battery recharging the low-voltage auxiliary battery, thereby avoiding damage to the power battery cell.

[0090] In some embodiments, the battery management controller 110 is further configured to:

[0091] When it is determined that the power level of the low-voltage auxiliary battery 104 reaches a preset power level, an instruction message is sent to the power supply device, where the instruction message is used to instruct the power supply device to restart the charging process to charge the power battery 105 of the vehicle.

[0092] In an embodiment of the present application, when the battery management controller 110 controls the bidirectional DC converter 101 to convert the high voltage electricity transmitted by the power supply equipment into low voltage electricity to charge the low voltage auxiliary battery 104, if the battery management controller 110 determines that the power level of the low voltage auxiliary battery 104 reaches a preset power level, an indication message is sent to the power supply equipment. The indication message can instruct the power supply equipment to restart the charging process to charge the vehicle's power battery 105.

[0093] It should be noted that the preset power can be adaptively set based on actual applications, for example, calibrated according to the battery capacity and the low-voltage energy consumption of the whole vehicle, and the embodiments of the present application do not specifically limit this.

[0094] In some embodiments, in the charging process where the low-voltage auxiliary battery 104 and the power battery 105 are simultaneously powered, when the state of charge (SOC) or the remaining power percentage of the low-voltage auxiliary battery 104 reaches 10%, the battery management controller 110 instructs the power supply device to restart the charging process.

[0095] It can be understood that the embodiment of the present application utilizes the power supply equipment to first charge the vehicle's low-voltage auxiliary battery 104 until the power of the low-voltage auxiliary battery 104 reaches a preset power level, and then the battery management controller 110 instructs the power supply equipment to restart the charging process to charge the vehicle's power battery 105, which can effectively avoid the inability to perform DC charging of the vehicle due to simultaneous power supply from the low-voltage auxiliary battery 104 and the power battery 105.

[0096] In some embodiments, the bidirectional DC converter 101 further includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a first inductor, a second inductor, a first capacitor, a second capacitor and a transformer; the high voltage side of the transformer includes a first terminal and a second terminal, and the low voltage side of the transformer includes a third terminal, a fourth terminal and a fifth terminal;

[0097] The first MOS transistor and the second MOS transistor are connected in series to form a first series branch, the third MOS transistor and the fourth MOS transistor are connected in series to form a second series branch, the first series branch and the second series branch are connected in parallel, and both ends of the first series branch are both ends of the high-voltage port;

[0098] One end of the first inductor is connected to the connection line between the first MOS transistor and the second MOS transistor, and the other end of the first inductor is connected to the first terminal;

[0099] One end of the first capacitor is connected to the connection line between the third MOS transistor and the fourth MOS transistor, and the other end of the first capacitor is connected to the second terminal;

[0100] One end of the fifth MOS tube is connected to the third terminal, one end of the sixth MOS tube is connected to the fourth terminal, and the other end of the fifth MOS tube is connected to the other end of the sixth MOS tube;

[0101] One end of the second inductor is connected to the fifth terminal, the other end of the second inductor is connected to one end of the second capacitor, the other end of the second capacitor is connected to the other end of the sixth MOS tube, and both ends of the second capacitor are both ends of the low-voltage port.

[0102] For example, Figure 5The second structural diagram of a DC charging circuit provided in an embodiment of the present application is as follows: Figure 5 As shown, the bidirectional DC converter is composed of MOS tubes Q1, Q2, Q3, Q4, Q5, Q6, transformer M1, capacitors C1, C2, inductors L1 and L2. Q1, Q2, Q3, Q4, Q5, Q6 correspond to the first MOS tube, the second MOS tube, the third MOS tube, the fourth MOS tube, the fifth MOS tube and the sixth MOS tube in the embodiment of the present application, respectively, capacitors C1 and C2 correspond to the first capacitor and the second capacitor in the embodiment of the present application, respectively, and inductors L1 and L2 correspond to the first inductor and the second inductor in the embodiment of the present application, respectively. Transformer M1 can realize electrical isolation and transformation ratio adjustment, and realize the bidirectional flow of electric energy through pulse width modulation and frequency modulation.

