Charging and discharging circuit, battery pack and vehicle

Abstract

The embodiment of the application discloses a charging and discharging circuit, a battery pack and a vehicle, relates to the technical field of charging and discharging circuits, and the charging and discharging circuit comprises a main positive switch, a fast charging positive switch, a main negative switch, a fast charging negative switch, a pre-charging and pre-discharging switch, a current-limiting resistor and a switching switch. The first end of the main positive switch is used for connecting the positive electrode of a battery cell assembly. The first end of the fast charging positive switch is electrically connected with the second end of the main positive switch, and the second end is used for connecting the positive electrode of a charging pile. The first end of the main negative switch is used for connecting the negative electrode of the battery cell assembly. The first end of the fast charging negative switch is electrically connected with the second end of the main negative switch, and the second end is used for connecting the negative electrode of the charging pile. The first end of the pre-charging and pre-discharging switch is electrically connected with the main positive switch. The first end of the current-limiting resistor is electrically connected with the second end of the pre-charging and pre-discharging switch. The first end of the switching switch is electrically connected with the second end of the main positive switch, and the second end is electrically connected with the second end of the current-limiting resistor and the second end of the fast charging positive switch.

Description

Technical Field

[0001] This application relates to the field of charging and discharging circuit technology, and in particular to a charging and discharging circuit, a battery pack, and a vehicle. Background Technology

[0002] Electric vehicles are powered by high-voltage batteries, which transmit DC power to various electrical devices in the vehicle via a high-voltage direct current bus (HV). While some electric vehicles have reached 800V, a large number of 400V DC charging stations still exist on the market. Therefore, 800V electric vehicles require a boost module to convert the 400V DC charging station voltage to 800V.

[0003] However, there are capacitors on the positive and negative busbars inside the boost module. When using the boost module, the capacitors inside the boost module need to be charged first. When the fast charging contactor is closed, the current passing through the fast charging contactor is large because the capacitor is equivalent to a short circuit, and the fast charging contactor is prone to sticking. Utility Model Content

[0004] This application provides a charging and discharging circuit, a battery pack, and a vehicle, which can improve the technical problem of fast charging contactors being prone to sticking.

[0005] In a first aspect, embodiments of this application provide a charging and discharging circuit, which includes a main positive switch, a fast charging positive switch, a main negative switch, a fast charging negative switch, a pre-charge / pre-discharge switch, a current-limiting resistor, and a switching switch. The first terminal of the main positive switch is connected to the positive terminal of the battery cell assembly; the first terminal of the fast charging positive switch is electrically connected to the second terminal of the main positive switch, and the second terminal of the fast charging positive switch is connected to the positive terminal of the charging pile; the first terminal of the main negative switch is connected to the negative terminal of the battery cell assembly; the first terminal of the fast charging negative switch is electrically connected to the second terminal of the main negative switch, and the second terminal of the fast charging negative switch is connected to the negative terminal of the charging pile; the first terminal of the pre-charge / pre-discharge switch is electrically connected to the main positive switch; the first terminal of the current-limiting resistor is electrically connected to the second terminal of the pre-charge / pre-discharge switch; the first terminal of the switching switch is electrically connected to the second terminal of the main positive switch, and the second terminal of the switching switch is electrically connected to both the second terminal of the current-limiting resistor and the second terminal of the fast charging positive switch.

[0006] In the above technical solution, the current-limiting resistor can limit the current and establish a high-resistance path between the battery cell assembly and the charging pile, limiting the initial discharge current. After the pre-charge and pre-discharge switch is closed, the charging and discharging circuit performs pre-charging, so that the voltage of the bus capacitor rises slowly. This can avoid the impact on the fast charging positive switch caused by directly closing the fast charging positive switch and protect the fast charging positive switch.

[0007] The current-limiting resistor can limit the current and establish a high-resistance path between the cell assembly and the load capacitor, limiting the initial discharge current. After the pre-charge and pre-discharge switch is closed, the charge and discharge circuit performs pre-discharge, so that the voltage of the load capacitor rises slowly. This can avoid the impact on the main positive switch caused by directly closing the main positive switch and protect the main positive switch.

