Battery charging and discharging circuit, system and electric vehicle

Abstract

The application provides a battery charging and discharging circuit, system and electric vehicle. After determining that each battery cell is normal, if a charging instruction is received and it is judged that each parallel relay is not stuck, a control unit outputs a first instruction; a series-parallel switching unit receives the first instruction and outputs a series signal to control each series relay to be closed and each parallel relay to be opened, so that each battery module is charged in series; if a discharging instruction is received and it is judged that each series relay is not stuck, the control unit outputs a second instruction; the series-parallel switching unit receives the second instruction and outputs a parallel signal to control each parallel relay to be closed and each series relay to be opened, so that each battery module is discharged in parallel. When charging, the circuit can connect multiple battery modules in series, increase the charging voltage, reduce the charging current and improve the charging speed; when discharging, the circuit can connect multiple battery modules in parallel and reduce the system voltage, so that the requirement for the voltage resistance performance of the whole vehicle can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, in particular to a battery charging and discharging circuit, system and electric vehicle. BACKGROUND

[0002] With the progress of electric vehicle battery technology, to solve the problem of slow charging speed of new energy electric vehicles, in the related art, the charging speed can be increased by increasing the charging current, but as the charging current increases, the high-voltage cable used increases exponentially, and the single-gun charging of the national standard charging pile has a maximum charging current of 250A regardless of the voltage. The charging speed can also be increased by increasing the charging voltage, but this method requires higher and higher insulation performance of the vehicle, and the vehicle's voltage resistance performance is also increasingly demanding. Therefore, for the problem of slow charging speed of electric vehicles, the related art lacks an effective electric vehicle charging solution. SUMMARY

[0003] The purpose of the present application is to provide a battery charging and discharging circuit, system and electric vehicle to improve the charging speed of electric vehicles.

[0004] The battery charging and discharging circuit provided by the present application comprises a control unit for determining whether each cell in the module unit is normal, and if a charging instruction is received, determining whether each parallel relay in the module unit is stuck, and if not, outputting a first instruction; wherein the module unit comprises a plurality of battery modules, the plurality of battery modules are physically connected through a plurality of series relays and a plurality of parallel relays, each battery module comprises a plurality of cells; the plurality of series relays are used to connect each battery module in series; the plurality of parallel relays are used to connect each battery module in parallel; a series-parallel switching unit is used to receive the first instruction and output a series signal according to the first instruction to control each series relay to close and each parallel relay to open, so as to charge each battery module in series; the control unit is also used to determine whether each series relay in the module unit is stuck if a discharging instruction is received, and if not, output a second instruction; the series-parallel switching unit is also used to receive the second instruction and output a parallel signal according to the second instruction to control each parallel relay to close and each series relay to open, so as to discharge each battery module in parallel.

[0005] Further, the control unit comprises: a slave module, configured to collect target data of each battery cell in the module unit, and send the target data to the master module; the master module is configured to confirm that each battery cell is normal if it is confirmed that the target data of the battery cell is normal; and the master module is further configured to output a first instruction if no sticking is found in each parallel relay in the module unit when receiving a charging instruction, and output a second instruction if no sticking is found in each series relay in the module unit when receiving a discharging instruction.

[0006] Further, the target data comprises temperature data and voltage data; and the master module is further configured to confirm that each battery cell is normal if it is confirmed that the temperature data of the battery cell does not exceed a preset temperature threshold and the voltage data of the battery cell is not lower than a preset voltage threshold.

[0007] Further, the series-parallel switching unit comprises: a power supply having a positive terminal and a negative terminal, the negative terminal being connected to a negative end of a coil in each series relay and to a negative end of a coil in each parallel relay; a total relay having a first end, a second end and a coil end; the first end of the total relay being connected to the positive terminal of the power supply, and the coil end of the total relay being connected to the master module; the first end and the second end of the total relay being closed if the first instruction or the second instruction is received through the coil end of the total relay; a switching switch module having a first end, a second end, a third end and a coil end; the first end of the switching switch module being connected to the second end of the total relay, the second end of the switching switch module being connected to a positive end of the coil in each series relay, the third end of the switching switch module being connected to a positive end of the coil in each parallel relay, and the coil end of the switching switch module being connected to the master module; the first end of the switching switch module being connected to the second end of the switching switch module to control each series relay to be closed if the first instruction is received through the coil end of the switching switch module; and the first end of the switching switch module being connected to the third end of the switching switch to control each parallel relay to be closed if the second instruction is received through the coil end of the switching switch module.

