Charging and discharging circuit and electric vehicle

Abstract

The utility model discloses a charging and discharging circuit and an electric automobile. The charging and discharging circuit comprises a first contact, a second contact, a first main positive relay, a first battery pack, a first main negative relay, a second main positive relay, a second battery pack, a second main negative relay and an intermediate relay, and the first main positive relay, the first battery pack, the first main negative relay and the second contact are sequentially connected in series from the first contact. An independent main loop of the first battery pack is formed; starting from the first contact, a first main positive relay, a first battery pack, an intermediate relay, a second battery pack and a second main negative relay are sequentially connected in series to form a series main loop of the first battery pack and the second battery pack; and starting from the first contact, a second main positive relay, a second battery pack, a second main negative relay and a second contact are sequentially connected in series to form an independent main loop of the second battery pack. According to the utility model, the technical problem of high use cost of the high-voltage charging technology is solved.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, in particular to a charging and discharging circuit and an electric vehicle. Background Art

[0002] In related technologies, when charging with rechargeable batteries, the most common charging voltage is relatively low. For example, the current mainstream is 380V three-phase electric vehicle charging piles, also known as DC fast charging. However, in actual needs, a higher charging voltage may be required for charging. However, when charging with a higher charging voltage, it is often necessary to design a higher-cost charging circuit to meet the development trend of new energy.

[0003] Therefore, in the related art, there is a problem that the use of high-voltage charging technology has high costs.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Utility Model Content

[0005] The embodiments of the utility model provide a charging and discharging circuit and an electric vehicle, so as to at least solve the technical problem of high cost of using high-voltage charging technology.

[0006] To achieve the above-mentioned objectives, the utility model provides a charging and discharging circuit, comprising: a first contact, a second contact, a first main positive relay, a first battery pack, a first main negative relay, a second main positive relay, a second battery pack, a second main negative relay and an intermediate relay, wherein, starting from the first contact, the first main positive relay, the first battery pack, the first main negative relay and the second contact are connected in series in sequence to form a separate main loop of the first battery pack; starting from the first contact, the first main positive relay, the first battery pack, the intermediate relay, the second battery pack, and the second main negative relay are connected in series in sequence to form a series main loop of the first battery pack and the second battery pack; starting from the first contact, the second main positive relay, the second battery pack, the second main negative relay and the second contact are connected in series in sequence to form a separate main loop of the second battery pack.

[0007] Optionally, the charge and discharge circuit further includes: a first pre-charge relay and a first pre-charge resistor, wherein the first pre-charge relay and the first pre-charge resistor are connected in series and then in parallel with the first main positive relay to form a first pre-charge loop.

[0008] Optionally, the charge and discharge circuit further includes: a second pre-charge relay and a second pre-charge resistor, wherein the second pre-charge relay and the second pre-charge resistor are connected in series and then in parallel with the second main positive relay to form a second pre-charge loop.

[0009] Optionally, a first current sensor is provided at the charge and discharge input terminal or the output terminal of the first battery pack.

[0010] Optionally, a second current sensor is provided at the charge and discharge input terminal or the output terminal of the second battery pack.

[0011] Optionally, a first fuse, wherein the first fuse is arranged at the wire connection of the first contact.

[0012] Optionally, a second fuse, wherein the second fuse is arranged at the wire connection of the first main negative relay.

[0013] Optionally, a third fuse, wherein the third fuse is arranged at the wire connection of the second main positive relay.

[0014] Optionally, a first voltage provided by the first battery pack is the same as or different from a second voltage provided by the second battery pack.

[0015] Optionally, the first voltage provided by the first battery pack is the same as the second voltage provided by the second battery pack, both of which are 400V.

[0016] According to another aspect of the embodiment of the utility model, an electric vehicle is also provided, comprising the charging and discharging circuit described in any one of the above items.