[0008] In some exemplary embodiments, the charging and discharging circuit further includes a boost module, a first input terminal of which is connected to the positive terminal of the charging pile, a second input terminal of which is connected to the negative terminal of the charging pile, a first output terminal of which is connected to the second terminal of the fast charging positive switch, and a second output terminal of which is connected to the second terminal of the fast charging negative switch.

[0009] In the above technical solution, the boost module can actively increase the lower voltage (e.g., 400V) provided by the charging pile to the higher voltage (e.g., 800V) required to match the battery pack. In this way, an 800V battery pack can achieve efficient fast charging on a 400V charging pile, breaking down the voltage platform barrier, making the vehicle backward compatible with mainstream charging facilities, and expanding the range of available fast charging networks.

[0010] When the battery pack needs to discharge, the high voltage of the battery (e.g., 800V) needs to be reduced to the standard voltage of the load or the power grid. At this time, the boost module reverses its operation, becoming a buck module to achieve energy output.

[0011] In some exemplary embodiments, the charging and discharging circuit further includes a current sensor, the first end of which is electrically connected to the second end of the main negative switch, and the second end of which is electrically connected to the first end of the fast charging negative switch.

[0012] In the above technical solution, the current sensor can quickly send the signal to the battery management system (BMS), and the BMS will disconnect the main positive switch and the main negative switch within milliseconds to cut off the circuit and prevent fire or equipment damage.

[0013] Current sensors can also be used to calculate the charge of battery cells, reflecting the lifespan and degree of aging of the battery cells.

[0014] Based on the real-time current readings from the current sensor, the BMS can predict the battery's heat generation capacity. If the current is high, the BMS will proactively increase the cooling system's power to prevent the battery from overheating; otherwise, it will reduce the cooling power to save energy.

[0015] Current sensors can distinguish the direction of current flow. Current flowing out of the battery powers the vehicle or discharges externally. Current flowing into the battery comes from a charging station or energy recovery, allowing the BMS to determine the vehicle's operating mode. In some exemplary embodiments, the charging and discharging circuit further includes a first motor controller, a first terminal of which is electrically connected to a second terminal of the switching switch, and a second terminal of which is electrically connected to a second terminal of the main negative switch.

[0016] In the above technical solution, the first motor controller can convert the DC power provided by the battery cell assembly into the three-phase AC power required to drive the motor, and precisely control the frequency and amplitude of the AC power, thereby controlling the speed and torque of the motor and realizing the acceleration, deceleration and cruising of the vehicle.

[0017] The first motor controller can also rectify the three-phase AC power generated by the motor into DC power and recharge the battery pack. When the vehicle is coasting or braking, the wheels drag the motor to rotate, temporarily turning the motor into a generator.

[0018] Energy recovery can improve a vehicle's energy efficiency, extend its driving range, and reduce wear on mechanical brakes. When the vehicle needs external power, the first motor controller inverts the battery's DC power into AC power for output.

[0019] In some exemplary embodiments, the charging and discharging circuit further includes a second motor controller, the first terminal of which is electrically connected to the second terminal of the switching switch, and the second terminal of which is electrically connected to the second terminal of the main negative switch.

[0020] In the above technical solution, one of the second motor controllers and the first motor controller is used to control the front drive motor, while the other is used to control the rear drive motor. The two motors can work together, and their combined output power and torque are greater than that of a single motor. When overtaking at high speed or climbing hills, the dual motors can provide sufficient power reserves.

[0021] In some exemplary embodiments, the charging and discharging circuit further includes a conductive element, a first end of which is electrically connected to the second end of the precharge and pre-discharge switch, and a second end of which is electrically connected to the second end of the fast charge positive switch. The rated current of the conductive element is adapted to the rated current of the precharge and pre-discharge switch.

[0022] In the above technical solution, the rated current of the conductive component is matched with the rated current of the precharge and pre-discharge switch. The overcurrent of the precharge and pre-discharge switch is relatively small. Therefore, the conductive component can be selected with a wire with similar overcurrent capacity, that is, a relatively thin wire, in order to save costs, reduce weight, and reduce space occupation.

