Battery charging and discharging circuit, battery charging and discharging system and electric vehicle

Abstract

The invention provides a battery charging and discharging circuit, a battery charging and discharging system and an electric automobile, after a control unit determines that each battery cell is normal, if a charging instruction is received and each parallel relay is judged to be non-adhesion, a first instruction is output; the 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 disconnected so as to charge each battery module in series; if the control unit receives the discharge instruction and judges that each series relay is not adhered, a second instruction is output; and 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 disconnected so as to discharge each battery module in parallel. When the circuit is used for charging, a plurality of battery modules can be connected in series, the charging voltage is increased, the charging current is reduced, and the charging speed is improved; and during discharging, a plurality of battery modules can be connected in parallel, and the system voltage is reduced, so that the requirement on the voltage resistance of the whole vehicle can be reduced.

Description

Technical Field

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

[0002] With the advancement of electric vehicle battery technology, in order to solve the problem of slow charging speed of new energy electric vehicles, the relevant technology can increase the charging current to improve the charging speed, but with the increase of charging current, the high-voltage cable used increases exponentially, and the single-gun charging of the national standard charging pile, no matter how high the voltage is, the maximum charging current is 250A; the charging speed can also be increased by increasing the charging voltage, but this method has higher and higher requirements on the insulation performance of the whole vehicle, and the pressure resistance performance of the whole vehicle is also higher and higher. Therefore, in response to the problem of slow charging speed of electric vehicles, there is a lack of effective electric vehicle charging solutions in the relevant technology. Summary of the invention

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

[0004] The present invention provides a battery charging and discharging circuit, the circuit comprising: a control unit, for determining whether each parallel relay in the module unit is stuck if a charging instruction is received, if each battery cell in the module unit is determined to be normal, and outputting a first instruction if there is no sticking; 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 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, for receiving a first instruction, and outputting a series signal according to the first instruction to control each series relay to close, and each parallel relay to disconnect, so as to charge each battery module in series; the control unit, further for determining whether each series relay in the module unit is stuck if a discharge instruction is received, and outputting a second instruction if there is no sticking; the series-parallel switching unit, further for receiving a second instruction, and outputting a parallel signal according to the second instruction to control each parallel relay to close, and each series relay to disconnect, so as to discharge each battery module in parallel.

[0005] Furthermore, the control unit includes: a slave control module, which is used to collect target data of each battery cell in the module unit and send the target data to the main control module; the main control module is used to confirm that each battery cell is normal if the target data of the battery cell are normal; it is also used to determine whether each parallel relay in the module unit is stuck if a charging instruction is received, and output a first instruction if there is no sticking; if a discharging instruction is received, determine whether each series relay in the module unit is stuck, and output a second instruction if there is no sticking.

[0006] Furthermore, the target data includes: temperature data, voltage data; the main control module is also used 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 includes: a power supply having a positive terminal and a negative terminal, the negative terminal being connected to the negative terminal of the coil in each series relay and to the negative terminal of the coil in each parallel relay; a main relay having a first terminal, a second terminal and a coil terminal; the first terminal of the main relay being connected to the positive terminal of the power supply, and the coil terminal of the main relay being connected to the main control module; and being used to close the first terminal and the second terminal of the main relay if a first instruction or a second instruction is received through the coil terminal of the main relay; a switching switch module having a first terminal, a second terminal, a third terminal and a coil terminal; the first terminal of the switching switch module being connected to the second terminal of the main relay, the second terminal of the switching switch module being connected to the positive terminal of the coil of each series relay, the third terminal of the switching switch module being connected to the positive terminal of the coil of each parallel relay, and the coil terminal of the switching switch module being connected to the main control module; and being used to control the first terminal of the switching switch module to be connected to the second terminal of the switching switch module to control each series relay to be closed if a first instruction is received through the coil terminal of the switching switch module; and to control the first terminal of the switching switch module to be connected to the third terminal of the switching switch to control each parallel relay to be closed if a second instruction is received through the coil terminal of the switching switch module.

[0008] Furthermore, 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 electrode of each battery module except the first battery module is physically connected to the total positive terminal of the battery through the corresponding first relay; 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.

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

[0010] Furthermore, a series relay is connected between every two adjacent battery modules.

