Battery management system with same charging and discharging port and storage battery power supply

Abstract

The invention provides a battery management system with the same charging and discharging port. The battery management system comprises a front-end sampling protection unit, a monitoring communication unit, a storage battery charging and discharging loop, a battery side power supply loop and a charging and discharging port side power supply loop, wherein the battery side power supply loop and the charging and discharging port side power supply loop supply power to the front-end sampling protection unit and the monitoring communication unit. According to the technical scheme, two power supply loops of the battery side and the charging and discharging port side are provided, the single battery under-voltage protection function and the pack end under-voltage protection function can be achieved, power supply to the battery of the BMS can be automatically cut off when the single battery is under-voltage, power consumption of the battery pack is reduced, and the service life of the storage battery is prolonged.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power supply, and in particular to a battery management system and a battery power supply with simultaneous charging and discharging ports. Background Art

[0002] In industrial production, in order to improve the power supply reliability of important electrical equipment, a rechargeable battery pack composed of multiple rechargeable secondary batteries (hereinafter referred to as a battery pack) is often used as a backup AC or DC power supply (hereinafter referred to as a backup power supply) for power supply. For example, in a coal mine environment, various flameproof and intrinsically safe battery power supplies, encapsulated and intrinsically safe DC regulated power supplies, etc. are used as backup power supplies.

[0003] In order to ensure efficient, safe and reliable operation of the battery pack, the battery pack is usually equipped with a battery management system BMS (Battery Management System) to monitor and manage the performance of the battery. Small and medium-capacity battery packs are usually sold as a group of multiple single cells with BMS installed, also known as "battery packs"; large-capacity battery packs are usually sold as single cells, and BMS is installed separately when used. BMS consumes the power of the battery pack when working. BMS manages the charge and discharge of the battery pack through the charge and discharge interface, which has two designs: the same charge and discharge port and the separate charge and discharge port.

[0004] For a BMS with the same charging and discharging port, whether it is a small or medium-sized battery pack during storage, transportation, and before commissioning, or a large or small-capacity battery pack in a static or discharging mode in a backup power supply, there is a risk of over-discharging the battery and damaging the single cell due to the BMS's prolonged power consumption, or there is a risk of the BMS undervoltage protection being activated due to the single cell voltage being too low, making it impossible to activate the battery pack for charging. Summary of the invention

[0005] The invention provides a battery management system with a charging and discharging port, which is used to solve the problems of insufficient undervoltage protection capability and inability to activate charging of existing storage batteries with a charging and discharging port.

[0006] To solve the above technical problems, the present invention is achieved as follows:

[0007] In one aspect, the present invention provides a battery management system with a charging and discharging port, comprising:

[0008] A front-end sampling and protection unit, a monitoring and communication unit, a battery charging and discharging circuit, and a battery-side power supply circuit and a charging and discharging port-side power supply circuit for supplying power to the front-end sampling and protection unit and the monitoring and communication unit;

[0009] The battery-side power supply circuit is provided with a power switch K1, and draws power from the battery pack;

[0010] The front-end sampling protection unit is used to collect the single cell undervoltage signal of the battery pack, and the monitoring communication unit is used to control the power switch K1 to disconnect according to the single cell undervoltage signal, so as to close the battery side power supply circuit;

[0011] A charging and discharging port power supply unit is provided in the power supply circuit on the charging and discharging port side, the input end of the charging and discharging port power supply unit is connected to the battery charging and discharging circuit, and the output end supplies power to the front-end sampling protection unit and the monitoring communication unit; the charging and discharging port power supply unit turns off the charging port power supply when the battery group end is undervoltage or the single cell is undervoltage, and turns on the power supply after the charging voltage is applied to the charging and discharging port to activate the battery charging and discharging circuit.

[0012] On the other hand, the present invention provides a battery power supply with a charging and discharging port, the power supply comprising: a battery pack and the aforementioned battery management system.