[0023] In some exemplary embodiments, the charging and discharging circuit has a discharging mode and a charging mode; When the charging and discharging circuit is in discharge mode, and the differential voltage between the second terminal of the main positive switch and the second terminal of the main negative switch is less than or equal to the first threshold, the main positive switch is closed and the pre-charge and pre-discharge switch is open. When the charging / discharging circuit is in charging mode, and the differential voltage between the second terminal of the fast charging positive switch and the second terminal of the main negative switch is less than or equal to a second threshold, the main positive switch closes and the pre-charge / pre-discharge switch opens. In the above technical solution, by setting a first threshold, the voltage of the load capacitor rises to near the voltage of the battery cell assembly. At this point, the voltage difference between the load capacitor and the battery cell assembly is very small. Since the potential difference between the two ends of the main positive switch (the voltage of the battery cell assembly and the voltage of the load capacitor) is very small, no large inrush current will be generated when the main positive switch is closed. Similarly, by setting a second threshold, the voltage of the bus capacitor rises to near the voltage of the battery cell assembly. Again, the voltage difference between the bus capacitor and the battery cell assembly is very small. Again, since the potential difference between the two ends of the fast charging positive switch (the voltage of the battery cell assembly and the voltage of the bus capacitor) is very small, no large inrush current will be generated when the fast charging positive switch is closed.

[0024] Secondly, embodiments of this application provide a battery pack, which includes a charging and discharging circuit and a cell assembly. The positive terminal of the cell assembly is electrically connected to the first terminal of the main positive switch, and the negative terminal of the cell assembly is electrically connected to the first terminal of the main negative switch.

[0025] In some exemplary embodiments, a control unit is also included. The control unit is electrically connected to the controlled terminal of the main positive switch, the controlled terminal of the fast charging positive switch, the controlled terminal of the main negative switch, the controlled terminal of the fast charging negative switch, the controlled terminal of the precharge and pre-discharge switch, and the controlled terminal of the switching switch. The control unit is capable of controlling the on / off state of the main positive switch, the fast charging positive switch, the main negative switch, the fast charging negative switch, the precharge and pre-discharge switch, and the switching switch.

[0026] In the above technical solution, the control unit controls each switch, thereby enabling the battery pack to automatically precharge and pre-discharge.

[0027] Thirdly, embodiments of this application provide a vehicle, which includes a battery pack. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1This is a block diagram of a battery pack in one embodiment of this application; Figure 2 This is a block diagram of a charging and discharging circuit in one embodiment of this application; Figure 3 This is a block diagram of a charging and discharging circuit in another embodiment of this application; Figure 4 This is a block diagram of the charging and discharging circuit in another embodiment of this application; Figure 5 This is a block diagram of the charging and discharging circuit in another embodiment of this application; Figure 6 This is a block diagram of a charging and discharging circuit in one embodiment of this application; Figure 7 This is a block diagram of a charging and discharging circuit in one embodiment of this application.

[0030] Explanation of reference numerals in the attached diagram: 100, charging / discharging circuit; 110, main positive switch; 120, fast charging positive switch; 130, main negative switch; 140, fast charging negative switch; 150, pre-charge / pre-discharge switch; 160, switching switch; 170, current limiting resistor; 181, boost module; 182, current sensor; 183, conductive component; 191, first motor controller; 192, second motor controller; 200, battery pack; 210, battery cell assembly. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0033] Furthermore, the use of terms such as "first," "second," etc., in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0036] Electric vehicles are increasingly favored by consumers due to their intelligence, low noise, and superior power performance, and are widely used in various fields to replace traditional fuel vehicles. Unlike fuel vehicles, electric vehicles are powered by battery cells, which transmit direct current to various electrical devices in the vehicle, such as motor drives, air conditioning, and positive temperature coefficient heaters, via a high-voltage DC bus.

[0037] The voltage level of new energy vehicles has reached 800V, but there are still 400V DC charging piles on the market. This means that new energy vehicles need to add a boost module to solve the problem of charging the 800V power battery with 400V DC charging piles. However, there are bus capacitors on the positive and negative bus inside the boost module. When using the boost module, an additional pre-charge circuit is needed to charge the capacitors inside the boost module. Otherwise, it will cause the contactors inside the power battery to stick together.

[0038] Therefore, embodiments of this application provide a charging and discharging circuit, a battery pack, and a vehicle. The charging and discharging circuit, through two pre-charge switches, can perform pre-charging during charging and pre-discharging during discharging, thereby protecting the main positive switch and the fast charging positive switch.

