Power battery charging system and vehicle

Abstract

The invention relates to a power battery charging system and a vehicle. The power battery charging system comprises N alternating current charging loops, N is greater than or equal to 2, and each alternating current charging loop comprises an alternating current charging port (11) used for being connected with an alternating current charging gun; the AC-DC converter (12) is connected with the alternating current charging port and used for converting alternating current input by the alternating current charging port into direct current; the first voltage converter (13) is respectively connected with the AC-DC converter and the power battery and is used for converting the direct current output by the AC-DC converter into voltage and inputting the voltage into the power battery (10) to charge the power battery; the AC-DC converters and the first voltage converters in the N AC charging loops are integrated in the same vehicle-mounted charger (20). Therefore, the AC-DC converters and the first voltage converters in the plurality of AC charging loops can share a control module, a cooling loop, a shell, a high-voltage wiring harness and other devices in the vehicle-mounted charger, the implementation cost of multi-path AC charging is reduced, and meanwhile, the expansion of the AC charging loops is also facilitated.

Description

Technical Field

[0001] The present disclosure relates to the field of vehicles, and in particular, to a power battery charging system and a vehicle. Background Art

[0002] With the popularity of new energy electric vehicles, the fast charging technology of electric vehicles has become a hot topic of research. In order to solve the problem of fast charging, some vehicles are equipped with two DC charging ports, which can support two DC charging guns to charge the power battery of the same vehicle at the same time, so as to achieve fast charging. Summary of the invention

[0003] An object of the present disclosure is to provide a power battery charging system and a vehicle capable of fast charging.

[0004] In order to achieve the above object, the present disclosure provides a power battery charging system, wherein the power battery charging system includes N AC charging circuits, N≥2, and each AC charging circuit includes:

[0005] AC charging port, used to connect an AC charging gun;

[0006] An AC-DC converter connected to the AC charging port and used to convert the AC power input by the AC charging port into DC power;

[0007] A first voltage converter, connected to the AC-DC converter and the power battery, respectively, for converting the direct current output by the AC-DC converter into a voltage and inputting the voltage into the power battery to charge the power battery;

[0008] The AC-DC converters and the first voltage converter in the N AC charging circuits are integrated in the same on-board charger.

[0009] Optionally, the N AC charging circuits include N AC-DC converters corresponding to each AC charging circuit one by one, and the N AC charging circuits share the same first voltage converter.

[0010] Optionally, the AC-DC converter is a PFC, and the first voltage converter is an LLC or CLLC resonant converter.

[0011] Optionally, the AC-DC converter includes a first inductor, a second inductor, a first group of switch tubes, a second group of switch tubes and a third group of switch tubes, and each group of switch tubes includes two switch tubes connected in series;

[0012] The positive input end of the AC-DC converter is divided into a first branch and a second branch, the first branch is connected to the middle node of the first group of switch tubes through the first inductor, the second branch is connected to the middle node of the second group of switch tubes through the second inductor, the negative input end of the AC-DC converter is connected to the middle node of the third group of switch tubes, the first end of each group of switch tubes is connected in common and serves as the first output end of the AC-DC converter, and the second end of each group of switch tubes is connected in common and serves as the second output end of the AC-DC converter.

[0013] Optionally, the first voltage converter includes a transformer, a third inductor, a fourth inductor, a fifth capacitor, a sixth capacitor, a fourth group of switch tubes, a fifth group of switch tubes, a sixth group of switch tubes and a seventh group of switch tubes, each group of switch tubes includes two switch tubes connected in series;

[0014] The first end of the first side of the transformer is connected to the middle node of the fourth group of switch tubes through the third inductor and the fifth capacitor in sequence, the second end of the first side of the transformer is connected to the middle node of the fifth group of switch tubes, the first end of the second side of the transformer is connected to the middle node of the sixth group of switch tubes, and the second end of the second side of the transformer is connected to the middle node of the seventh group of switch tubes through the fourth inductor and the sixth capacitor in sequence;

[0015] The first end of the fourth group of switch tubes and the first end of the fifth group of switch tubes are connected together and serve as the positive input end of the first voltage converter, and the second end of the fourth group of switch tubes and the second end of the fifth group of switch tubes are connected together and serve as the negative input end of the first voltage converter;

[0016] The first end of the sixth group of switch tubes and the first end of the seventh group of switch tubes are connected together and serve as the positive output end of the first voltage converter. The second end of the sixth group of switch tubes and the second end of the seventh group of switch tubes are connected together and serve as the negative output end of the first voltage converter.