[0017] In an embodiment of the utility model, through the first contact, the second contact, the first main positive relay, the first battery pack, the first main negative relay, the second main positive relay, the second battery pack, the second main negative relay and the intermediate relay, wherein, starting from the first contact, the first main positive relay, the first battery pack, the first main negative relay and the second contact are connected in series in sequence to form a separate main circuit of the first battery pack; starting from the first contact, the first main positive relay, the first battery pack, the intermediate relay, the second battery pack, and the second main negative relay are connected in series in sequence to form a series main circuit of the first battery pack and the second battery pack; starting from the first contact, the second main positive relay, the second battery pack, the second main negative relay and the second contact are connected in series in sequence to form a separate main circuit of the second battery pack, thereby achieving the technical effect of voltage switching between the first battery pack and the second battery pack, thereby solving the technical problem of high cost of using high-voltage charging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0019] Figure 1 It is a flow chart of a charging and discharging circuit provided according to an embodiment of the utility model;

[0020] Figure 2It is a schematic diagram of an optional 800V / 400V compatible switching circuit system provided according to an embodiment of the utility model.

[0021] The above drawings include the following reference numerals:

[0022] The first main positive relay 1, the first main negative relay 2, the second main positive relay 3, the second main negative relay 4, the intermediate relay 5, the first battery pack 6, the second battery pack 7, the first contact 8, the second contact 9, the first pre-charging resistor 10, the second pre-charging resistor 11, the first pre-charging relay 12, the second pre-charging relay 13, the first fuse 14, the second fuse 15, the third fuse 16, the first current sensor 17, and the second current sensor 18. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present utility model will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0026] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0027] In order to solve the problems of high cost, low coverage and difficult charging due to high voltage charging technology, the utility model provides a charging and discharging circuit. Figure 1 is a schematic diagram of a charging and discharging circuit provided according to an embodiment of the utility model, such as Figure 1As shown, the charge and discharge circuit includes: a first contact 8, a second contact 9, a first main positive relay 1, a first battery pack 6, a first main negative relay 2, a second main positive relay 3, a second battery pack 7, a second main negative relay 4 and an intermediate relay 5, wherein, starting from the first contact 8, the first main positive relay 1, the first battery pack 6, the first main negative relay 2 and the second contact 9 are connected in series in sequence to form a separate main loop of the first battery pack 7; starting from the first contact 8, the first main positive relay 1, the first battery pack 6, the intermediate relay 5, the second battery pack 7, and the second main negative relay 4 are connected in series in sequence to form a series main loop of the first battery pack 6 and the second battery pack 7; starting from the first contact 8, the second main positive relay 3, the second battery pack 7, the second main negative relay 4 and the second contact 9 are connected in series in sequence to form a separate main loop of the second battery pack 7.

[0028] Through the above circuit structure, the charge and discharge circuit includes a separate main circuit of the first battery pack formed by connecting the first main positive relay, the first battery pack, the first main negative relay and the second contact in series from the first contact; a separate main circuit of the second battery pack formed by connecting the second main positive relay, the second battery pack, the second main negative relay and the second contact in series from the first contact; and a series main circuit of the first battery pack and the second battery pack formed by connecting the first main positive relay, the first battery pack, the intermediate relay, the second battery pack and the second main negative relay in series from the first contact. That is, the above circuit structure effectively realizes the charge and discharge circuit that uses the first battery pack and the second battery pack separately for charge and discharge, and connects the first battery pack and the second battery pack in series to form a series main circuit including the first battery pack and the second battery pack, and can charge and discharge based on the series main circuit. That is, the low-voltage charge and discharge function of the individual battery packs is effectively realized, and the high-voltage charge and discharge function after the battery packs are connected in series can also be realized. In addition, flexible conversion can be made between charging and discharging of a single battery pack and charging and discharging of battery packs in series based on the switching between the above-mentioned intermediate relays, which effectively improves the flexibility of charging and discharging and effectively solves the technical problem of high cost of using high-voltage charging technology in related technologies.