[0039] The charging and discharging circuit, battery pack, and vehicle provided in the embodiments of this application are described below with reference to the accompanying drawings.

[0040] This application provides a vehicle comprising a high-voltage electrical system and a low-voltage electrical system. The high-voltage electrical system includes a battery pack 200, which supplies power to high-power electrical equipment (such as motors, inverters, and other high-voltage components) in the vehicle to drive it and maintain normal operation. The low-voltage electrical system includes a low-voltage battery (e.g., a 12V battery) and a DC-DC converter (DCDC). The DC-DC converter converts the high-voltage electricity from the battery pack 200 to low-voltage electricity to meet the signal transmission / control requirements of the vehicle; further details are omitted here.

[0041] like Figure 1 and Figure 2 As shown, the battery pack 200 includes a charging and discharging circuit 100 and a cell assembly 210. The charging and discharging circuit 100 is electrically connected to the cell assembly 210 so that the cell assembly 210 can be charged and discharged.

[0042] like Figure 2 As shown, in some embodiments, the charge / discharge circuit 100 includes a main positive switch 110, a fast charge positive switch 120, a main negative switch 130, a fast charge negative switch 140, a precharge / pre-discharge switch 150, a current-limiting resistor 170, and a switching switch 160. The charge / discharge circuit 100 is applied to the battery pack 200 to enable the battery pack 200 to be charged or discharged.

[0043] The first terminal of the main positive switch 110 is used to connect to the positive terminal of the battery cell assembly 210, and the first terminal of the main negative switch 130 is used to connect to the negative terminal of the battery cell assembly 210. The first terminal of the fast charging positive switch 120 is electrically connected to the second terminal of the main positive switch 110, and the second terminal of the fast charging positive switch 120 is used to connect to the positive terminal of the charging pile. The first terminal of the fast charging negative switch 140 is electrically connected to the second terminal of the main negative switch 130, and the second terminal of the fast charging negative switch 140 is used to connect to the negative terminal of the charging pile.

[0044] The first end of the precharge and pre-discharge switch 150 is electrically connected to the main positive switch 110, the first end of the current limiting resistor 170 is electrically connected to the second end of the precharge and pre-discharge switch 150, the first end of the switching switch 160 is electrically connected to the second end of the main positive switch 110, and the second end of the switching switch 160 is electrically connected to the second end of the current limiting resistor 170 and the second end of the fast charge positive switch 120.

[0045] The charging and discharging circuit 100 has a charging mode and a discharging mode. When the charging and discharging circuit 100 is in the charging mode, it charges the battery cell assembly 210. When the charging and discharging circuit 100 is in the discharging mode, the battery cell assembly 210 discharges to drive the motor or other electrical equipment on the vehicle.

[0046] When the charging / discharging circuit 100 starts the discharge mode, the fast charging positive switch 120 and the fast charging negative switch 140 remain open. First, the main negative switch 130 and the switching switch 160 are closed, and then the pre-charge / pre-discharge switch 150 is closed to perform pre-discharge. After the pre-charge / pre-discharge switch 150 has been closed for a period of time and the pre-discharge is complete, the main positive switch 110 is closed, and the pre-charge / pre-discharge switch 150 is opened. The main positive switch 110, the switching switch 160, and the main negative switch 130 can form a circuit to continuously discharge.

[0047] Understandably, the load side typically contains a large-capacity load capacitor, which initially has a voltage of 0V. If the high-voltage battery cell assembly 210 (e.g., 800V) is directly connected to the load capacitor via the main positive switch 110 and the main negative switch 130, the capacitor voltage cannot change abruptly. At the instant the switch is closed, the capacitor is essentially in a short-circuit state, which will generate a huge surge current. At the instant the switch is closed, the huge current will generate an electric arc, instantly melting or burning the switch contacts, thus impacting the main positive switch 110.

[0048] In this embodiment, the current-limiting resistor 170 can limit the current, establishing a high-resistance path between the cell assembly 210 and the load capacitor, limiting the initial discharge current. After the pre-charge and pre-discharge switch 150 is closed, the charge and discharge circuit 100 performs pre-discharge, causing the voltage of the load capacitor to rise gradually. This avoids the impact on the main positive switch 110 caused by directly closing it, thus protecting the main positive switch 110. As a result, the inrush current when the main positive switch 110 is closed is small, and the contact heating of the main positive switch 110 is small, meaning that sticking is less likely to occur.