[0017] Optionally, the power battery charging system further includes M DC charging circuits, where M≥1.

[0018] Optionally, at least one DC charging circuit among the M DC charging circuits includes:

[0019] DC charging port, used to connect a DC charging gun;

[0020] The second voltage converter is connected to the DC charging gun and the power battery respectively, and is used to convert the DC power input from the DC charging port into a voltage and then input it into the power battery to charge the power battery.

[0021] Optionally, the second voltage converter multiplexes a bridge arm in a motor controller and a coil in a drive motor.

[0022] Optionally, two DC charging circuits among the M DC charging circuits respectively reuse two drive systems in the vehicle, and each drive system includes a motor controller and a drive motor.

[0023] Optionally, the positive pole of the DC charging port is connected to the center point of the coil in the motor, the first bus terminal of the bridge arm in the motor controller is connected to the positive pole of the power battery, and the second bus terminal of the bridge arm in the motor controller is respectively connected to the negative pole of the power battery and the negative pole of the DC charging port.

[0024] Optionally, the second voltage converter includes a first bridge arm and a fifth inductor, the positive pole of the DC charging port is connected to the midpoint of the first bridge arm through the fifth inductor, the first end of the first bridge arm is connected to the positive pole of the power battery, and the second end of the first bridge arm is respectively connected to the negative pole of the power battery and the negative pole of the DC charging port.

[0025] The present disclosure also provides a vehicle, including a power battery and the power battery charging system provided by the present disclosure.

[0026] Through the above technical solution, the power battery charging system includes N AC charging circuits, which can realize AC charging of power batteries by multiple AC guns at the same time, thereby improving the AC charging power. In addition, the AC-DC converters and the first voltage converter in the N AC charging circuits are integrated in the same on-board charger, so that the AC-DC converters and the first voltage converter in the multiple AC charging circuits can share the control module, cooling circuit, housing, high-voltage wiring harness and other components in the on-board charger, thereby reducing the implementation cost of multi-channel AC charging and facilitating the expansion of AC charging circuits.

[0027] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0029] Figure 1 It is a schematic structural diagram of a power battery charging system provided by an exemplary embodiment.

[0030] Figure 2 It is a structural schematic diagram of a power battery charging system provided by another exemplary embodiment.

[0031] Figure 3It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment.

[0032] Figure 4 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment.

[0033] Figure 5 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment.

[0034] Figure 6 and Figure 7 yes Figure 5 Schematic diagram of current flow during charging in one DC charging circuit.

[0035] Figure 8 yes Figure 5 A schematic diagram of current flow when one DC charging circuit and one AC charging circuit are charged simultaneously in an embodiment.

[0036] Fig. 9 yes Figure 5 Schematic diagram of current flow when one DC charging circuit and three AC charging circuits are charged simultaneously in an embodiment.

[0037] Fig.10 yes Figure 5 Schematic diagram of current flow when three DC charging circuits and three AC charging circuits are charged simultaneously in an embodiment.

[0038] Fig.11 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment.

[0039] Fig.12 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment.

[0040] Fig.13 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment. DETAILED DESCRIPTION

[0041] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0042] Figure 1 FIG. 1 is a schematic diagram of a power battery charging system provided by an exemplary embodiment. Figure 1As shown, the power battery charging system includes N AC charging circuits, where N≥2. Each AC charging circuit includes an AC charging port 11 , an AC-DC (Alternating Current-Direct Current) converter 12 and a first voltage converter 13 .

[0043] The AC charging port 11 is used to connect an AC charging gun. The AC-DC converter 12 is connected to the AC charging port and is used to convert the AC power input from the AC charging port into DC power. The first voltage converter 13 is connected to the AC-DC converter and the power battery respectively and is used to convert the DC power output from the AC-DC converter into a voltage and input it into the power battery 10 to charge the power battery.

[0044] The AC-DC converters and the first voltage converter in the N AC charging circuits are integrated in the same on-board charger 20 .