[0029] As an optional embodiment, the charge and discharge circuit has three states. State 1 is connected in series from the first contact 8 to the first main positive relay 1, the first battery pack 6, the first main negative relay 2 and the second contact 9 to form a separate main circuit of the first battery pack 7; State 2 is connected in series from the first contact 8 to the first main positive relay 1, the first battery pack 6, the intermediate relay 5, the second battery pack 7, the second main negative relay 4 to form a series main circuit of the first battery pack 6 and the second battery pack 7; State 3 is connected in series from the first contact 8 to the second main positive relay 3, the second battery pack 7, the second main negative relay 4 and the second contact 9 to form a separate main circuit of the second battery pack 7. Among them, the first battery pack and the second battery pack in state 2 are connected in series, which will provide a larger voltage. The voltages provided by state 1 and state 3 are less than the voltage provided by state 2. By converting the three states in the charge and discharge circuit, the conversion of the charge and discharge voltage can be achieved.

[0030] As an optional embodiment, in order to protect the battery pack charging process, a pre-charging circuit may also be included in the above-mentioned charging and discharging circuit. For example, the pre-charging circuit may be formed by the following design: a first pre-charging relay and a first pre-charging resistor, wherein the first pre-charging relay and the first pre-charging resistor are connected in series and then in parallel with the first main positive relay 1 to form a first pre-charging circuit.

[0031] In the above optional embodiment, the first pre-charge circuit can be used to protect the charging of the first battery pack 6. When the charge and discharge circuit is in state one, the first main positive relay 1 is first opened, the first pre-charge relay is closed, and the first main negative relay 2 is closed. The current flows through the first pre-charge resistor and flows into the first battery pack 6. Because the current flows through the first pre-charge resistor, the current reaching the first battery pack 6 will not be too large, so the first battery pack 6 will not be damaged. After the current stabilizes, the first main positive relay 1 is closed at this time, and the current will not flow into the first pre-charge resistor. The current will flow directly into the first battery pack 6, and the current will gradually increase. If there is no pre-charge circuit in the charge and discharge circuit, the current will flow directly into the first battery pack 6. If the current is very large at this time, the first battery pack 6 will be damaged. When the charge and discharge circuit is in the state of discharge, first open the first main positive relay 1, close the first pre-charge relay, close the first main negative relay 2, and when the first battery pack 6 is charging the electric vehicle, because of the first pre-charge resistor, the current when charging the electric vehicle will not be very large, so the electric vehicle will not be damaged. After the current stabilizes, close the first main positive relay 1, the current will not flow into the first pre-charge resistor, but will directly flow into the electric vehicle, making the current gradually increase, and then charge the electric vehicle. Through the above structure, the first pre-charge circuit realizes the protection of the charging process of the first battery pack 6, and the protection of the electric vehicle when the first battery pack 6 is discharged.

[0032] As an optional embodiment, in order to protect the battery pack charging process, a pre-charging circuit may also be included in the above-mentioned charging and discharging circuit. For example, the pre-charging circuit may be formed by the following design: a second pre-charging relay and a second pre-charging resistor, wherein the second pre-charging relay and the second pre-charging resistor are connected in series and then in parallel with the second main positive relay 3 to form a second pre-charging circuit.

[0033] In the above optional embodiment, the second pre-charge circuit can be used to protect the charging of the second battery pack 7. When the charge and discharge circuit is in the charging state three, first open the second main positive relay 3, close the second pre-charge relay, close the second main negative relay 4, and the current flows into the second battery pack 7 through the second pre-charge resistor. Because the current flows through the second pre-charge resistor, the current reaching the second battery pack 7 will not be too large to damage the second battery pack 7. After the current stabilizes, at this time, close the second main positive relay 3, the current will not flow into the second pre-charge resistor, and the current will flow directly into the second battery pack 7, and the current will gradually increase. If there is no pre-charge circuit in the charge and discharge circuit, the current will flow directly into the second battery pack 7. If the current is very large at this time, the second battery pack 7 will be damaged. When the charge and discharge circuit is in the discharge state of state three, first open the second main positive relay 3, close the second pre-charge relay, close the second main negative relay 4, and when the second battery pack 7 is charging the electric vehicle, because of the second pre-charge resistor, the current when charging the electric vehicle will not be very large, so as to damage the electric vehicle. After the current stabilizes, at this time, close the second main positive relay 3, the current will not flow into the second pre-charge resistor, but will directly flow into the electric vehicle, making the current gradually increase, and then charge the electric vehicle. Through the above structure, the pre-charge circuit realizes the protection of the charging process of the second battery pack 7, and the protection of the electric vehicle when the second battery pack 7 is discharged.