[0049] When the charging / discharging circuit 100 starts charging mode, the switch 160 remains open. First, the main negative switch 130, fast-charging positive switch 120, and fast-charging negative switch 140 are closed. Then, the pre-charge / pre-discharge switch 150 is closed to initiate pre-charging. After the pre-charge / pre-discharge switch 150 has been closed for a period of time and pre-charging is complete, the main positive switch 110 is closed, and the pre-charge / pre-discharge switch 150 is opened. The fast-charging positive switch 120, main positive switch 110, main negative switch 130, and fast-charging negative switch 140 form a circuit for continuous charging.

[0050] Understandably, the boost module 181 typically includes a large-capacity bus capacitor, which has an initial voltage of 0V. If the high-voltage battery cell assembly 210 (e.g., 800V) is directly connected to the bus capacitor via the fast-charging positive switch 120 and the main negative switch 130, the capacitor voltage cannot change abruptly. At the instant the switch is closed, the capacitor is essentially in a short-circuit state, which will generate a huge surge current. At the instant the switch closes, the huge current will generate an electric arc, instantly melting or burning the switch contacts, thus impacting the fast-charging positive switch 120.

[0051] In this embodiment, the current-limiting resistor 170 can limit the current, establishing a high-resistance path between the battery cell assembly 210 and the charging pile, limiting the initial discharge current. After the pre-charge and pre-discharge switch 150 is closed, the charge and discharge circuit 100 performs pre-charge, causing the voltage of the bus capacitor to rise gradually. This avoids the impact on the fast-charging positive switch 120 caused by directly closing it, thus protecting the fast-charging positive switch 120. As a result, the inrush current when the fast-charging positive switch 120 is closed is small, and the contact heating of the fast-charging positive switch 120 is small, meaning that sticking is less likely to occur.

[0052] In summary, this embodiment changes the on / off state of the switching switch 160 so that the precharge / pre-discharge switch 150 can provide pre-discharge protection for the main positive switch 110 during discharge and pre-charge protection for the fast charge positive switch 120 during charging.

[0053] In some embodiments, when the charging / discharging circuit 100 is in discharge mode, and the differential voltage between the second terminal of the main positive switch 110 and the second terminal of the main negative switch 130 is less than or equal to a first threshold, the main positive switch 110 is closed and the precharge / pre-discharge switch 150 is open. The first threshold is relatively small and can be 5V, 10V, 15V, etc., and is not limited here.

[0054] By setting a first threshold, the voltage of the load capacitor rises to a level close to that of the cell assembly 210. The voltage difference between the load capacitor and the cell assembly 210 is already very small. Since the potential difference between the two ends of the main positive switch 110 (the voltage of the cell assembly 210 and the voltage of the load capacitor) is very small at this time, no large inrush current will be generated when the main positive switch 110 is closed.

[0055] When the charging / discharging circuit 100 is in charging mode, and the differential voltage between the second terminal of the fast charging positive switch 120 and the second terminal of the main negative switch 130 is less than or equal to the second threshold, the main positive switch 110 closes and the pre-charge / pre-discharge switch 150 opens. The second threshold is relatively small and can be 5V, 10V, 15V, etc., and is not limited here.

[0056] By setting a second threshold, the voltage of the bus capacitor rises to near the voltage of the cell assembly 210. The voltage difference between the bus capacitor and the cell assembly 210 is already very small. Since the potential difference between the two ends of the fast charging positive switch 120 (the voltage of the cell assembly 210 and the voltage of the bus capacitor) is very small at this time, no large inrush current will be generated when the fast charging positive switch 120 is closed.

[0057] In some embodiments, the main positive switch 110 can be a contactor, a MOSFET (metal-oxide-semiconductor field-effect transistor), an IGBT (insulated-gate bipolar transistor), a SiC MOSFET (silicon carbide metal-oxide-semiconductor field-effect transistor), a hybrid switch, etc.

[0058] The fast charging positive switch 120 can be a contactor, MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (insulated gate bipolar transistor), SiC MOSFET (silicon carbide metal-oxide-semiconductor field-effect transistor), hybrid switch, etc.