[0045] The power battery charging system may also include one or more controllers, which can interact with the charging pile through the charging subnet via CAN signals, and control each stage of AC charging and the contactor in the AC charging circuit. One or more controllers may be set in the battery management system (Battery Management System, BMS). If not set in the BMS, one or more controllers may interact with the BMS for signals, such as AC charging gun connection signal, AC charging confirmation signal, high-voltage main circuit power up and down request, insulation monitoring command request, etc. The BMS can monitor the power battery cell status (such as single cell voltage, temperature, maximum allowable charging current, etc.) and calculate the nuclear power state (State of Charge, SOC) during the DC / AC charging process. When the power battery charging conditions are not met, one or more controllers can terminate the DC charging control. One or more controllers can interact with the first voltage converter 13 for signals, such as the working command, target voltage and current value of the first voltage converter 13. After receiving the working command and the working target voltage and current value, the first voltage converter 13 controls the output of the corresponding voltage and current value and feeds back its own state.

[0046] The on-board charger 20 is an on-board charger with AC charging function, which can be one or more assemblies. When the on-board charger 20 is an independent assembly, it can include a multi-channel AC-DC converter 12 to perform AC / DC conversion, convert the AC power input from the power grid into DC power, and then use the first voltage converter 13 to perform DC / DC conversion to adjust the charging voltage required by the power battery.

[0047] Through the above technical solution, the power battery charging system includes N AC charging circuits, which can realize AC charging of power batteries by multiple AC guns at the same time, thereby improving the AC charging power. In addition, the AC-DC converters and the first voltage converter in the N AC charging circuits are integrated in the same on-board charger, so that the AC-DC converters and the first voltage converter in the multiple AC charging circuits can share the control module, cooling circuit, housing, high-voltage wiring harness and other components in the on-board charger, thereby reducing the implementation cost of multi-channel AC charging and facilitating the expansion of AC charging circuits.

[0048] The AC-DC converter 12 may be a power factor corrector (PFC), and the first voltage converter 13 may be an LLC resonant converter or a CLLC resonant converter.

[0049] Figure 2 FIG. 1 is a schematic diagram of a power battery charging system provided by another exemplary embodiment. Figure 2 As shown, the AC-DC converter 12 may include a first inductor, a second inductor, a first group of switch tubes, a second group of switch tubes, and a third group of switch tubes, each group of switch tubes including two switch tubes connected in series ( Figure 2 MOS tube is shown in the figure). The positive input terminal of the AC-DC converter 12 is divided into two branches, the first branch and the second branch. The first branch is connected to the middle node of the first group of switch tubes (M1, M2) through the first inductor L1, and the second branch is connected to the middle node of the second group of switch tubes (M3, M4) through the second inductor L2. The negative input terminal of the AC-DC converter 12 is connected to the middle node of the third group of switch tubes (M5, M6). The first end of each group of switch tubes is connected in common and serves as the first output end (for example, the positive output end) of the AC-DC converter 12, and the second end of each group of switch tubes is connected in common and serves as the second output end (for example, the positive output end) of the AC-DC converter 12. Among them, the switch tubes (M1, M2, M3, M4) connected to the first inductor and the second inductor work in the first timing sequence, and the switch tubes (M5, M6) not connected to the first inductor and the second inductor work in the second timing sequence.

[0050] Figure 2 In the embodiment, the first voltage converter 13 is a CLLC resonant converter. The first voltage converter 13 includes a transformer, a third inductor L3, a fourth inductor L4, a fifth capacitor L5, a sixth capacitor L6, a fourth group of switch tubes, a fifth group of switch tubes, a sixth group of switch tubes, and a seventh group of switch tubes. An inductor, a capacitor, and two groups of switch tubes are provided on each side of the transformer. In the fourth group of switch tubes, the fifth group of switch tubes, the sixth group of switch tubes, and the seventh group of switch tubes, each group of switch tubes includes two switch tubes connected in series ( Figure 2 MOS tube is shown in the figure).

[0051] The first end of the first side of the transformer is connected to the middle node of the fourth group of switch tubes (M9, M10) through the third inductor L3 and the fifth capacitor C5 in sequence, and the second end of the first side of the transformer is connected to the middle node of the fifth group of switch tubes (M7, M8). The first end of the second side of the transformer is connected to the middle node of the sixth group of switch tubes (M11, M12), and the second end of the second side of the transformer is connected to the middle node of the seventh group of switch tubes (M13, M14) through the fourth inductor L4 and the sixth capacitor C6 in sequence.

[0052] The first end of each group of switch tubes in the two groups of switch tubes (the fourth group of switch tubes and the fifth group of switch tubes) on the first side of the transformer is connected in common and serves as the positive input end of the first voltage converter 13, and the second end of each group of switch tubes is connected in common and serves as the negative input end of the first voltage converter 13.