[0034] As an optional embodiment, a first current sensor is provided at the charge and discharge input end or output end of the first battery pack 6 .

[0035] In the above optional embodiment, the first current sensor measures the magnitude of the current flowing through the first battery pack 6. The corresponding current can be known in time through the current sensor. For example, when the circuit is in the working state of the separate main circuit of the first battery pack 6, the magnitude of the current of the separate main circuit of the first battery pack 6 is obtained, and the charge and discharge control of the first battery pack 6 is determined according to the obtained current magnitude. For example, the end time of charge and discharge is determined according to the magnitude of the current, etc. For another example, when the circuit is in the working state of the series main circuit of the first battery pack 6 and the second battery pack 7, the magnitude of the current on the series main circuit is obtained, and the charge and discharge control on the series main circuit is determined according to the obtained current magnitude.

[0036] As an optional embodiment, a second current sensor is provided at the charge and discharge input terminal or the output terminal of the second battery pack 7 .

[0037] In the above optional embodiment, the second current sensor measures the current flowing through the second battery pack 7. The corresponding current can be known in time through the current sensor. For example, when the circuit is in the working state of the separate main circuit of the second battery pack 7, the current of the separate main circuit of the second battery pack 7 is obtained, and the charge and discharge control of the second battery pack 7 is determined according to the obtained current. For example, the end time of charging and discharging is determined according to the current. For another example, when the circuit is in the working state of the series main circuit of the first battery pack 6 and the second battery pack 7, the current on the series main circuit is obtained, and the charge and discharge control on the series main circuit is determined according to the obtained current. It should be noted that when the circuit is in the working state of the series main circuit of the first battery pack 6 and the second battery pack 7, the first current sensor and the second current sensor can back up each other to achieve effective monitoring of the current on the entire series main circuit. As an optional embodiment, in order to realize the protection of the charging and discharging circuit, the above charging and discharging circuit may also include: a first fuse, wherein the first fuse is arranged at the wire connection of the first contact 8.

[0038] In the above optional embodiment, the first fuse can be used to protect the entire charging and discharging circuit. In the charging and discharging circuit containing the first fuse, when the current flowing through the first fuse exceeds the rated current of the first fuse, the first fuse will automatically cut off the circuit to prevent the circuit from overloading, and prevent the wires, sockets and electrical equipment from overheating, burning or causing a fire. When a short circuit occurs in the charging and discharging circuit containing the first fuse, the first fuse will quickly cut off the circuit to prevent excessive current from causing a fire or damaging electrical equipment. The first fuse protects the entire charging and discharging circuit to prevent excessive current from damaging electrical components. When the current in the entire charging and discharging circuit is large, the first fuse will immediately blow the circuit, thereby protecting the entire charging and discharging circuit.

[0039] For example, when the charge and discharge circuit is in state two, the first fuse is used to protect the first battery pack 6, the second battery pack 7 and the devices on the entire series main circuit. When the charge and discharge circuit is in the charging state two, if the current during charging is too large, it will cause damage to the first battery pack 6 and the second battery pack 7. The first fuse is added to the charge and discharge circuit in state two. When the current during charging is too large, the first fuse will quickly cut off the circuit to prevent the current from being too large and causing damage to the first battery pack 6 and the second battery pack 7. When the charge and discharge circuit is in the discharging state two, if the current during discharging is too large, it will cause damage to the electric vehicle. The first fuse is added to the charge and discharge circuit in state two. When the current during discharging is too large, the first fuse will quickly cut off the circuit to prevent the current from being too large and causing damage to the electric vehicle.