[0008] Further, in the module unit, the positive terminal of the first battery module is connected to a total positive terminal of the battery, the positive terminal of each battery module other than the first battery module is physically connected to the total positive terminal of the battery through a corresponding first relay, the negative terminal of the last battery module is connected to a total negative terminal of the battery, and the negative terminal of each battery module other than the last battery module is physically connected to the total negative terminal of the battery through a corresponding second relay.

[0009] Further, the plurality of parallel relays comprises each first relay and each second relay.

[0010] Further, one series relay is connected between each adjacent two battery modules.

[0011] Further, the plurality of battery cells in each battery module are connected in series and / or parallel in a preset manner.

[0012] The application provides a battery charging and discharging system, which comprises the battery charging and discharging circuit.

[0013] The application provides an electric vehicle, which comprises the battery charging and discharging system.

[0014] The battery charging and discharging circuit, system and electric vehicle provided by the application, the circuit comprises: a control unit, which is used for, if a charging instruction is received under the condition that each battery cell in a module unit is normal, judging whether each parallel relay in the module unit is stuck, and outputting a first instruction if no sticking is found; wherein the module unit comprises a plurality of battery modules, the plurality of battery modules are physically connected through a plurality of series relays and a plurality of parallel relays, and each battery module comprises a plurality of battery cells; the plurality of series relays are used for connecting each battery module in series; the plurality of parallel relays are used for connecting each battery module in parallel; a series-parallel switching unit is used for receiving the first instruction, outputting a series signal according to the first instruction, controlling each series relay to be closed and each parallel relay to be disconnected, and charging each battery module in series; and the control unit is also used for, if a discharging instruction is received, judging whether each series relay in the module unit is stuck, and outputting a second instruction if no sticking is found; and the series-parallel switching unit is also used for receiving the second instruction, outputting a parallel signal according to the second instruction, controlling each parallel relay to be closed and each series relay to be disconnected, and discharging each battery module in parallel. When charging, the circuit can connect the plurality of battery modules in series, increase the charging voltage, reduce the charging current and improve the charging speed; and when discharging, the circuit can connect the plurality of battery modules in parallel and reduce the system voltage, so that the requirement for the voltage resistance performance of the whole vehicle can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0016] Figure 1 A schematic diagram of a battery charging and discharging circuit provided by the embodiment of the application;

[0017] Figure 2 A schematic diagram of a module unit provided by the embodiment of the application;

[0018] Figure 3 A schematic diagram of a battery module series provided for an embodiment of the present application is shown in the following figure:

[0019] Figure 4 A schematic diagram of a battery module parallel provided for an embodiment of the present application is shown in the following figure:

[0020] Figure 5 A schematic diagram of a series-parallel switching unit provided for an embodiment of the present application is shown in the following figure:

[0021] Figure 6 A schematic diagram of a battery charging and discharging system provided for an embodiment of the present application is shown in the following figure. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0023] In the related art, there is a lack of effective electric vehicle charging solutions to address the slow charging speed of electric vehicles. Based on this, the embodiments of the present application provide a battery charging and discharging circuit, system and electric vehicle, which can be applied to applications requiring charging and discharging of electric vehicles.

[0024] To facilitate the understanding of the present embodiment, first introduce a battery charging and discharging circuit disclosed by the embodiments of the present application, as shown in the following figure, the circuit comprises: control unit 10, series-parallel switching unit 11 and module unit 12 connected in turn; the control unit 10 is also connected with the module unit 12. Figure 1

[0025] The control unit 10 is used to determine that each cell in the module unit 12 is normal, and if a charging instruction is received, determine whether each parallel relay in the module unit 12 is stuck, and if not, output a first instruction; wherein the module unit 12 includes a plurality of battery modules, the plurality of battery modules are physically connected through a plurality of series relays and a plurality of parallel relays, each battery module includes a plurality of cells; the plurality of series relays are used to make each battery module in series; the plurality of parallel relays are used to make each battery module in parallel;