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

[0012] The present invention provides a battery charging and discharging system, comprising any one of the above-mentioned battery charging and discharging circuits.

[0013] The present invention provides an electric vehicle, comprising the above-mentioned battery charging and discharging system.

[0014] The battery charging and discharging circuit, system and electric vehicle provided by the present invention include: a control unit for determining whether each battery cell in the module unit is normal, if a charging instruction is received, judging whether each parallel relay in the module unit is adhered, and outputting a first instruction if there is no adhesion; wherein the module unit 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, and each battery module includes a plurality of battery cells; the plurality of series relays are used to connect each of the battery modules in series; the plurality of parallel relays are used to connect each of the battery modules in parallel; The series-parallel switching unit is used to receive the first instruction, and output a series signal according to the first instruction to control each of the series relays to close and each of the parallel relays to disconnect, so as to charge each battery module in series; the control unit is also used to determine whether each of the series relays in the module unit is adhered if a discharge instruction is received, and output a second instruction if there is no adhesion; 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 of the parallel relays to close and each of the series relays to disconnect, so as to discharge each of the battery modules in parallel. When charging, the circuit can connect multiple battery modules in series to increase the charging voltage, reduce the charging current, and improve the charging speed; when discharging, multiple battery modules can be connected in parallel to reduce the system voltage, thereby reducing the voltage resistance requirements for the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0018] Figure 3 A schematic diagram of a battery module connected in series according to an embodiment of the present invention;

[0019] Figure 4 A schematic diagram of a battery module connected in parallel provided by an embodiment of the present invention;

[0020] Figure 5 A schematic diagram of a series-parallel switching unit provided by an embodiment of the present invention;

[0021] Figure 6 A schematic diagram of a battery charging and discharging system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the related art, there is a lack of effective electric vehicle charging solutions to address the problem of slow charging speed of electric vehicles. Based on this, an embodiment of the present invention provides 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 understanding of this embodiment, a battery charging and discharging circuit disclosed in an embodiment of the present invention is first introduced. Figure 1 As shown, the circuit includes: a control unit 10 , a series-parallel switching unit 11 and a module unit 12 which are connected in sequence; the control unit 10 is also connected to the module unit 12 .

[0025] The control unit 10 is used to determine whether each parallel relay in the module unit 12 is stuck if a charging instruction is received, when it is determined that each battery cell in the module unit 12 is normal, and output a first instruction if there is no sticking; 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, and each battery module includes a plurality of battery cells; the plurality of series relays are used to connect each battery module in series; and the plurality of parallel relays are used to connect each battery module in parallel;

[0026] The above-mentioned module unit 12 is usually composed of multiple battery modules, and each battery module usually contains multiple battery cells; a battery cell refers to a single electrochemical cell containing positive and negative electrodes, and is the power storage part of the battery module; the above-mentioned charging instruction can be understood as the instruction received by the control unit 10 when the whole vehicle is in a charging preparation state, and the charging instruction is used to indicate that the whole vehicle is in a charging preparation state and needs to be charged; the above-mentioned module unit 12 usually includes multiple parallel relays and multiple series relays. When each parallel relay is closed, each battery module can be connected in parallel, and when each series relay is closed, each battery module can be connected in series; in actual implementation, the control unit 10 starts working after receiving the wake-up power supply of the whole vehicle, and the wake-up power supply can include low voltage electricity and 12V Auxiliary power supply, such as the low-voltage power on the key; after the control unit 10 starts working, it usually first determines whether each battery cell in each battery module is in a normal state, for example, whether there are problems such as overtemperature or low voltage. After confirming that each battery cell is normal, if a charging instruction is received, it is usually necessary to perform adhesion detection on each parallel relay in the module unit 12, specifically, to detect whether the relay contacts of each parallel relay are stuck due to long-term use or overload, that is, the state of contact adhesion; the purpose of adhesion detection is to ensure the safe operation of the circuit and avoid circuit failure or safety hazards caused by adhesion of relay contacts; when the control unit 10 confirms that each parallel relay is not adhered, it can output a first instruction and send the first instruction to the series-parallel switching unit 11.