[0053] The first end of each group of switch tubes in the two groups of switch tubes (the sixth group of switch tubes and the seventh group of switch tubes) on the second side of the transformer is connected in common and serves as the positive output end of the first voltage converter 13, and the second end of each group of switch tubes is connected in common and serves as the negative output end of the first voltage converter 13.

[0054] Among them, the switch tubes M7, M8, M9 and M10 are used to adjust the duty cycle by controlling on and off, thereby adjusting the voltage of the input transformer. The switch tubes M11, M12, M13 and M14 are used to ensure that the current direction output to the power battery is in a predetermined direction by controlling on and off.

[0055] The switch tubes M11, M12, M13, and M14 can also be replaced by diodes. Figure 2 In the embodiment, the structure of the first voltage converter 13 is utilized to perform reverse boosting from the power battery to the first voltage converter 13 .

[0056] Figure 2 The two AC charging circuits share a set of output ports of the on-board charger 20.

[0057] In another embodiment, the N AC charging loops include N AC-DC converters 12 corresponding to each AC charging loop one by one, and the N AC charging loops share the same first voltage converter 13 .

[0058] Figure 3 FIG. 1 is a schematic diagram of a power battery charging system provided by another exemplary embodiment. Figure 3As shown, three AC charging ports are connected to three AC-DC converters 12 one by one. Each AC-DC converter 12 is connected to the same first voltage converter 13. When there are multiple AC charging ports with plugs and multiple AC-DC converters 12 are working at the same time, the first voltage converter 13 simultaneously receives the voltages output by multiple AC-DC converters 12 and converts the received voltages. In this way, the device settings are reduced and the internal space of the vehicle is saved.

[0059] In addition to the AC charging circuit, the power battery charging system may also include M DC charging circuits, where M≥1. That is, the vehicle may be provided with both a DC charging circuit and an AC charging circuit.

[0060] In one embodiment, at least one DC charging circuit among the M DC charging circuits includes a DC charging port 21 and a second voltage converter 22 .

[0061] The DC charging port 21 is used to connect a DC charging gun; the second voltage converter 22 is connected to the DC charging gun and the power battery respectively, and is used to convert the DC power input into a voltage and input it into the power battery to charge the power battery.

[0062] Figure 4 FIG. 1 is a schematic diagram of a power battery charging system provided by another exemplary embodiment. Figure 4 As shown, the power battery charging system includes multiple DC charging circuits and multiple AC charging circuits. The multiple DC charging circuits include multiple second voltage converters 22.

[0063] In one embodiment, the second voltage converter 22 can reuse the bridge arm in the motor controller and the coil in the drive motor.

[0064] Figure 5 FIG. 1 is a schematic diagram of a power battery charging system provided by another exemplary embodiment. Figure 5 As shown, the AC charging gun 14 in the AC charging pile can be connected to the AC charging port 11. The DC charging gun 23 in the DC charging pile can be connected to the DC charging port 21. The power battery charging system includes three AC charging circuits and three DC charging circuits. The positive end of the power battery is provided with a main positive relay K1, a pre-charge relay K2, a pre-charge resistor R1 and a main negative relay K3.

[0065] The DC charging circuit also includes a DC charging positive contactor K4 / K6 / K8, a DC charging negative contactor K5 / K7 / K9, and a charging port step-down side capacitor (a second capacitor C2 / a fourth capacitor C4).

[0066] Among them, a DC charging circuit includes a first DC charging positive contactor K4, a first DC charging negative contactor K5, and a second capacitor C2. Among them, the second voltage converter 22 includes a motor coil, a three-phase bridge arm in a motor controller (including insulated gate bipolar transistors (IGBT) VT1, VT2, VT3, VT4, VT5, VT6), and a bus capacitor (first capacitor C1) of the motor controller.

[0067] In this DC charging circuit, the positive pole of the DC charging port 21 is connected to the center point of the coil in the motor through K4, the first bus terminal of the bridge arm in the motor controller is connected to the positive pole of the power battery, the second bus terminal of the bridge arm in the motor controller is connected to the negative pole of the power battery, and connected to the negative pole of the DC charging port through K5.