[0026] ​The module unit 12 is generally composed of a plurality of battery modules, each of which generally includes a plurality of battery cells; the battery cell refers to a single electrochemical cell containing a positive electrode and a negative electrode, which is the power storage part in the battery module; the charging instruction can be understood as an instruction received by the control unit 10 when the vehicle is in a charging preparation state, which indicates that the vehicle is in a charging preparation state and needs to be charged; the module unit 12 generally includes a plurality of parallel relays and a plurality of series relays, when each parallel relay is closed, each battery module is connected in parallel, and when each series relay is closed, each battery module is connected in series; in actual implementation, the control unit 10 starts to work after receiving the wake-up power of the vehicle, which can include low-voltage power and 12V auxiliary power, such as low-voltage power on the key; after the control unit 10 starts to work, it generally first determines whether each battery cell in each battery module is in a normal state, such as whether there is a problem of excessively high temperature, excessively low voltage, etc., and after confirming that each battery cell is normal, if a charging instruction is received, it is generally necessary to perform a sticking detection on each parallel relay in the module unit 12, which specifically refers to detecting whether the relay contact of each parallel relay is stuck due to long-term use or overload, i.e. the state of contact sticking; the purpose of the sticking detection is to ensure the safe operation of the circuit and avoid circuit failure or safety hazards caused by relay contact sticking; when the control unit 10 confirms that each parallel relay is not stuck, it can output a first instruction and send the first instruction to the series-parallel connection switching unit 11.

[0027] The series-parallel connection switching unit 11 is configured to receive the first instruction, output a series connection signal according to the first instruction, control each series relay to be closed and each parallel relay to be disconnected, and charge each battery module in series.

[0028] In actual implementation, when the series-parallel connection switching unit 11 receives the first instruction, it can output a series connection signal and send the series connection signal to the module unit 12, so that each series relay in the module unit 12 is closed and each parallel relay is disconnected; after each series relay is closed, each battery module is connected in series, and series charging of each battery module is realized.

[0029] The control unit 10 is further configured to, if a discharging instruction is received, determine whether each series relay in the module unit 12 is stuck, and output a second instruction if there is no sticking.

[0030] The control unit 10 confirms that each battery cell is normal, and if a discharge instruction is received, it is usually necessary to perform a sticking detection on each series relay in the module unit 12, that is, to detect whether the relay contact of each series relay is stuck due to long-term use or overload, that is, the state of contact sticking; when the control unit 10 confirms that each series relay is not stuck, it can output a second instruction and send the second instruction to the series-parallel switching unit 11.

[0031] The series-parallel switching unit 11 is also used to receive the second instruction, output a parallel signal according to the second instruction, control each parallel relay to be closed and each series relay to be opened, and perform parallel discharge on each battery module.

[0032] In actual implementation, when the series-parallel switching unit 11 receives the above-mentioned second instruction, it can output a parallel signal and send the parallel signal to the module unit 12, so that each parallel relay in the module unit 12 is closed and each series relay is opened; after each parallel relay is closed, each battery module is connected in parallel, and parallel discharge is performed on each battery module.

[0033] The above-mentioned battery charging and discharging circuit can make a plurality of battery modules connected in series during charging, increase the charging voltage, reduce the charging current, and improve the charging speed; during discharging, the plurality of battery modules can be connected in parallel to reduce the system voltage, so that the requirement for the voltage resistance performance of the whole vehicle can be reduced.

[0034] Further, the control unit includes a slave module and a master module; the slave module is used to collect target data of each battery cell in the module unit and send the target data to the master module; the master module is used to confirm that each battery cell is normal if the target data of the battery cell is normal; and is also used to output a first instruction if each parallel relay in the module unit is not stuck when a charging instruction is received, and output a second instruction if each series relay in the module unit is not stuck when a discharging instruction is received.