[0103] It is understandable that based on Figure 5 The bidirectional DC converter in the DC charging circuit shown or the bidirectional DC converter provided in the embodiment of the present application can not only convert the high voltage electricity of the power battery into 12V low voltage electricity to charge the low voltage auxiliary battery, but also convert the 12V low voltage electricity of the low voltage auxiliary battery into high voltage electricity.

[0104] Figure 6 A schematic diagram of a DC charging control guide circuit provided for related technology, such as Figure 6 As shown, the vehicle interface (equivalent to the charging socket in the embodiment of the present application) is connected to the battery pack of the electric vehicle (equivalent to the power battery in the embodiment of the present application) through relays K5 and K6, so that the power supply device can transmit electricity to the battery pack of the electric vehicle through the vehicle interface to charge the battery pack. After the vehicle interface is fully connected, closing relays K3 and K4 can turn on the low-voltage auxiliary power supply circuit. Figure 6 It can be seen from the circuit shown that when the battery pack and the auxiliary power supply (equivalent to the low-voltage auxiliary battery in the embodiment of the present application) of the electric vehicle are powered at the same time, it is impossible to convert the high-voltage electricity transmitted by the power supply device through the vehicle interface into low-voltage electricity to charge the auxiliary power supply. It should be noted that the 12v low-voltage electricity transmitted by the power supply device or the charging pile cannot charge the low-voltage auxiliary battery. The reason is that the power of the 12v low-voltage electricity output by the power supply device or the charging pile is very small, which is not enough to charge the low-voltage auxiliary battery. Only when the power supply device or the charging pile outputs high-voltage electricity, because the power corresponding to the high-voltage electricity is relatively large, the low-voltage auxiliary battery can be charged only after the high-voltage electricity output by the power supply device or the charging pile is converted into low-voltage electricity.

[0105] For example, Figure 7 A schematic diagram of a charging process in which both a low-voltage auxiliary battery and a power battery are in a feeding state is provided in an embodiment of the present application, such as Figure 7As shown in the figure, after the charging gun is inserted into the charging socket of the vehicle, the 12V power supply is input through the A+ / A- of the charging socket (equivalent to the positive and negative poles of the second charging interface of the charging socket mentioned above) to power the BMS and the bidirectional DCDC; if the BMS detects that the vehicle's 12V small battery and power battery are feeding at the same time, the low-voltage to high-voltage function of the bidirectional DCDC is started to pre-charge the bus capacitor on the high-voltage DC bus; then, after the BMS confirms that the charging pile has completed insulation monitoring and voltage discharge, the BMS notifies the charging pile that the vehicle-end high-voltage charging circuit has been closed (at this time, the voltage of the bus capacitor is actually used to simulate the closure of the vehicle-end high-voltage charging circuit). When the charging pile outputs a constant voltage or a constant current, the BMS starts the high-voltage-to-low-voltage function of the bidirectional DCDC to charge the 12v small battery. When it is determined that the power of the 12v small battery has reached the preset power level (ensuring that the 12v small battery has the energy required to complete the charging startup process of the whole vehicle), the BMS instructs the charging pile to restart the charging process to charge the power battery of the whole vehicle.

[0106] It is understandable that the embodiment of the present application uses the 12V power supply output by the charging pile to power the BMS and the bidirectional DCDC. When it is detected that the 12V small battery and the power battery are feeding power at the same time, the BMS requests the charging pile to deliver high voltage electricity in constant voltage or constant current mode. The bidirectional DCDC converts the high voltage electricity delivered by the charging pile into 12V low voltage to charge the 12V small battery. When the power of the 12V small battery reaches the preset power, the charging pile restarts the charging process to charge the power battery of the whole vehicle, which can effectively improve the reliability of the whole vehicle charging. The embodiment of the present application can at least achieve the following beneficial effects:

[0107] (1) Avoid the inability to perform DC charging due to the simultaneous power supply of the 12V small battery and the power battery.

[0108] (2) The 12V small battery can be charged without the need for an external power supply device, making charging more convenient and improving the user experience.