[0013] The technical solution of the present invention has the following beneficial effects:

[0014] (1) It has two power supply circuits on the battery side and the charging and discharging port side, which can realize the single cell undervoltage protection and group end undervoltage protection functions. When the single cell is undervoltage, it can automatically cut off the battery power supply to the BMS, reduce the power consumption of the battery pack, and extend the battery life;

[0015] (2) When the single cell is under voltage protection, charging at the charging and discharging port can supply power to the BMS through the power supply circuit on the charging and discharging port side, activating the charging circuit of the battery pack to prevent the battery from falling into a state where it cannot be charged;

[0016] (3) The power supply circuit on the charging port side uses an electronic circuit to realize the cut-off function, which has a simple structure and stable performance. The circuit elements used will not increase the hardware cost significantly. The added circuit itself consumes only a very small amount of electricity and will not increase the additional consumption burden of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a battery management system with a charging and discharging port provided in an embodiment of the present disclosure;

[0019] Figure 2 A schematic diagram of the structure of a battery management system with a charging and discharging port provided in another embodiment of the present disclosure;

[0020] Figure 3 4 is a circuit diagram of a charging port power supply unit in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present disclosure. In addition, for the sake of clarity, parts that are not related to the description of the exemplary embodiments are omitted in the drawings.

[0022] In this specification, it should be understood that terms such as "including" or "having" are intended to indicate the existence of the features, numbers, steps, behaviors, components, parts or combinations thereof disclosed in the present disclosure, and are not intended to exclude the possibility that one or more other features, numbers, steps, behaviors, components, parts or combinations thereof exist or are added. It should also be noted that the embodiments in the present disclosure and the features in the embodiments may be combined with each other if there is no conflict.

[0023] For BMS with the same charging and discharging port design, although BMS adopts a low-power design, the long-term accumulation of power consumption during the operation of BMS will also bring risks to the battery. For small and medium-capacity battery packs, even if it is not installed as a backup power supply, BMS will consume the power of the battery pack during storage and transportation. After being installed as a backup power supply, BMS will also consume the power of the battery pack when it is in a static and discharging state during storage, transportation, and commissioning. For large-capacity battery packs, after BMS is installed and used as a backup power supply, BMS will also consume the power of the battery pack when it is in a static and discharging state during storage, transportation, and commissioning. Long-term power consumption of BMS may cause over-discharge of the battery, damage the single cell, or cause the BMS undervoltage protection to be activated due to the low voltage of the single cell, disconnecting the charging circuit of the battery, resulting in the inability to activate charging of the battery pack.

[0024] Based on this, the present disclosure provides a battery management system with a charging and discharging port, which can realize undervoltage protection for single cells and low voltage protection for the battery pack end, and can automatically activate the charging circuit of the battery during pressurized charging.

[0025] Figure 1 A schematic diagram of the structure of a battery management system with a charging and discharging port provided in an embodiment of the present disclosure.

[0026] like Figure 1As shown, the battery management system includes a front-end sampling and protection unit 110, a monitoring and communication unit 120, a battery charging and discharging circuit, and a battery-side power supply circuit and a charging and discharging port-side power supply circuit for powering the front-end sampling and protection unit 110 and the monitoring and communication unit 120.

[0027] A power switch K1 is provided in the battery side power supply circuit to draw power from the battery pack.

[0028] The front-end sampling protection unit 110 is used to collect the single cell undervoltage signal of the battery pack, and the monitoring communication unit 120 is used to control the power switch K1 to disconnect according to the single cell undervoltage signal to close the battery side power supply circuit.

[0029] A charging and discharging port power supply unit 140 is provided in the power supply circuit on the charging and discharging port side. The input end of the charging and discharging port power supply unit 140 is connected to the battery charging and discharging circuit, and the output end supplies power to the front-end sampling protection unit 110 and the monitoring communication unit 120. The charging and discharging port power supply unit 140 turns off the charging and discharging port power supply when the battery group end is undervoltage or the single cell is undervoltage, and turns on the power supply after the charging voltage is applied to the charging and discharging port to activate the battery charging and discharging circuit.

[0030] Figure 1 In the battery side power supply circuit, a current limiting and voltage dropping resistor Rd and an anti-reverse diode D1 are also provided. From the B+ of the battery to the diode D1 is the positive end line of the battery side power supply circuit. The positive end of the power input of the front-end sampling protection unit 110 and the monitoring and communication unit 120 are connected to the positive pole of the battery through D1, K1 and Rd in sequence, that is, the VB end of the front-end protection unit 110 and the Vm end of the monitoring and communication unit 120 are connected to the B+ of the battery.