[0040] As an optional embodiment, in order to protect the charging and discharging circuit, the above-mentioned charging and discharging circuit may further include: a second fuse, wherein the second fuse is arranged at the wire connection of the first main negative relay 2.

[0041] In the above optional embodiment, the second fuse can be used to protect the devices on the separate main circuit including the first battery pack 6. When the charging and discharging circuit is in the charging state of state one, if the current during charging is too large, it will cause damage to the first battery pack 6. A second fuse is added to the charging and discharging circuit in state one. When the current during charging is too large, the second fuse will quickly cut off the circuit to prevent the current from being too large and causing damage to the first battery pack 6. When the charging and discharging circuit is in the discharging state of state one, if the current during discharging is too large, it will cause damage to the electric vehicle. A second fuse is added to the charging and discharging circuit in state one. When the current during discharging is too large, the second fuse will quickly cut off the circuit to prevent the current from being too large and causing damage to the electric vehicle.

[0042] As an optional embodiment, in order to protect the charging and discharging circuit, the above-mentioned charging and discharging circuit may further include: a third fuse, wherein the third fuse is arranged at the wire connection of the second main positive relay.

[0043] In the above optional embodiment, the third fuse can be used to protect the devices on the separate main circuit including the second battery pack 7. When the charging and discharging circuit is in the charging state of state three, if the current during charging is too large, it will cause damage to the second battery pack 7. A third fuse is added to the charging and discharging circuit in state three. When the current during charging is too large, the third fuse will quickly cut off the circuit to prevent the excessive current from damaging the second battery pack 7. When the charging and discharging circuit is in the discharging state of state three, if the current during discharging is too large, it will cause damage to the electric vehicle. A third fuse is added to the charging and discharging circuit in state three. When the current during discharging is too large, the third fuse will quickly cut off the circuit to prevent the excessive current from damaging the electric vehicle.

[0044] As an optional embodiment, the first voltage provided by the first battery pack 6 is the same as or different from the second voltage provided by the second battery pack 7 .

[0045] In the above optional embodiment, when the first battery pack 6 and the second battery pack 7 are connected in series, a larger voltage is provided, and the larger voltage value is the result of adding the first voltage provided by the first battery pack 6 and the second voltage provided by the second battery pack 7. The first battery pack 6 and the second battery pack 7 can discharge the electric vehicle through the above circuit, and other power supply equipment can charge the first battery pack 6 and the second battery pack 7 through the above circuit.

[0046] As an optional embodiment, the first voltage provided by the first battery pack 6 and the second voltage provided by the second battery pack 7 are the same, both of which are 400V.

[0047] In the above optional embodiment, when the first battery pack 6 is connected in series with the second battery pack 7, a voltage of 800V can be provided. In the case of state two, the first battery pack 6 is connected in series with the second battery pack 7, and a voltage of 800V can be provided; in the case of state one, the first battery pack 6 can provide a voltage of 400V; in the case of state three, the second battery pack 7 can provide a voltage of 400V. By converting the above states, it is possible to charge the electric vehicle at 400V and at 800V. It should be noted that providing the above voltages of 400V and 800V is only an example. In specific implementation, other voltage values ​​can also be superimposed, and examples are not given one by one here.

[0048] In the relevant technology, 400V electric vehicles use a more common voltage platform, which is not much different from 800V electric vehicles in terms of vehicle system architecture and high-voltage electrical system topology. When charging a 400V electric vehicle, if the previous 400V DC fast charging pile can be used, there is no need for an additional DC / DC converter (DC / DC converter: DC / DC converter) to boost the voltage, which can reduce costs. Compared with 400V electric vehicles, 800V electric vehicles have obvious advantages in charging speed, energy consumption, cruising range, charging efficiency, etc., and are more in line with the development trend of new energy vehicles. However, the current mainstream is 380V three-phase electric vehicle charging piles, also known as DC fast charging. This type of charging pile has a large power, the output current is DC, and the voltage range is between 200-700V, which is not applicable to the charging requirements of electric vehicles with an 800V voltage level.