[0109] (3) The 12V power supply input from the charging pile through the A+ / A- of the vehicle's charging socket is used to pre-charge the high-voltage DC bus, which can avoid discharge of the battery pack during the pre-charging process.

[0110] (5) Restarting the charging process after the 12V small battery reaches the preset charge level can avoid charging start failure due to insufficient low-voltage power supply and enhance the reliability of the charging start process.

[0111] The DC charging method provided in the embodiment of the present application is introduced below.

[0112] It should be noted that the DC charging method provided in the embodiment of the present application is applied to a vehicle including the DC charging circuit provided in the above embodiment, and the circuit structure of the DC charging circuit is as follows: Figure 1 As shown, it includes a bidirectional DC converter 101, and the bidirectional DC converter 101 includes a low-voltage port 102 and a high-voltage port 103; the two ends of the low-voltage port 102 are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery 104 of the vehicle; the two ends of the high-voltage port 103 are respectively connected to the high-voltage DC bus 106 connected to the positive and negative electrodes of the power battery 105 of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket 107 of the vehicle are respectively connected to the high-voltage DC bus 106 at both ends of the high-voltage port 103, and the positive electrode of the first charging interface is connected to the high-voltage DC bus 106 through a relay.

[0113] Figure 8 One of the flow charts of a DC charging method provided in an embodiment of the present application is as follows: Figure 8 As shown, the method includes:

[0114] S801. When it is determined that both the low-voltage auxiliary battery and the power battery are in a feeding state, and the power supply device for charging the vehicle transmits high voltage electricity through the first charging interface of the charging socket in a constant voltage mode or a constant current mode, control the bidirectional DC converter to convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket into low voltage electricity to charge the low-voltage auxiliary battery.

[0115] It should be noted that the executor of the DC charging method provided in the embodiment of the present application can be a battery management controller BMS in a vehicle, or other electronic devices. The electronic device can be a mobile electronic device or a non-mobile electronic device, and the electronic device can communicate electrically and / or wirelessly with the charging pile and the bidirectional DC converter in the vehicle.

[0116] In an embodiment of the present application, if it is determined that the vehicle's low-voltage auxiliary battery and power battery are both in a feeding state, and the power supply equipment used to charge the vehicle transmits high voltage electricity through the first charging interface of the vehicle's charging socket in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply equipment through the first charging interface of the charging socket into low voltage electricity to charge the vehicle's low-voltage auxiliary battery.

[0117] It should be noted that the power supply device in the embodiment of the present application may be a charging pile for charging the vehicle or any other device that can charge the vehicle.

[0118] It can be understood that the DC charging method provided in the embodiment of the present application, when it is determined that the low-voltage auxiliary battery and the power battery of the vehicle are both in the feeding state, controls the bidirectional DC converter to convert the high-voltage electricity transmitted by the power supply equipment through the first charging interface of the charging socket into low-voltage electricity to charge the low-voltage auxiliary battery, without using the power battery that has been fed to recharge the low-voltage auxiliary battery. This can avoid deep discharge of the power battery due to recharging the low-voltage auxiliary battery by the power battery, thereby avoiding damage to the power battery cells.

[0119] In some embodiments, Figure 2 As shown, the first end of the two ends of the low-voltage port 102 is connected to the positive electrode of the low-voltage auxiliary battery 104 through a switch element 108, and the second end of the two ends of the low-voltage port 102 is connected to the negative electrode of the low-voltage auxiliary battery 104; the positive electrode of the second charging interface of the charging socket 107 is connected to the first connection point through the first unidirectional conductive element 109, and the negative electrode of the second charging interface of the charging socket 107 is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port 102 and the switch element 108, and the second connection point is the connection point between the second end of the low-voltage port 102 and the negative electrode of the low-voltage auxiliary battery 104.

[0120] In some embodiments, the DC charging method further includes:

[0121] When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket, and both the low-voltage auxiliary battery and the power battery are in a feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

[0122] In an embodiment of the present application, if it is determined that the power supply device transmits low-voltage electricity through the charging socket, and the low-voltage auxiliary battery and the power battery are both in the feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity and then pre-charge the bus capacitor on the high-voltage DC bus, thereby preventing the charging current from being excessive and causing damage to the positive relay.