[0035] In actual implementation, the slave module and the master module in the control unit can receive the wake-up power supply of the whole vehicle. After receiving the wake-up power supply, the master module and the slave module can start to work. After the slave module starts to work, it usually collects target data of each battery cell in each battery module, which can be used to indicate whether the working state of the battery cell is normal. The collected target data is uploaded to the master module. The master module can analyze whether each battery cell is normal according to the received target data of each battery cell. Specifically, if the target data corresponding to the battery cell is normal, it can be determined that the battery cell is normal. If the target data corresponding to the battery cell is abnormal, it can be determined that the battery cell is abnormal. When it is determined that each battery cell is normal, the master module can receive the charging instruction or the discharging instruction and perform adhesion detection on the corresponding relay to output the corresponding first instruction or second instruction.

[0036] Further, the target data includes temperature data and voltage data. The master module is further configured to determine that each battery cell is normal if it is determined that the temperature data of the battery cell does not exceed a preset temperature threshold and the voltage data of the battery cell is not lower than a preset voltage threshold.

[0037] The preset temperature threshold and the preset voltage threshold can be set according to actual needs. In actual implementation, the slave module can collect the temperature data and the voltage data of each battery cell and upload them to the master module. The master module can determine whether the temperature data of each battery cell exceeds the preset temperature threshold. If the temperature data exceeds the preset temperature threshold, it is usually considered that the temperature of the battery cell is too high and there is a risk of burning. At the same time, it can be determined whether the voltage data of the battery cell is lower than the preset voltage threshold. For example, the voltage data of most battery cells is 3.2V, but the voltage data of the battery cell is 2V, that is, the voltage data of the battery cell is too low. When the temperature data and / or the voltage data of a battery cell are abnormal, it is usually considered that the battery cell is abnormal. Only when the temperature data and the voltage data of the battery cell are normal, it is considered that the battery cell is normal.

[0038] Further, the series-parallel switching unit includes a power supply, a total relay and a switching switch module. The power supply has a positive terminal and a negative terminal. The negative terminal is connected to the negative end of the coil in each series relay and to the negative end of the coil in each parallel relay. The voltage value of the power supply can be set according to actual needs, such as a 24V power supply. The negative terminal of the power supply is connected to the negative end of the coil in each series relay in the module unit and to the negative end of the coil in each parallel relay.

[0039] The total relay has a first end, a second end and a coil end; the first end of the total relay is connected to the positive end of the power supply, and the coil end of the total relay is connected to the master control module; and the total relay is used to close the first end and the second end of the total relay if a first instruction or a second instruction is received through the coil end of the total relay; in actual implementation, the coil end of the total relay includes a coil positive end and a coil negative end, the coil positive end and the coil negative end are connected to the master control module, and the first instruction and the second instruction sent by the master control module can be sent to the coil positive end and the coil negative end; when the coil positive end and the coil negative end of the total relay receive the first instruction or the second instruction, an electric current will flow in the coil, so that the first end and the second end of the total relay are attracted.

[0040] The switching switch module has a first end, a second end, a third end and a coil end; the first end of the switching switch module is connected to the second end of the total relay, the second end of the switching switch module is connected to the coil positive end of each series relay, the third end of the switching switch module is connected to the coil positive end of each parallel relay, and the coil end of the switching switch module is connected to the master control module; and the switching switch module is used to control the first end of the switching switch module to be connected to the second end of the switching switch module to control each series relay to be closed if a first instruction is received through the coil end of the switching switch module, and control the first end of the switching switch module to be connected to the third end of the switching switch to control each parallel relay to be closed if a second instruction is received through the coil end of the switching switch module.

[0041] The switching switch module can realize switching between the second end and the third end of the switching switch module through a single-pole double-throw switch; the coil end of the switching switch module includes a coil positive end and a coil negative end, the coil positive end and the coil negative end are connected to the master control module, and the first instruction and the second instruction sent by the master control module can be sent to the coil positive end and the coil negative end; in specific implementation, when the coil positive end and the coil negative end of the switching switch module receive the first instruction, the first end of the switching switch module can be connected to the second end of the switching switch module; since the second end of the switching switch module is connected to the coil positive end of each series relay, the power supply can supply power to the coil in each series relay, so that an electric current flows in the coil, thereby causing each series relay to be attracted, and each battery module can be charged in series. When the coil positive end and the coil negative end of the switching switch module receive the second instruction, the first end of the switching switch module can be connected to the third end of the switching switch module; since the third end of the switching switch module is connected to the coil positive end of each parallel relay, the power supply can supply power to the coil in each parallel relay, so that an electric current flows in the coil, thereby causing each parallel relay to be attracted, and each battery module can be discharged in parallel.