[0068] Another DC charging circuit includes a second DC charging positive contactor K6, a second DC charging negative contactor K7, and a fourth capacitor C4. Among them, the second voltage converter 22 includes a first bridge arm (including IGBT VT7, VT8), a fifth inductor L5, and a third capacitor C3. The positive electrode of the DC charging port 21 is connected to the midpoint of the first bridge arm through K6 and the fifth inductor L5, the first end of the first bridge arm is connected to the positive electrode of the power battery, the second end of the first bridge arm is connected to the negative electrode of the power battery, and is connected to the negative electrode of the DC charging port 21 through K7.

[0069] The third DC charging circuit includes a third DC charging positive contactor K8 and a third DC charging negative contactor K9.

[0070] In this embodiment, in one of the three DC charging circuits, the second voltage converter 22 reuses the bridge arm in the motor controller and the coil in the drive motor, saving the device settings; in one DC charging circuit, simple devices and structures are used for voltage conversion; in the third DC charging circuit, charging is performed directly without boosting the voltage.

[0071] Figure 6 and Figure 7 yes Figure 5 Schematic diagram of current flow during charging in one DC charging circuit. Figure 5 In the embodiment, the boost charging is divided into two stages by using a DC charging circuit that reuses the motor controller and the drive motor:

[0072] (1) The motor controller controls the lower bridge arms VT2, VT4, and VT6 to charge the motor coil. The motor coil acts as an inductor, and the current flows as follows: Figure 6The current flows from the positive pole of the DC charging port to the DC charging positive pole contactor K4, passes through the motor coil and the lower bridge arm VT6, VT4, and VT2 of the motor controller, and then returns to the negative pole of the DC charging port through the DC charging negative pole contactor K5.

[0073] (2) The motor controller controls the upper bridge arms VT5, VT3, and VT1 to turn on and turns off the lower bridge arms VT6, VT4, and VT2. The direction of the current in the motor coil does not change. After releasing energy and superimposing it with the current output by the DC charging port, it flows to the power battery through the upper bridge arms VT5, VT3, and VT1 of the motor controller to charge the power battery. The current flows as follows: Figure 7 shown.

[0074] Figure 8 yes Figure 5 Schematic diagram of current flow when one DC charging circuit and one AC charging circuit are charged simultaneously in an embodiment of the present invention, the current flow is as follows Figure 8 As indicated by the arrow in .

[0075] Fig. 9 yes Figure 5 Schematic diagram of current flow when one DC charging circuit and three AC charging circuits are charged simultaneously in an embodiment of the present invention, the current flow is as follows Fig. 9 As indicated by the arrow in .

[0076] Fig.10 yes Figure 5 Schematic diagram of current flow when three DC charging circuits and three AC charging circuits are charged simultaneously in the embodiment of the present invention, the current flow is as follows Fig.10 As indicated by the arrow in .

[0077] In another embodiment, two of the M DC charging circuits can reuse two drive systems in the vehicle, each drive system including a motor controller and a drive motor. In this embodiment, the vehicle can be a dual-motor driven vehicle.

[0078] Fig.11 FIG. 1 is a schematic diagram of a power battery charging system provided by another exemplary embodiment. Fig.11 As shown, the second voltage converters 22 in the two DC charging circuits each reuse a set of motor controllers and motor coils in the vehicle. The second voltage converters 22 in the two DC charging circuits have similar circuit structures. In this embodiment, for a dual-motor driven vehicle, the reuse level is higher.

[0079] Fig.12 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment. Fig.12 and Figure 5 The difference is that Fig.12Each AC charging circuit has a dedicated first voltage converter 13, that is, the first voltage converter 13 of each AC charging circuit is not shared.

[0080] Fig.13 It is a structural schematic diagram of a power battery charging system provided by yet another exemplary embodiment. Fig.13 and Fig.12 The difference is that Fig.12 The three first voltage converters 13 share the output end of the on-board charger. The on-board charger has only one output end. Fig.13 The three first voltage converters 13 do not share the output end of the on-board charger. The output end of the on-board charger corresponds to the three AC charging circuits and has three output ends.

[0081] The present disclosure also provides a vehicle, including a power battery and the power battery charging system provided by the present disclosure.

[0082] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0083] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0084] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A power battery charging system, characterized in that: The power battery charging system includes N AC charging circuits, N≥2, and each AC charging circuit includes: AC charging port (11), used for connecting an AC charging gun; an AC-DC converter (12), connected to the AC charging port, and used for converting the AC power inputted from the AC charging port into DC power; A first voltage converter (13) is connected to the AC-DC converter and the power battery respectively, and is used to convert the direct current output by the AC-DC converter into a voltage and input it into the power battery (10) to charge the power battery; The AC-DC converters and the first voltage converter in the N AC charging circuits are integrated in the same on-board charger (20).