[0049] To solve the above problems, in an optional implementation of the utility model, an 800V / 400V compatible switching circuit system is provided. Figure 2 is a schematic diagram of an optional 800V / 400V compatible switching circuit system provided according to an embodiment of the utility model, such as Figure 2 As shown, the 800V / 400V compatible switching circuit system includes: 4 main relays, 2 pre-charge relays, 2 pre-charge resistors, 3 fuses, 2 current sensors, and 1 Relay (Breaktor).

[0050] The working modes of the 800V / 400V compatible switching circuit system include:

[0051] Mode 1: The main positive relay 1 (first main positive relay 1), the pre-charging relay 1 (first pre-charging relay 12) and the pre-charging resistor 1 (first pre-charging resistor 10) form a pre-charging circuit 1, and together with the battery pack B1 (first battery pack 6), the current sensor 1 (first current sensor 17), the FUSE1 (first fuse 14), the FUSE2 (second fuse 15), and the main negative relay 1 (first main negative relay 2), form a separate main circuit of the B1 battery pack (first battery pack 6).

[0052] In the above-mentioned mode 1, the pre-charge relay 1 protects the battery pack B1. When mode 1 is in the charging state, it prevents the current flowing into the battery pack B1 from being too large and burning the battery pack B1; when mode 1 is in the discharging state, it prevents the current flowing into the electric vehicle from being too large and burning the electric vehicle. When mode 1 is in the process of charging and discharging, the pre-charge relay 1 is closed first, and the main positive relay 1 is opened. After the current is stable, the pre-charge relay 1 is opened, and the main positive relay 1 is closed to gradually increase the current, and the current is stable. FUSE2 protects the battery pack B1. When mode 1 is in the charging state, it prevents the current flowing into the battery pack B1 from being too large and burning the battery pack B1. In the case of excessive current, FUSE2 will immediately cut off the circuit to protect the battery pack B1. When mode 1 is in the discharging state, it prevents the current flowing into the electric vehicle from being too large and burning the electric vehicle. In the case of excessive current, FUSE2 will immediately cut off the circuit to protect the electric vehicle.

[0053] Mode 2: The main positive relay 1 (first main positive relay 1), the pre-charging relay 1 (first pre-charging relay 12) and the pre-charging resistor 1 (first pre-charging resistor 10) form a pre-charging circuit 1, and the battery pack B1 (first battery pack 6), current sensor 1 (first current sensor 17), Relay (breaktor) (intermediate relay 5), battery pack B2 (second battery pack 7), current sensor 2 (second current sensor 18), main negative relay 2 (second main negative relay 4) and FUSE1 (first fuse 14) form a B1+B2 battery pack (first battery pack 6+second battery pack 7) series main circuit.

[0054] In the above-mentioned mode 2, battery pack B1 and battery pack B2 are connected in series, and the power supply voltage provided is the sum of the first voltage provided by battery pack B1 and the second voltage provided by battery pack B2. Current sensor 1 measures the current flowing through battery pack B1, and current sensor 2 measures the current flowing through battery pack B2. FUSE1 protects battery pack B1 and battery pack B2. When mode 2 is in charging, it prevents excessive current from flowing into battery pack B1 and battery pack B2, which may burn battery pack B1 and battery pack B2. In the case of excessive current, FUSE1 will immediately cut off the circuit to protect battery pack B1 and battery pack B2. When mode 2 is in discharging, it prevents excessive current from flowing into the electric vehicle, which may burn the electric vehicle. In the case of excessive current, FUSE1 will immediately cut off the circuit to protect the electric vehicle.