[0042] Further, in the module unit, the positive electrode of the first battery module is connected to the battery total positive terminal, the positive electrode of each battery module other than the first battery module is respectively connected to the battery total positive terminal through a corresponding first relay; the negative electrode of the last battery module is connected to the battery total negative terminal, the negative electrode of each battery module other than the last battery module is respectively connected to the battery total negative terminal through a corresponding second relay; the parallel relays include each first relay and each second relay.

[0043] The battery total positive terminal and the battery total negative terminal can be understood as two key components for the entire battery charging and discharging in the entire module unit; specifically, during the charging process of each battery module in the module unit, the battery total positive terminal and the battery total negative terminal function to transmit current from the charger into the module unit; during the battery discharging process, the battery total positive terminal and the battery total negative terminal function to convert the internal energy of the module unit into current output to provide power for the driving of the vehicle. Each first relay and each second relay collectively serve as the above-mentioned multiple parallel relays.

[0044] Further, a series relay is connected between each adjacent two battery modules. Specifically, a series relay is connected between the negative electrode of the first battery module and the positive electrode of the second battery module, a series relay is connected between the negative electrode of the second battery module and the positive electrode of the third battery module, and so on, so that when each series relay is attracted, the series connection of multiple battery modules can be achieved.

[0045] Further, the multiple battery cells in each battery module are connected in series and / or parallel in a preset manner; the preset manner can be set according to actual needs, for example, a x-parallel-y-series form can be used, etc., wherein the values of x and y can be set according to actual needs, which are not limited herein; the number of battery cells and the connection manner of battery cells in each battery module are usually the same.

[0046] For ease of understanding, refer to Figure 2 a schematic diagram of a module unit, which takes four battery modules as an example to illustrate the way of sticking detection of relays, as shown in Figure 2As shown, in all relay open cases, if the voltage detected between points A, F is consistent with battery module 1, it is confirmed that K1 relay is stuck; otherwise K1 relay is normal. If the voltage detected between points B, F is consistent with battery module 2, it is confirmed that K2 relay is stuck; otherwise K2 relay is normal. If the voltage detected between points C, F is consistent with battery module 3, it is confirmed that K3 relay is stuck; otherwise K3 relay is normal. If the voltage detected between points B, E is consistent with battery module 1, it is confirmed that P1 relay is stuck; otherwise P1 relay is normal. If the voltage detected between points C, E is consistent with battery module 1, P2 relay is stuck; otherwise P2 relay is normal. If the voltage detected between points D, E is consistent with battery module 1, it is confirmed that P3 relay is stuck; otherwise P3 relay is normal. If the voltage detected between points A, B is consistent with battery module 1, it is confirmed that X1 relay is stuck; otherwise X1 relay is normal. If the voltage detected between points B, C is consistent with battery module 2, it is confirmed that X2 relay is stuck; otherwise X2 relay is normal. If the voltage detected between points C, D is consistent with battery module 3, it is confirmed that X3 relay is stuck; otherwise X3 relay is normal. Figure 2 In the embodiment, the battery cells in the battery module 1, the battery module 2, the battery module 3 and the battery module 4 can all be in the form of x parallel y series.

[0047] Figure 2 In the embodiment, the X1 relay, the X2 relay and the X3 relay are a group of relays, referred to as series relays; the K1 relay, the K2 relay, the K3 relay, the P1 relay, the P2 relay and the P3 relay are a group of relays, referred to as parallel relays; therefore, in order to control the series-parallel state of the battery modules, it is only necessary to control the states of the series relays and the parallel relays.

[0048] Referring to Figure 3 a schematic diagram of a battery module series connection, in combination with Figure 2 In this state, the X1 relay, the X2 relay and the X3 relay are all closed, and the K1 relay, the K2 relay, the K3 relay, the P1 relay, the P2 relay and the P3 relay need to be all opened. The series-parallel state of the whole system is x parallel 4 y series.