[0059] The main and negative switches 130 can be contactors, MOSFETs (metal-oxide-semiconductor field-effect transistors), IGBTs (insulated-gate bipolar transistors), SiC MOSFETs (silicon carbide metal-oxide-semiconductor field-effect transistors), hybrid switches, etc.

[0060] The fast-charging negative switch 140 can be a contactor, MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (insulated-gate bipolar transistor), SiC MOSFET (silicon carbide metal-oxide-semiconductor field-effect transistor), hybrid switch, etc.

[0061] The precharge and pre-discharge switch 150 can be a contactor, MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (insulated gate bipolar transistor), SiC MOSFET (silicon carbide metal-oxide-semiconductor field-effect transistor), hybrid switch, etc.

[0062] The changeover switch 160 can be a contactor, MOSFET (metal-oxide-semiconductor field-effect transistor), IGBT (insulated-gate bipolar transistor), SiC MOSFET (silicon carbide metal-oxide-semiconductor field-effect transistor), hybrid switch, etc.

[0063] like Figure 3 As shown, in some embodiments, the charging and discharging circuit 100 further includes a boost module 181. The first input terminal of the boost module 181 is used to connect to the positive terminal of the charging pile, the second input terminal of the boost module 181 is used to connect to the negative terminal of the charging pile, the first output terminal of the boost module 181 is used to connect to the second terminal of the fast charging positive switch 120, and the second output terminal of the boost module 181 is used to connect to the second terminal of the fast charging negative switch 140.

[0064] It is understandable that there are a large number of 400V / 500V public fast charging stations on the market. If an 800V battery pack is directly connected to a 400V charging station, the charging current will be very small, or even unable to charge, because the battery voltage is higher than the charging station voltage.

[0065] The boost module 181 can actively boost the lower voltage (e.g., 400V) provided by the charging station to the higher voltage (e.g., 800V) required to match the battery pack 200. In this way, the 800V battery pack 200 can achieve efficient fast charging on 400V charging stations, breaking down the voltage platform barrier, making the vehicle backward compatible with mainstream charging facilities, and expanding the range of available fast charging networks.

[0066] When the battery pack 200 needs to discharge externally, the high voltage of the battery (e.g., 800V) needs to be reduced to the standard voltage of the load or the power grid. At this time, the boost module 181 operates in reverse, becoming a buck module to achieve energy output.

[0067] like Figure 4 As shown, in some embodiments, the charging and discharging circuit 100 further includes a current sensor 182, the first end of which is electrically connected to the second end of the main negative switch 130, and the second end of which is electrically connected to the first end of the fast charging negative switch 140.

[0068] During charging or discharging, if the current exceeds the safety limits of the battery, wiring harness, or electronic components due to a short circuit or other reasons, the current sensor 182 will immediately detect this abnormality. The current sensor 182 can quickly send a signal to the battery management system (BMS), and the BMS will disconnect the main positive switch 110 and the main negative switch 130 within milliseconds to cut off the circuit and prevent fire or equipment damage.

[0069] The current sensor 182 can also be used to calculate the power of the battery cell assembly 210, reflecting the lifespan and aging degree of the battery cell assembly 210.

[0070] Based on the real-time current feedback from the current sensor 182, the BMS can predict the battery's heat generation power. If the current is high, the BMS will proactively increase the cooling system's power to prevent the battery from overheating; otherwise, it will reduce the cooling power to save energy.

[0071] The current sensor 182 can distinguish the direction of current flow. Current flowing out of the battery is used to drive the vehicle or discharge externally. Current flowing into the battery comes from a charging station or energy recovery, which allows the BMS to distinguish what operating mode the vehicle is in.

[0072] like Figure 5 As shown, in some embodiments, the charging and discharging circuit 100 further includes a first motor controller 191, which can be used to control a front-drive motor or a rear-drive motor. The first terminal of the first motor controller 191 is electrically connected to the second terminal of the switching switch 160, and the second terminal of the first motor controller 191 is electrically connected to the second terminal of the main negative switch 130.