2. The power battery charging system according to claim 1, characterized in that: The N AC charging loops include N AC-DC converters corresponding to each AC charging loop one by one, and the N AC charging loops share the same first voltage converter.

3. The power battery charging system according to claim 1, characterized in that: The AC-DC converter is a PFC, and the first voltage converter is an LLC or CLLC resonant converter.

4. The power battery charging system according to claim 3, characterized in that: The AC-DC converter comprises a first inductor (L1), a second inductor (L2), a first group of switch tubes, a second group of switch tubes and a third group of switch tubes, each group of switch tubes comprising two switch tubes connected in series; The positive input end of the AC-DC converter is divided into a first branch and a second branch, the first branch is connected to the middle node of the first group of switch tubes through the first inductor, the second branch is connected to the middle node of the second group of switch tubes through the second inductor, the negative input end of the AC-DC converter is connected to the middle node of the third group of switch tubes, the first end of each group of switch tubes is connected in common and serves as the first output end of the AC-DC converter, and the second end of each group of switch tubes is connected in common and serves as the second output end of the AC-DC converter.

5. The power battery charging system according to claim 3, characterized in that: The first voltage converter includes a transformer, a third inductor (L3), a fourth inductor (L4), a fifth capacitor (C5), a sixth capacitor (C6), a fourth group of switch tubes, a fifth group of switch tubes, a sixth group of switch tubes and a seventh group of switch tubes, each group of switch tubes includes two switch tubes connected in series; The first end of the first side of the transformer is connected to the middle node of the fourth group of switch tubes through the third inductor and the fifth capacitor in sequence, the second end of the first side of the transformer is connected to the middle node of the fifth group of switch tubes, the first end of the second side of the transformer is connected to the middle node of the sixth group of switch tubes, and the second end of the second side of the transformer is connected to the middle node of the seventh group of switch tubes through the fourth inductor and the sixth capacitor in sequence; The first end of the fourth group of switch tubes and the first end of the fifth group of switch tubes are connected together and serve as the positive input end of the first voltage converter, and the second end of the fourth group of switch tubes and the second end of the fifth group of switch tubes are connected together and serve as the negative input end of the first voltage converter; The first end of the sixth group of switch tubes and the first end of the seventh group of switch tubes are connected together and serve as the positive output end of the first voltage converter. The second end of the sixth group of switch tubes and the second end of the seventh group of switch tubes are connected together and serve as the negative output end of the first voltage converter.

6. The power battery charging system according to claim 1, characterized in that: The power battery charging system also includes M DC charging circuits, where M≥1.

7. The power battery charging system according to claim 6, characterized in that: At least one DC charging circuit among the M DC charging circuits comprises: A DC charging port (21), used for connecting a DC charging gun; The second voltage converter (22) is connected to the DC charging gun and the power battery respectively, and is used for converting the DC power input from the DC charging port into a voltage and then inputting the voltage into the power battery to charge the power battery.

8. The power battery charging system according to claim 7, characterized in that: The second voltage converter multiplexes the bridge arm in the motor controller and the coil in the drive motor.

9. The power battery charging system according to claim 8, characterized in that: Two of the M DC charging circuits reuse two drive systems in the vehicle, and each drive system includes a motor controller and a drive motor.

10. The power battery charging system according to claim 8, characterized in that: The positive pole of the DC charging port is connected to the center point of the coil in the motor, the first bus terminal of the bridge arm in the motor controller is connected to the positive pole of the power battery, and the second bus terminal of the bridge arm in the motor controller is respectively connected to the negative pole of the power battery and the negative pole of the DC charging port.

11. The power battery charging system according to claim 7, characterized in that: The second voltage converter includes a first bridge arm and a fifth inductor, the positive pole of the DC charging port is connected to the midpoint of the first bridge arm through the fifth inductor, the first end of the first bridge arm is connected to the positive pole of the power battery, and the second end of the first bridge arm is respectively connected to the negative pole of the power battery and the negative pole of the DC charging port.

12. A vehicle, characterized in that: The invention comprises a power battery and a power battery charging system according to any one of claims 1 to 11.

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