[0055] Mode three: the main positive relay 2 (the second main positive relay 3), the pre-charging relay 2 (the second pre-charging relay 13) and the pre-charging resistor 2 (the second pre-charging resistor 11) form a pre-charging circuit 2, and together with FUSE3 (the third fuse 16), the battery pack B2 (the second battery pack 7), the current sensor 2 (the second current sensor 18), FUSE1 (the first fuse 14), and the main negative relay 2 (the second main negative relay 4), form a separate main circuit of the B2 battery pack (the second battery pack 7).

[0056] In the above-mentioned mode three, the pre-charge relay 2 protects the battery pack B2. When mode three is in the charging state, it prevents the current flowing into the battery pack B2 from being too large and burning the battery pack B2; when mode three is in the discharging state, it prevents the current flowing into the electric vehicle from being too large and burning the electric vehicle. When mode three is in the process of charging and discharging, the pre-charge relay 2 is closed first, and the main positive relay 2 is opened. After the current is stable, the pre-charge relay 2 is opened, and the main positive relay 2 is closed to gradually increase the current, and the current is stable. FUSE3 protects the battery pack B2. When mode three is in the charging state, it prevents the current flowing into the battery pack B2 from being too large and burning the battery pack B2. In the case of excessive current, FUSE3 will immediately cut off the circuit to protect the battery pack B2. When mode three is in the discharging state, it prevents the current flowing into the electric vehicle from being too large and burning the electric vehicle. In the case of excessive current, FUSE3 will immediately cut off the circuit to protect the electric vehicle.

[0057] The above three modes can enable the charging and discharging circuit to switch the voltage between 400V and 800V at any time by adjusting the connection between the first battery pack 6 and the second battery pack 7, that is, it has the advantages of the 800V battery system in terms of charging speed, energy consumption, cruising range, charging efficiency and safety, and solves the problems of 800V super charging piles and high-voltage charging technology in the market, such as high cost, low coverage and difficult charging, so that it can be charged as conveniently and quickly as the 400V battery system.

[0058] The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0059] Obviously, the embodiments described above are only some embodiments of the utility model, not all embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0060] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0061] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0062] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0063] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A charging and discharging circuit, characterized in that: include: A first contact, a second contact, a first main positive relay, a first battery pack, a first main negative relay, a second main positive relay, a second battery pack, a second main negative relay and an intermediate relay, wherein, Starting from the first contact, the first main positive relay, the first battery pack, the first main negative relay and the second contact are connected in series in sequence to form a separate main circuit for the first battery pack; Starting from the first contact point, the first main positive relay, the first battery pack, the intermediate relay, the second battery pack, and the second main negative relay are connected in series in sequence to form a series main loop of the first battery pack and the second battery pack; Starting from the first contact, the second main positive relay, the second battery pack, the second main negative relay and the second contact are connected in series in sequence to form a separate main circuit of the second battery pack.

2. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A first pre-charging relay and a first pre-charging resistor, wherein: The first pre-charging relay and the first pre-charging resistor are connected in series and then in parallel with the first main positive relay to form a first pre-charging circuit.

3. The charge and discharge circuit according to claim 1, characterized in that: Also includes: The second pre-charge relay and the second pre-charge resistor, wherein, The second pre-charging relay and the second pre-charging resistor are connected in series and then in parallel with the second main positive relay to form a second pre-charging circuit.

4. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A first current sensor is provided at the charge and discharge input end or the output end of the first battery pack.

5. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A second current sensor is provided at the charge and discharge input terminal or the output terminal of the second battery pack.

6. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A first fuse, wherein the first fuse is arranged at a wire connection of the first contact.

7. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A second fuse, wherein the second fuse is arranged at a wire connection of the first main negative relay.

8. The charge and discharge circuit according to claim 1, characterized in that: Also includes: A third fuse, wherein the third fuse is arranged at a wire connection of the second main positive relay.

9. The charge and discharge circuit according to any one of claims 1 to 8, characterized in that: The first voltage provided by the first battery pack is the same as the second voltage provided by the second battery pack, both of which are 400V.

10. An electric vehicle, characterized in that: A charging and discharging circuit comprising the charging and discharging circuit according to any one of claims 1 to 9.

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