[0049] Referring to Figure 4 a schematic diagram of a battery module parallel connection, in combination with Figure 2 In this state, the X1 relay, the X2 relay and the X3 relay are all opened, and the K1 relay, the K2 relay, the K3 relay, the P1 relay, the P2 relay and the P3 relay need to be all closed. The series-parallel state of the whole system is 4 x parallel y series.

[0050] In the whole system, the series relay and the parallel relay are not allowed to be closed at the same time in any case. Once the simultaneous closing occurs, the battery module will be short-circuited, and the whole battery or even the vehicle will be damaged. Therefore, in order to ensure safety, a series-parallel switching unit as shown in Figure 5 is provided, that is, a circuit as shown in Figure 5 is added to the control loop of the series relay and the parallel relay. When the parallel relay needs to be closed, the master control module closes the K relay; when the series relay needs to be closed, the master control module closes the K relay and the X relay. In the whole system, no matter whether the K relay and the X relay are in the closed or open state, the simultaneous closing of the parallel relay and the series relay will not occur.

[0051] Specifically, during discharging, the vehicle sends the discharging state to the master control module through communication. The master control module first completes the adhesion detection of the related relays, and closes the K relay in the case that no adhesion is confirmed, so as to close the parallel relay. During charging, after the master control module detects the charging pile connection signal, the master control module first completes the adhesion detection of the related relays, and closes the K relay and the X relay in the case that no adhesion is confirmed, so as to close the series relay.

[0052] The above battery charging and discharging circuit changes the state of the multiple battery modules to series through control of the relays during charging, so as to increase the battery voltage and reduce the charging current. During discharging, the state of the battery modules is changed to parallel through control of the relays, so as to reduce the discharging voltage.

[0053] The embodiment of the application provides a battery charging and discharging system, which comprises the battery charging and discharging circuit of any one of the above.

[0054] Referring to Figure 6 , a schematic diagram of a battery charging and discharging system is shown. The working process of the whole system is as follows:

[0055] 1. The master control module and the slave control module receive the wake-up power supply of the vehicle, and start to work.

[0056] 2. The slave control module collects the temperature data and the voltage data of each battery cell, and uploads the data to the master control module.

[0057] 3. The master control module judges whether the battery cell has a burning problem according to whether the temperature data is too high, and judges whether the battery cell is abnormal according to whether the voltage data is too low (for example, most battery cells have a voltage of 3.2V, but an individual battery cell has a voltage of 2.0V).

[0058] 4、If the battery cell is normal, the main control module detects the relay sticking according to the voltage data of the battery cell. The main control module accumulates the data of the battery cells in the same battery module to obtain the voltage of the current module, and compares it with the voltage of the monitoring point (for example, the voltage between points A and F). If the voltage of the monitoring point reaches 90% of the voltage of the current module, it is judged that the corresponding relay is stuck.

[0059] 5、If the main control module receives that the whole vehicle is in the discharging state, the main control module only needs to judge whether the X1 relay, the X2 relay and the X3 relay are stuck or not, and if not, the main control module closes the K relay.

[0060] 6、If the main control module receives that the whole vehicle is in the charging state, the main control module only needs to judge whether the K1 relay, the K2 relay, the K3 relay, the P1 relay, the P2 relay and the P3 relay are stuck or not, and if not, the main control module closes the K relay and the X relay.

[0061] The above battery charging and discharging system can change the connection state of the battery module to make multiple battery modules in series, increase the charging voltage, improve the system voltage, reduce the charging current, and separate the charging loop when charging under the condition of meeting the power of the whole vehicle, so that the normal use of the whole vehicle can be met, the charging speed can be improved, and only the insulation performance of the charging part needs to be increased. In the discharging condition, multiple battery modules are connected in parallel, the system voltage is reduced, and the voltage withstand level requirement of other parts of the whole vehicle is reduced. The system is more suitable for the charging pile in the existing market.

[0062] The voltage platform of the vehicle in the current market is generally 500V, and the voltage output of the charging pile can reach 1000V, but the maximum output current is limited to 250A. The system can effectively use the power of the charging pile and increase the charging speed of the vehicle by adjusting the series and parallel connection of the battery module to change the battery state.