[0027] A series-parallel switching unit 11 is used to receive a 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;

[0028] In actual implementation, when the series-parallel switching unit 11 receives the above-mentioned first instruction, it can output a series signal and send the series signal to the module unit 12, so that each series relay in the module unit 12 is closed, and at the same time, each parallel relay is disconnected; after each series relay is closed, each battery module can be connected in series, so that each battery module can be charged in series.

[0029] The control unit 10 is further configured to, if a discharge instruction is received, determine whether each series relay in the module unit 12 is adhered, and if not, output a second instruction;

[0030] After confirming that each battery cell is normal, if the control unit 10 receives a discharge command, it is usually necessary to perform a sticking test on each series relay in the module unit 12, specifically, to detect whether the relay contacts of each series relay are 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 command and send the second command to the series-parallel switching unit 11.

[0031] The series-parallel switching unit 11 is also used to receive a 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.

[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 at the same time, each series relay is disconnected; after each parallel relay is closed, each battery module can be connected in parallel, so as to realize parallel discharge of each battery module.

[0033] The battery charging and discharging circuit can connect multiple battery modules in series during charging to increase the charging voltage, reduce the charging current, and improve the charging speed; during discharging, multiple battery modules can be connected in parallel to reduce the system voltage, thereby reducing the voltage resistance requirements for the entire vehicle.

[0034] Furthermore, the control unit includes: a slave control module and a master control module; the 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 master control module is used to confirm that each battery cell is normal if the target data of the battery cell are normal; it is also used to determine whether each parallel relay in the module unit is stuck if a charging instruction is received, and output a first instruction if there is no sticking; if a discharging instruction is received, determine whether each series relay in the module unit is stuck, and output a second instruction if there is no sticking.

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

[0036] Furthermore, the target data includes: temperature data, voltage data; the main control module is also used 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.

[0037] The above-mentioned preset temperature threshold and preset voltage threshold can be set according to actual needs; in actual implementation, the slave control module can collect the temperature data and voltage data of each battery cell and upload them to the main control module. The main control module can determine for each battery cell whether the temperature data of the battery cell exceeds the preset temperature threshold. If it exceeds the preset temperature threshold, it is generally considered that the temperature of the battery cell is too high and there is a risk of combustion and fire; 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 this battery cell is 2V, that is, the voltage data of the battery cell is too low. When the temperature data and / or voltage data of a battery cell are abnormal, the battery cell is generally considered to be abnormal. Only when the temperature data and voltage data of the battery cell are normal, the battery cell is considered to be normal.

[0038] Furthermore, the series-parallel switching unit includes: a power supply, a main relay and a switching switch module; wherein the power supply has a positive terminal and a negative terminal, the negative terminal is connected to the negative terminal of the coil in each series relay, and is connected to the negative terminal of the coil in each parallel relay; the voltage value of the power supply can be set according to actual needs, for example, a 24V power supply can be selected; the negative terminal of the power supply is connected to the negative terminal of the coil in each series relay in the module unit, and is also connected to the negative terminal of the coil in each parallel relay.

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

[0040] A switching switch module comprises 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 series relay, the third end of the switching switch module is connected to the positive end of the coil of each parallel relay, and the coil end of the switching switch module is connected to the main control module; if a 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 each series relay to be closed; if a 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 each parallel relay to be closed.

[0041] The above-mentioned 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 positive end and a negative end of the coil, and the positive end and the negative end of the coil are connected to the main control module. The first instruction and the second instruction issued by the main control module can be sent to the positive end and the negative end of the coil. In specific implementation, when the positive end and the negative end of the coil 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 positive end of the coil of each series relay, the power supply can power the coil in each series relay, so that current flows through the coil, so that each series relay is attracted, and then each battery module can be charged in series. When the positive end and the negative end of the coil 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 positive end of the coil of each parallel relay, the power supply can power the coil in each parallel relay, so that current flows through the coil, thereby closing each parallel relay, and then each battery module can be discharged in parallel.

[0042] Furthermore, 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 electrode of each battery module except the first battery module is physically connected to the total positive terminal of the battery through the corresponding first relay; 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; the parallel relay includes each first relay and each second relay.

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

[0044] Furthermore, a series relay is connected between every two adjacent 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, and 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. When each series relay is energized, multiple battery modules can be connected in series.