[0031] The battery charging and discharging circuit is Figure 1 The circuit from the charging and discharging ports P+ and P- to the battery terminals B+ and B-. Figure 1 As shown, a sampling resistor Rs and a charge-discharge control switch KM are provided in the battery charge-discharge circuit. The control end of the charge-discharge control switch KM is connected to the Kz port of the front-end sampling protection unit 110, and is disconnected when the front-end sampling protection unit loses power. Figure 1 As shown in the figure, the charge and discharge control switch KM is set in the circuit connecting the negative electrode of the battery pack. This is a low-end control mode BMS. There is also a high-end control mode BMS, that is, the charge and discharge control switch KM is set in the circuit connecting the positive electrode of the battery pack, such as Figure 2 shown.

[0032] like Figure 1As shown, an anti-reverse diode D2 is provided in the power supply circuit on the charging and discharging port side, and the charging and discharging port power supply unit includes an undervoltage protection circuit 141 and an isolated DC / DC module 142. The input end of the undervoltage protection circuit 141 is connected to the charging and discharging ports P+ and P-, and the output end is connected to the enable end of the isolated DC / DC module 142. When the enable end is valid, the isolated DC / DC module 142 converts the power supply voltage input from the charging and discharging ports (P+, P-) or the battery pack end (B+, B-) into an output voltage, and supplies power to the front-end sampling protection unit 110 and the monitoring communication unit 120 through the anti-reverse diode D2.

[0033] like Figure 1 As shown, the monitoring communication unit 120 further includes a DC / DC module 121 and an MCU control unit 122. The DC / DC module 121 converts the input power supply voltage into the working voltage of the MCU control unit 122. The MCU control unit 122 receives the single cell undervoltage signal provided by the front-end sampling protection unit 110, and controls the power switch K1 on and off through the control signal terminal Kq.

[0034] Furthermore, the battery management system also includes a communication interface unit 130. The communication interface unit 130 is powered by the DC / DC module 121 and connected to the communication port Sw of the MCU control unit 122. The communication interface unit is used to realize the communication connection between the BMS and the outside world, such as remote monitoring of the working status of the battery.

[0035] Figure 2 A schematic diagram of the structure of a battery management system with a charging and discharging port provided in another embodiment of the present disclosure.

[0036] exist Figure 2 The charge and discharge control switch KM is set at the positive electrode of the battery pack, which is also called high-end control mode. Figure 1 In the above method, the charge and discharge control switch KM is set at the negative electrode of the battery pack, which is also called the low-end control method. Both of these control methods of BMS can achieve the purpose of the present invention. Since the specific working principles are the same, the following will be Figure 1 The low-end control scheme in is used as an example to illustrate.

[0037] First of all Figure 1 The specific connection method of each module in is described below.

[0038] (1) Front-end sampling protection unit

[0039] The front-end sampling protection unit 110 is generally composed of a single front-end protection chip 111 and a number of discrete resistors and capacitors. It has a number of single-cell voltage collection terminals B0, B1-...Bn, which are respectively connected to the B+, B- terminals of the battery pack BAT and the common terminals of each single cell, and are used to collect single-cell voltages and the group terminal voltage of the battery pack. The power ground GND of the front-end sampling protection unit 110 is connected to the ground B- of the battery pack, and the power positive VB of the front-end sampling protection unit 110 is connected to the common terminal of the battery side power supply anti-reverse diode D1 and the charge and discharge port side power supply anti-reverse diode D2. The front-end sampling protection unit 110 can obtain power from the battery side and the charge and discharge port side through diodes D1 and D2, and the end with higher voltage is powered.

[0040] The group-end current acquisition terminals Is+ and Is- of the front-end sampling protection unit 110 are respectively connected to the two ends of the charge and discharge current sampling resistor Rs to collect the charge and discharge current signals of the battery pack; the charge and discharge control signal terminal Kz is connected to the control end of the charge and discharge control switch KM to control the charging and discharging of the battery pack.