[0063] The embodiment of the application provides an electric vehicle comprising the above battery charging and discharging system.

[0064] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A battery charging and discharging circuit, characterized in that: The circuit comprises: A control unit, configured to, upon determining that each battery cell in the module unit is normal, determine whether each parallel relay in the module unit is stuck if a charging instruction is received, and output a first instruction if no sticking occurs; wherein the module unit includes a plurality of battery modules, the plurality of battery modules are physically connected via a plurality of series relays and a plurality of parallel relays, and each battery module includes a plurality of battery cells; the plurality of series relays are configured to connect each of the battery modules in series; and the plurality of parallel relays are configured to connect each of the battery modules in parallel; a series-parallel switching unit, configured to receive the first instruction and output a series signal according to the first instruction to control each of the series relays to be closed and each of the parallel relays to be opened, so as to charge each battery module in series; The control unit is further configured to, upon receiving a discharge instruction, determine whether each series relay in the module unit is stuck, and output a second instruction if no sticking occurs; The series-parallel switching unit is further configured to receive the second instruction and output a parallel signal according to the second instruction to control each of the parallel relays to be closed and each of the series relays to be opened, so as to discharge each of the battery modules in parallel; The control unit comprises: A slave control module is used to collect target data of each battery cell in the module unit and send the target data to the master control module; The main control module is configured to, for each battery cell, determine if the target data of the battery cell are all normal and confirm that the battery cell is normal; further configured to, upon receiving a charge instruction, determine whether each parallel relay in the module unit is stuck, and if not, output a first instruction; upon receiving a discharge instruction, determine whether each series relay in the module unit is stuck, and if not, output a second instruction; The series-parallel switching unit includes: A power supply having a positive terminal and a negative terminal, wherein the negative terminal is connected to the negative terminal of the coil in each of the series relays and to the negative terminal of the coil in each of the parallel relays; a main relay, comprising a first end, a second end, and a coil end; the first end of the main relay being connected to the positive terminal of the power supply, and the coil end of the main relay being connected to the main control module; and configured to close the first end and the second end of the main relay if the first instruction or the second instruction is received through the coil end of the main relay; A switching switch module having a first end, a second end, a third end, and a coil end; the first end of the switching switch module is connected to the second end of the main relay, the second end of the switching switch module is connected to the positive end of the coil of each of the series relays, the third end of the switching switch module is connected to the positive end of the coil of each of the parallel relays, and the coil end of the switching switch module is connected to the main control module; if the first instruction is received through the coil end of the switching switch module, the first end of the switching switch module is controlled to be connected to the second end of the switching switch module to control the closing of each of the series relays; if the second instruction is received through the coil end of the switching switch module, the first end of the switching switch module is controlled to be connected to the third end of the switching switch to control the closing of each of the parallel relays.

2. The battery charging and discharging circuit according to claim 1, characterized in that: The target data includes: temperature data and voltage data; The main control module is further configured to determine, for each battery cell, that the battery cell is normal if it is confirmed that the temperature data of the battery cell does not exceed a preset temperature threshold and the voltage data of the battery cell is not lower than a preset voltage threshold.

3. The battery charging and discharging circuit according to claim 1, characterized in that: In the module unit, the positive electrode of the first battery module is connected to the total positive terminal of the battery, and the positive electrodes of each battery module other than the first battery module are physically connected to the total positive terminal of the battery through their respective corresponding first relays; The negative electrode of the last battery module is connected to the total negative terminal of the battery, and the negative electrode of each battery module except the last battery module is physically connected to the total negative terminal of the battery through the corresponding second relay.

4. The battery charging and discharging circuit according to claim 3, characterized in that: The plurality of parallel relays includes each of the first relays and each of the second relays.

5. The battery charging and discharging circuit according to claim 1, characterized in that: A series relay is connected between every two adjacent battery modules.

6. The battery charging and discharging circuit according to claim 1, characterized in that: The multiple cells in each battery module are connected in series and / or in parallel according to a preset method.

7. A battery charging and discharging system, characterized in that: The battery charging and discharging circuit comprises the battery charging and discharging circuit according to any one of claims 1 to 6.

8. An electric vehicle, characterized in that: Including the battery charging and discharging system according to claim 7.

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