[0045] Furthermore, the multiple battery cells in each battery module are connected in series and / or in parallel in a preset manner; the preset manner can be set according to actual needs, for example, the form of x parallel and y series can be adopted, wherein the values ​​of x and y can be set according to actual needs and are not limited here; the number of battery cells and the battery cell connection method in each battery module are usually the same.

[0046] For easier understanding, see Figure 2 A schematic diagram of a module unit is shown, and the module unit takes a module including four battery modules as an example to illustrate the method of performing adhesion detection on the relay, such as Figure 2As shown, when all relays are disconnected, if the voltage that matches battery module 1 is detected between points A and F, it is confirmed that the K1 relay is stuck; otherwise, the K1 relay is normal. If the voltage that matches battery module 2 is detected between points B and F, it is confirmed that the K2 relay is stuck; otherwise, the K2 relay is normal. If the voltage that matches battery module 3 is detected between points C and F, it is confirmed that the K3 relay is stuck; otherwise, the K3 relay is normal. If the voltage that matches battery module 1 is detected between points B and E, it is confirmed that the P1 relay is stuck; otherwise, the P1 relay is normal. If the voltage that matches battery module 1 is detected between points C and E, the P2 relay is stuck; otherwise, the P2 relay is normal. If the voltage that matches battery module 1 is detected between points D and E, it is confirmed that the P3 relay is stuck; otherwise, the P3 relay is normal. If the voltage that matches battery module 1 is detected between points A and B, it is confirmed that the X1 relay is stuck; otherwise, the X1 relay is normal. If the voltage that matches battery module 2 is detected between points B and C, it is confirmed that the X2 relay is stuck; otherwise, the X2 relay is normal. If the voltage that matches the battery module 3 is detected between points C and D, it is confirmed that the X3 relay is sticky; otherwise, the X3 relay is normal. Figure 2 In the embodiment, the cells in the battery module 1, the battery module 2, the battery module 3 and the battery module 4 can all be arranged in an x-parallel and y-series manner.

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

[0048] See also Figure 3 A schematic diagram of a battery module connected in series is shown, combined with Figure 2 In this state, the X1 relay, X2 relay, and X3 relay are all closed, and the K1 relay, K2 relay, K3 relay, P1 relay, P2 relay, and P3 relay must all be disconnected. The series-parallel state of the entire system is x parallel 4y series.

[0049] See also Figure 4 A schematic diagram of a battery module connected in parallel is shown, combined with Figure 2 In this state, the X1 relay, X2 relay, and X3 relay are all disconnected, and the K1 relay, K2 relay, K3 relay, P1 relay, P2 relay, and P3 relay must all be closed. The series-parallel state of the entire system is 4x parallel and y series.

[0050] In the entire system, the series relay and the parallel relay are not allowed to be closed at the same time under any circumstances. Once they are closed at the same time, the battery module will short-circuit, destroying the entire battery or even the vehicle. Therefore, to ensure safety, the following are provided: Figure 5 The schematic diagram of a series-parallel switching unit is shown, that is, adding a series relay and a parallel relay to the control circuit Figure 5 In the circuit shown, when the parallel relay needs to be closed, the main control module closes the K relay; when the series relay needs to be closed, the main control module closes the K relay and the X relay. In the entire system, no matter whether the K relay and the X relay are in the closed or open state, the parallel relay and the series relay will not be closed at the same time.

[0051] Specifically, when discharging, the vehicle sends the discharge status to the main control module through communication. The main control module first completes the adhesion detection of the relevant relays. When it is confirmed that there is no adhesion, the K relay is closed, and then the parallel relay is closed. When charging, after the main control module detects the charging pile connection signal, the main control module first completes the adhesion detection of the relevant relays. When it is confirmed that there is no adhesion, the K relay and the X relay are closed, and then the series relay is closed.

[0052] The battery charging and discharging circuit controls the relays during charging to change the state of multiple battery modules to series connection, thereby increasing the battery voltage and reducing the charging current. When discharging, the relays are controlled to change the state of the battery modules to parallel connection, thereby reducing the discharge voltage.