[0073] The first motor controller 191 contains a bus capacitor. The charging and discharging circuit 100 can precharge the bus capacitor. The current-limiting resistor 170 and the precharge and pre-discharge switch 150 limit the current charging of the capacitor inside the first motor controller 191, which can protect the main positive switch 110.

[0074] The first motor controller 191 can convert the DC power provided by the battery cell assembly 210 into the three-phase AC power required to drive the motor, and precisely control the frequency and amplitude of the AC power, thereby controlling the speed and torque of the motor to achieve vehicle acceleration, deceleration and cruising.

[0075] The first motor controller 191 can also rectify the three-phase AC power generated by the motor into DC power and recharge the battery pack 200. When the vehicle is coasting or braking, the wheels drag the motor to rotate, temporarily turning the motor into a generator.

[0076] Energy recovery can improve a vehicle's energy efficiency, extend its driving range, and reduce wear on mechanical brakes.

[0077] When the vehicle needs external power, the first motor controller 191 inverts the DC power from the battery into AC power for output.

[0078] Optionally, the first motor controller 191 is integrated into the battery pack 200 or a similar charging and discharging circuit 100, which is beneficial to the overall vehicle design, shortens the length of the bulky high-voltage DC wiring harness between the battery pack 200 and the motor controller, reduces resistance, reduces transmission loss, reduces weight, saves space and cost, and makes the layout more compact.

[0079] like Figure 6 As shown, in some embodiments, the charging and discharging circuit 100 further includes a second motor controller 192, the first terminal of which is electrically connected to the second terminal of the switching switch 160, and the second terminal of which is electrically connected to the second terminal of the main negative switch 130.

[0080] The advantages of setting up a second motor controller 192 can be found in the first motor controller 191, and will not be repeated here.

[0081] One of the second motor controller 192 and the first motor controller 191 is used to control the front drive motor, while the other is used to control the rear drive motor. The two motors can work together, and their combined output power and torque are greater than that of a single motor. When overtaking at high speed or climbing hills, the dual motors can provide sufficient power reserves.

[0082] Furthermore, because each motor can independently and precisely control the torque output of its corresponding axle, the system can apply greater torque to the outer wheels and less torque to the inner wheels, or even recover energy, during cornering. This generates a "yaw moment" that helps the vehicle steer, making cornering more agile and stable, and reducing understeer. On wet or low-traction surfaces, the system can instantly adjust the torque in the front-to-rear and left-to-right directions to prevent wheel slippage and improve handling limits.

[0083] When cruising on smooth city roads or at high speeds, only one motor (usually the front axle motor) with a higher efficiency range can be used for driving, while the other motor can be completely shut down to avoid idling losses, thus achieving a low energy consumption level similar to that of a single-motor vehicle. When high power is needed, the other motor can be started to output power together, allowing dual-motor vehicles to achieve both strong performance and a very considerable driving range, resolving the contradiction between performance and energy consumption.

[0084] Finally, if one of the motors or controllers fails, the other motor can drive the vehicle independently, ensuring that the vehicle does not completely break down and can be safely driven to a repair shop, providing drive redundancy and improving safety.

[0085] like Figure 7 As shown, in some embodiments, the charging and discharging circuit 100 further includes a conductive element 183. The first end of the conductive element 183 is electrically connected to the second end of the precharge and pre-discharge switch 150, and the second end of the conductive element 183 is electrically connected to the second end of the fast charge positive switch 120. The conductive element 183 can be, for example, a wire, a conductive sheet, a conductive post, etc., and can be selected according to actual needs.

[0086] The rated current of the conductive element 183 is compatible with the rated current of the precharge and pre-discharge switch 150. The overcurrent of the precharge and pre-discharge switch 150 is relatively small. Therefore, the conductive element 183 can be made of wire with similar overcurrent capacity, that is, relatively thin wire, in order to save costs, reduce weight and reduce space occupation.

[0087] In some embodiments, the battery pack 200 further includes a control unit, which is electrically connected to the controlled terminals of the main positive switch 110, the fast charging positive switch 120, the main negative switch 130, the fast charging negative switch 140, the pre-charge / pre-discharge switch 150, and the switching switch 160. The control unit can control the on / off states of the main positive switch 110, the fast charging positive switch 120, the main negative switch 130, the fast charging negative switch 140, the pre-charge / pre-discharge switch 150, and the switching switch 160. The control unit can be, exemplarily, a BMS (Battery Management System). By controlling each switch, the battery pack 200 can automatically perform pre-charging and pre-discharging, thereby improving the vehicle's intelligence level.