[0123] In some embodiments, the DC charging method further includes:

[0124] After determining that the bus capacitor on the high-voltage DC bus is pre-charged, a request message is sent to the power supply device, where the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode.

[0125] In an embodiment of the present application, if it is determined that the bus capacitor on the high-voltage DC bus is pre-charged, a request message is sent to the power supply device, and the request message can instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode. Then, when it is determined that the power supply device transmits high voltage electricity in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply device into low voltage electricity to charge the low-voltage auxiliary battery.

[0126] In some embodiments, after determining that the bus capacitor on the high-voltage DC bus is pre-charged, a request message is sent to the power supply device, including: after determining that the bus capacitor on the high-voltage DC bus is pre-charged, if it is determined that the low-voltage auxiliary battery is a lead-acid battery, a first request message is sent to the power supply device, and the first request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode; if it is determined that the low-voltage auxiliary battery is a lithium battery, a second request message is sent to the power supply device, and the second request message is used to instruct the power supply device to transmit high voltage electricity in a constant current mode.

[0127] It can be understood that the embodiment of the present application sends a request message to the power supply device after determining that the pre-charging of the bus capacitor on the high-voltage DC bus is completed. The request message can instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode. Then, when it is determined that the power supply device transmits high voltage electricity in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply device into low voltage electricity to charge the low-voltage auxiliary battery. This can not only prevent the positive relay from being damaged by excessive charging current, but also convert the high voltage electricity provided by the power supply device into low voltage electricity to charge the low-voltage auxiliary battery. There is no need to use the power battery that has been powered to recharge the low-voltage auxiliary battery, which can avoid deep discharge of the power battery due to the power battery recharging the low-voltage auxiliary battery, thereby avoiding damage to the power battery cell.

[0128] In some embodiments, the DC charging method further includes:

[0129] When it is determined that the power level of the low-voltage auxiliary battery reaches a preset power level, an instruction message is sent to the power supply device, where the instruction message is used to instruct the power supply device to restart the charging process to charge the power battery of the vehicle.

[0130] In an embodiment of the present application, when the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply equipment into low voltage electricity to charge the low voltage auxiliary battery, if it is determined that the power level of the low voltage auxiliary battery has reached a preset power level, an indication message is sent to the power supply equipment. The indication message can instruct the power supply equipment to restart the charging process to charge the vehicle's power battery.

[0131] It should be noted that the preset power can be adaptively set based on actual applications, for example, calibrated according to the battery capacity and the low-voltage energy consumption of the whole vehicle, and the embodiments of the present application do not specifically limit this.

[0132] For example, Fig. 9 A second flow chart of a DC charging method provided in an embodiment of the present application is shown in FIG. Fig. 9 As shown, the method includes:

[0133] S901. When it is determined that the power supply device transmits low-voltage electricity through the charging socket and the low-voltage auxiliary battery and the power battery are both in a feeding state, control the bidirectional DC converter to convert the low-voltage electricity transmitted by the power supply device into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

[0134] S902: After determining that the bus capacitor on the high-voltage DC bus is pre-charged, send a request message to the power supply device, where the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode.

[0135] S903: When it is determined that the power supply device transmits high voltage electricity through the charging socket in a constant voltage mode or a constant current mode, control the bidirectional DC converter to convert the high voltage electricity transmitted by the power supply device into low voltage electricity to charge the low voltage auxiliary battery.

[0136] S904. When it is determined that the power level of the low-voltage auxiliary battery reaches a preset power level, an instruction message is sent to the power supply device, where the instruction message is used to instruct the power supply device to restart the charging process to charge the power battery of the vehicle.