[0053] An embodiment of the present invention provides a battery charging and discharging system, comprising any one of the above-mentioned battery charging and discharging circuits.

[0054] See also Figure 6 The schematic diagram of a battery charging and discharging system is shown in FIG. The entire system working process is as follows:

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

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

[0057] 3. The main control module determines whether the battery cell has a combustion problem by whether the temperature data is too high, and determines whether the battery cell is abnormal by whether the voltage data is too low (for example, the voltage of most battery cells is 3.2V, but the voltage of some battery cells is 2.0V).

[0058] 4. If there is no abnormality in the battery cell, the main control module performs relay adhesion detection based on the voltage data of the battery cell. The main control module accumulates the battery cell data of 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 current module voltage, the corresponding relay is judged to be adhered.

[0059] 5. If the main control module receives that the vehicle is in a discharging state, the main control module only needs to determine whether the X1 relay, X2 relay, and X3 relay are adhered. If there is no adhesion, the main control module closes the K relay.

[0060] 6. If the main control module receives that the vehicle is in charging state, the main control module only needs to determine whether the K1 relay, K2 relay, K3 relay, P1 relay, P2 relay, and P3 relay are adhered. If there is no adhesion, the main control module closes the K relay and the X relay.

[0061] The above battery charging and discharging system, when charging, can change the connection state of the battery module, connect multiple battery modules in series, increase the charging voltage, improve the system voltage, reduce the charging current, and separate the charging circuit, so that it can meet the normal use of the whole vehicle and improve the charging speed. At the same time, it only needs to increase the insulation performance of the charging part. In the case of discharge, multiple battery modules are connected in parallel to reduce the system voltage and the withstand voltage requirements of other components of the whole vehicle. This system is more suitable for charging piles on the existing market.

[0062] At present, the voltage platform of vehicles on the market is generally 500V, while the voltage output of charging piles can reach 1000V, but the maximum output current is limited to 250A. The system can effectively use the power of charging piles and increase the charging speed of vehicles by adjusting the series and parallel connection of battery modules to change the battery state.

[0063] An embodiment of the present invention provides an electric vehicle, comprising the above-mentioned 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 present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery charging and discharging circuit, characterized in that: The circuit comprises: A control unit, for determining whether each battery cell in the module unit is normal, if a charging instruction is received, to determine whether each parallel relay in the module unit is adhered, and if not, to output a first instruction; wherein the module unit 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, and each battery module includes a plurality of battery cells; the plurality of series relays are used to connect each of the battery modules in series; the plurality of parallel relays are used to connect each of the battery modules in parallel; A series-parallel switching unit, configured to receive the first instruction, and output a series connection signal according to the first instruction to control each of the series connection relays to be closed and each of the parallel connection 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 adhered, 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 of the parallel relays to close and each of the series relays to open, so as to discharge each of the battery modules in parallel.

2. The battery charging and discharging circuit according to claim 1, characterized in that: The control unit comprises: A slave control module, used for collecting target data of each battery cell in the module unit, and sending the target data to the master control module; The main control module is used to confirm that each battery cell is normal if the target data of the battery cell are all normal; it is also used to determine whether each parallel relay in the module unit is stuck if a charging instruction is received, and output a first instruction if there is no sticking; if a discharging instruction is received, determine whether each series relay in the module unit is stuck, and output a second instruction if there is no sticking.

3. The battery charging and discharging circuit according to claim 2, characterized in that: The target data includes: temperature data and voltage data; The main control module is also used 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.

4. The battery charging and discharging circuit according to claim 2, characterized in that: The series-parallel switching unit comprises: 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 is connected to the positive end of the power supply, and the coil end of the main relay is connected to the main control module; and is used 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 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 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 each of the series relays to be closed; 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 each of the parallel relays to be closed.

5. 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 except 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.

6. The battery charging and discharging circuit according to claim 5, characterized in that: The plurality of parallel relays includes each of the first relays and each of the second relays.

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

8. 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 in a preset manner.

9. A battery charging and discharging system, characterized in that: A battery charging and discharging circuit comprising the battery charging and discharging circuit according to any one of claims 1 to 8.

10. An electric vehicle, characterized in that: A battery charging and discharging system comprising the battery charging and discharging system as claimed in claim 9.

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