[0041] The communication port Sq of the front-end sampling protection unit 110 is connected to the communication port Sm of the monitoring communication unit 120. The monitoring communication unit 120 obtains the sampling information and protection status of the front-end sampling protection unit 110 through this communication interface, and initializes various parameters and protection constants for it, and controls its sleep and operation modes.

[0042] (2) Monitoring communication unit

[0043] The monitoring communication unit 120 is composed of a DC / DC module 121 and an MCU control unit 122. The power input terminals Vm and GND of the DC / DC module 121 are respectively connected to the power supply terminals VB and GND of the front-end sampling protection unit 110, and the voltage output terminal Vt of the DC / DC module 121 is connected to the power supply terminal EN of the MCU control unit 122. The DC / DC module 121 and the front-end sampling protection unit 110 share a power supply, and the DC / DC module 121 converts the common power supply voltage into a low voltage (generally 5V, 3.3V or 1.8V) to power the MCU control unit 122.

[0044] The control signal terminal Kq of the monitoring communication unit 120 is connected to the control terminal of the battery side power supply switch K1, and the communication port Sm is connected to the communication port Sq of the front-end sampling protection unit 110. After receiving the single cell undervoltage signal from the front-end sampling protection unit 110, the monitoring communication unit 120 controls the battery side power supply switch K1 to disconnect the battery side power supply. Conversely, when the battery undervoltage fault disappears, the battery side power supply is restored.

[0045] (3) Communication interface

[0046] The power supply end of the communication interface 130 is connected to the output of the DC / DC module 121 and is powered by the DC / DC module 121. The signal input end of the communication interface 130 is connected to the communication port Sw of the MCU control unit 122 to realize the external communication function.

[0047] (4) Charging and discharging port power supply unit

[0048] The charging and discharging port power supply unit 140 is composed of an undervoltage protection circuit 141 and an isolated DC / DC module 142. The input end of the undervoltage protection circuit 141 is respectively connected to the positive end P+ and the negative end P- of the charging and discharging port, and the comparison output signal Vt is connected to the enable end of the isolated DC / DC module 142.

[0049] The power input end of the isolated DC / DC module 142 is respectively connected to the positive end P+ and the negative end P- of the charging and discharging port, and the voltage output end is connected to the positive electrode of the anti-reverse diode D2 on the charging and discharging port side.

[0050] When the voltage of the charge and discharge port is greater than the set value, the Vt terminal of the undervoltage protection circuit 141 outputs an enable signal to control the output voltage of the isolated DC / DC module 142, and the voltage passes through the anti-reverse diode D2 to provide a second power supply for the front-end sampling protection unit 110 and the monitoring communication unit 120. On the contrary, if the voltage of the charge and discharge port is lower than the set value, the Vt terminal of the undervoltage protection circuit 141 outputs a disable signal to turn off the output voltage of the isolated DC / DC module 142, that is, turn off the power supply of the charge and discharge port to the front-end sampling protection unit 110 and the monitoring communication unit 120.

[0051] (5) Others

[0052] The first end of the current limiting and voltage dropping resistor Rd is connected to B+, and the second end is connected to a contact of the battery side power supply switch K1. Another contact of the power supply switch K1 is connected to the anode of the anti-reverse diode D1, and the cathode of the diode D1 is connected to the positive power supply terminals VB and Vm of the front-end sampling protection unit 110 and the monitoring communication unit 120.

[0053] The control end of the power switch K1 is connected to the control signal output end Kq of the MCU control unit 122. When the voltage of each single cell in the battery is normal, the control signal output end Kq of the MCU control unit 122 outputs an enable signal to control the battery-side power switch K1 to be turned on, so as to realize the power supply from the battery side to the front-end sampling protection unit 110 and the monitoring communication unit 120. On the contrary, when a single cell in the battery pack is undervoltage, the control signal output end Kq of the MCU control unit 122 outputs a disable signal to control the battery-side power switch K1 to be turned off, so as to turn off the power supply from the battery side to the front-end sampling protection unit 110 and the monitoring communication unit 120.

[0054] The working principle and control points of the battery management system in the embodiment of the present disclosure are described below.