[0137] It can be understood that the embodiment of the present application controls the bidirectional DC converter to convert the low voltage electricity transmitted by the power supply equipment into high voltage electricity to pre-charge the bus capacitor on the high voltage DC bus after determining that the power supply equipment starts to transmit low voltage electricity through the charging socket of the vehicle, and the low voltage auxiliary battery and the power battery of the vehicle are both in the feeding state, and then instructs the power supply equipment to transmit high voltage electricity in a constant voltage mode or a constant current mode after determining that the pre-charging of the bus capacitor on the high voltage DC bus is completed, and controls the bidirectional DC converter to convert the high voltage electricity transmitted by the power supply equipment into low voltage electricity to charge the low voltage auxiliary battery. There is no need to use the power battery that has been fed to replenish the low voltage auxiliary battery, which can avoid deep discharge of the power battery due to the power battery replenishing the low voltage auxiliary battery, thereby avoiding damage to the power battery cell. Further, when it is determined that the power of the low voltage auxiliary battery reaches the preset power, the power supply equipment is instructed to restart the charging process to charge the power battery of the vehicle, which can effectively improve the reliability of the charging of the whole vehicle and avoid the inability to perform DC charging of the vehicle due to the feeding of power by the low voltage auxiliary battery and the power battery.

[0138] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, part or all of the steps in the DC charging method provided in the above embodiments are implemented.

[0139] An embodiment of the present application also provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are executed by a processor, some or all of the steps in the DC charging method provided in the above embodiments are implemented.

[0140] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

[0141] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the embodiments of the present application may adopt the form of hardware embodiments, software embodiments, or embodiments in combination with software and hardware. Moreover, the embodiments of the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) that contain computer-usable program code.

[0142] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0143] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0144] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0145] The above description is merely an optional embodiment of the present application and is not intended to limit the protection scope of the present application.

Claims

1. A DC charging circuit, characterized in that: include: A bidirectional DC converter, the bidirectional DC converter comprising a low voltage port and a high voltage port; The two ends of the low-voltage port are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle; The two ends of the high-voltage port are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at the two ends of the high-voltage port, and the positive electrode of the first charging interface is connected to the high-voltage DC bus through a relay; The bidirectional DC converter is used to: when the low-voltage auxiliary battery and the power battery are both in a feeding state, convert the high-voltage electricity transmitted by the power supply device through the first charging interface of the charging socket in a constant voltage mode or a constant current mode into low-voltage electricity to charge the low-voltage auxiliary battery. The power supply device is a device used to charge the vehicle.

2. The DC charging circuit according to claim 1, characterized in that: A first end of the two ends of the low-voltage port is connected to the positive electrode of the low-voltage auxiliary battery through a switch element, and a second end of the two ends of the low-voltage port is connected to the negative electrode of the low-voltage auxiliary battery; The positive electrode of the second charging interface of the charging socket is connected to the first connection point through the first unidirectional conductive element, and the negative electrode of the second charging interface of the charging socket is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port and the switching element, and the second connection point is the connection point between the second end of the low-voltage port and the negative electrode of the low-voltage auxiliary battery; The bidirectional DC converter is also used to convert the low voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high voltage electricity to pre-charge the bus capacitor on the high voltage DC bus.

3. The DC charging circuit according to claim 2, characterized in that: The DC charging circuit also includes a battery management controller; The positive electrode of the second charging interface of the charging socket is connected to the battery management controller through the first unidirectional conductive element; The positive electrode of the low-voltage auxiliary battery is connected to the battery management controller via a second unidirectional conductive element; The battery management controller is also connected to a connection point between the negative electrode of the second charging interface of the charging socket and the negative electrode of the low-voltage auxiliary battery.

4. The DC charging circuit according to claim 3, characterized in that: The battery management controller is used for: When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket, and both the low-voltage auxiliary battery and the power battery are in a feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

5. The DC charging circuit according to claim 4, characterized in that: The battery management controller is also used for: After determining that the bus capacitor on the high-voltage DC bus is pre-charged, sending a request message to the power supply device, the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode; When it is determined that the power supply device transmits high voltage electricity through the first charging interface of the charging socket in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply device through the first charging interface of the charging socket into low voltage electricity for charging the low voltage auxiliary battery.