[0088] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A charging and discharging circuit, characterized in that, include: A main positive switch, the first end of which is used to connect to the positive terminal of the battery cell assembly; A fast charging positive switch, wherein the first end of the fast charging positive switch is electrically connected to the second end of the main positive switch, and the second end of the fast charging positive switch is used to connect to the positive terminal of the charging pile; A main negative switch, the first end of which is used to connect to the negative terminal of the battery cell assembly; A fast charging negative switch, wherein the first end of the fast charging negative switch is electrically connected to the second end of the main negative switch, and the second end of the fast charging negative switch is used to connect to the negative terminal of the charging pile; A precharge / pre-discharge switch, the first terminal of which is electrically connected to the main positive switch; A current-limiting resistor, the first end of which is electrically connected to the second end of the precharge and pre-discharge switch; A switching switch is provided, wherein the first end of the switching switch is electrically connected to the second end of the main positive switch, and the second end of the switching switch is electrically connected to the second end of the current limiting resistor and the second end of the fast charging positive switch.

2. The charging and discharging circuit according to claim 1, characterized in that, The charging and discharging circuit also includes a boost module. The first input terminal of the boost module is used to connect to the positive terminal of the charging pile, the second input terminal of the boost module is used to connect to the negative terminal of the charging pile, the first output terminal of the boost module is used to connect to the second terminal of the fast charging positive switch, and the second output terminal of the boost module is used to connect to the second terminal of the fast charging negative switch.

3. The charging and discharging circuit according to claim 1, characterized in that, The charging and discharging circuit also includes a current sensor, the first end of which is electrically connected to the second end of the main negative switch, and the second end of which is electrically connected to the first end of the fast charging negative switch.

4. The charging and discharging circuit according to claim 1, characterized in that, The charging and discharging circuit further includes a first motor controller, the first terminal of which is electrically connected to the second terminal of the switching switch, and the second terminal of which is electrically connected to the second terminal of the main negative switch.

5. The charging and discharging circuit according to claim 4, characterized in that, The charging and discharging circuit also includes a second motor controller, the first terminal of which is electrically connected to the second terminal of the switching switch, and the second terminal of which is electrically connected to the second terminal of the main negative switch.

6. The charging and discharging circuit according to claim 1, characterized in that, The charging and discharging circuit also includes a conductive component. The first end of the conductive component is electrically connected to the second end of the precharge and pre-discharge switch, and the second end of the conductive component is electrically connected to the second end of the fast charge positive switch. The rated current of the conductive component is adapted to the rated current of the precharge and pre-discharge switch.

7. The charging and discharging circuit according to claim 1, characterized in that, The charging and discharging circuit has a discharging mode and a charging mode. When the charging and discharging circuit is in discharge mode, and the differential voltage between the second terminal of the main positive switch and the second terminal of the main negative switch is less than or equal to the first threshold, the main positive switch is closed and the pre-charge and pre-discharge switch is open. When the charging and discharging circuit is in charging mode, and the differential voltage between the second terminal of the fast charging positive switch and the second terminal of the main negative switch is less than or equal to the second threshold, the main positive switch is closed and the pre-charge and pre-discharge switch is opened.

8. A battery pack, characterized in that, include: The charging and discharging circuit as described in any one of claims 1-7; as well as A battery cell assembly, wherein the positive terminal of the battery cell assembly is electrically connected to the first terminal of the main positive switch, and the negative terminal of the battery cell assembly is electrically connected to the first terminal of the main negative switch.

9. The battery pack according to claim 8, characterized in that, The battery pack also includes a control unit, which is electrically connected to the controlled terminals of the main positive switch, the fast charging positive switch, the main negative switch, the fast charging negative switch, the pre-charge and pre-discharge switch, and the switching switch. The control unit is capable of controlling the on / off state of the main positive switch, the fast charging positive switch, the main negative switch, the fast charging negative switch, the pre-charge and pre-discharge switch, and the switching switch.

10. A vehicle, characterized in that, Includes the battery pack as described in claim 8 or 9.

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