6. The DC charging circuit according to claim 5, characterized in that: The battery management controller is also used for: When it is determined that the power level of the low-voltage auxiliary battery reaches a preset power level, an instruction message is sent to the power supply device, where the instruction message is used to instruct the power supply device to restart the charging process to charge the power battery of the vehicle.

7. The DC charging circuit according to any one of claims 1 to 6, characterized in that: The bidirectional DC converter further includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a sixth MOS transistor, a first inductor, a second inductor, a first capacitor, a second capacitor and a transformer; the high voltage side of the transformer includes a first terminal and a second terminal, and the low voltage side of the transformer includes a third terminal, a fourth terminal and a fifth terminal; The first MOS transistor and the second MOS transistor are connected in series to form a first series branch, the third MOS transistor and the fourth MOS transistor are connected in series to form a second series branch, the first series branch and the second series branch are connected in parallel, and both ends of the first series branch are both ends of the high-voltage port; One end of the first inductor is connected to the connection line between the first MOS transistor and the second MOS transistor, and the other end of the first inductor is connected to the first terminal; One end of the first capacitor is connected to the connection line between the third MOS transistor and the fourth MOS transistor, and the other end of the first capacitor is connected to the second terminal; One end of the fifth MOS tube is connected to the third terminal, one end of the sixth MOS tube is connected to the fourth terminal, and the other end of the fifth MOS tube is connected to the other end of the sixth MOS tube; One end of the second inductor is connected to the fifth terminal, the other end of the second inductor is connected to one end of the second capacitor, the other end of the second capacitor is connected to the other end of the sixth MOS tube, and both ends of the second capacitor are both ends of the low-voltage port.

8. A DC charging method, characterized in that: Applicable to a vehicle including a DC charging circuit, the DC charging circuit including a bidirectional DC converter, the bidirectional DC converter including a low-voltage port and a high-voltage port; the two ends of the low-voltage port are respectively connected to the positive and negative electrodes of the low-voltage auxiliary battery of the vehicle; the two ends of the high-voltage port are respectively connected to the high-voltage DC bus connected to the positive and negative electrodes of the power battery of the vehicle; the positive and negative electrodes of the first charging interface of the charging socket of the vehicle are respectively connected to the high-voltage DC bus at the two ends of the high-voltage port, and the positive electrode of the first charging interface is connected to the high-voltage DC bus through a relay; the method includes: When it is determined that the low-voltage auxiliary battery and the power battery are both in a feeding state, and the power supply equipment for charging the vehicle transmits high voltage electricity through the first charging interface of the charging socket in a constant voltage mode or a constant current mode, the bidirectional DC converter is controlled to convert the high voltage electricity transmitted by the power supply equipment through the first charging interface of the charging socket into low voltage electricity to charge the low-voltage auxiliary battery.

9. The DC charging method according to claim 8, characterized in that: The first end of the two ends of the low-voltage port is connected to the positive electrode of the low-voltage auxiliary battery through a switch element, and the second end of the two ends of the low-voltage port is connected to the negative electrode of the low-voltage auxiliary battery; the positive electrode of the second charging interface of the charging socket is connected to the first connection point through a first unidirectional conductive element, and the negative electrode of the second charging interface of the charging socket is connected to the second connection point; the first connection point is the connection point between the first end of the low-voltage port and the switch element, and the second connection point is the connection point between the second end of the low-voltage port and the negative electrode of the low-voltage auxiliary battery; the method also includes: When it is determined that the power supply device transmits low-voltage electricity through the second charging interface of the charging socket, and both the low-voltage auxiliary battery and the power battery are in a feeding state, the bidirectional DC converter is controlled to convert the low-voltage electricity transmitted by the power supply device through the second charging interface of the charging socket into high-voltage electricity to pre-charge the bus capacitor on the high-voltage DC bus.

10. The DC charging method according to claim 9, characterized in that: The method further comprises: After determining that the bus capacitor on the high-voltage DC bus is pre-charged, a request message is sent to the power supply device, where the request message is used to instruct the power supply device to transmit high voltage electricity in a constant voltage mode or a constant current mode.

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