[0055] The single cell undervoltage protection value of the front-end sampling protection unit 110 is set to Vl. For example, V1 of a lithium iron phosphate battery can be set to 2.75V. The group terminal voltage protection value Vdl of the undervoltage protection circuit 141 is set to n*(Vl+0.075V), where n is the number of battery groups. For example, Vd1 of a lithium iron phosphate battery can be set to n*(2.75V+0.075V).

[0056] (1) When the battery pack is in a stationary state or is used as a backup power source and the mains voltage is lost

[0057] (1.1) Situation 1: Battery voltage is normal

[0058] When the battery pack voltage is normal, the voltage of each single cell is generally higher than the single cell voltage undervoltage protection value Vl, and the group terminal voltage is generally higher than the undervoltage protection value Vdl.

[0059] At this time, since the group terminal voltage is greater than the undervoltage protection value, the undervoltage protection circuit 141 outputs an enable signal to isolate the DC / DC module 142 output voltage; the front-end sampling protection unit 110 cannot detect the single cell undervoltage information, and the MCU control unit 122 cannot receive the single cell undervoltage information, so the MCU outputs an enable signal to control the battery side power supply switch K1 to turn on. Both the battery side and the charging and discharging port side power supply circuits can supply power to the front-end sampling protection unit 110 and the monitoring communication unit 120. According to the circuit structure of D1 and D2, the diode on the side with a higher voltage is turned on to supply power.

[0060] Therefore, the BMS is in normal working condition, the charge and discharge control switch KM is in a closed state, and if the mains voltage is lost, the battery pack can be discharged normally.

[0061] (1.2) Situation 2: Low voltage at the battery group terminal and normal voltage at the single cell

[0062] In this case, the voltage of each single cell is higher than the single cell voltage undervoltage protection value Vl, and the group terminal voltage is lower than the undervoltage protection value Vdl, which is also called battery group terminal undervoltage.

[0063] At this time, since the group terminal voltage is lower than the undervoltage protection value, the undervoltage protection circuit 141 outputs a disable signal to turn off the output voltage of the isolated DC / DC module 142; the front-end sampling protection unit 110 cannot detect the undervoltage information of the single cell, and the MCU control unit 122 cannot receive the undervoltage information of the single cell, so the MCU outputs an enable signal to control the battery side power supply switch K1 to turn on. Therefore, only the battery side (B+, B- ends) supplies power to the front-end sampling protection unit 110 and the monitoring communication unit 120, and the charging and discharging port side (P+, P- ends) does not supply power.

[0064] Therefore, the BMS is in normal working condition, the charge and discharge control switch KM is in a closed state, and if the mains voltage is lost, the battery pack can be discharged normally.

[0065] (1.3) Scenario 3: Undervoltage of single battery in battery pack

[0066] In this case, the voltage of more than one single battery is lower than the single battery voltage undervoltage protection value Vl, and the group terminal voltage is lower than the undervoltage protection value Vdl.

[0067] At this time, since the group terminal voltage is lower than the undervoltage protection value, the undervoltage protection circuit 141 outputs a disabling signal to shut down the output voltage of the isolated DC / DC module 142; the front-end sampling protection unit 110 detects the undervoltage information of the single cell, and the MCU control unit 122 receives the undervoltage information of the single cell, so the MCU outputs a disabling signal to disconnect the battery side power supply switch K1. Both the battery side and the charging and discharging port side cannot be powered.

[0068] Therefore, both power supply circuits of the BMS are disconnected and cannot work normally, and the charge and discharge control switch KM is in the disconnected state.

[0069] (2) When the battery is used as a backup power source and the mains power is on

[0070] (2.1) Situation 1: Battery voltage is normal

[0071] Under normal circumstances, the voltage of each single cell of the battery pack is generally higher than the single cell undervoltage protection value Vl, and the group terminal voltage is generally higher than Vdl.

[0072] Since the charge and discharge control switch KM is in the closed state, the battery charge and discharge circuit is connected. If the battery pack is low on power, the charging circuit can charge normally, and if the mains voltage is lost, the battery pack can discharge normally.

[0073] (2.2) Scenario 2: Battery terminal voltage is low

[0074] Under normal circumstances, the voltage of each single cell of the battery pack is generally higher than the single cell undervoltage protection value Vl, and the group terminal voltage is lower than Vdl.

[0075] Since the charge and discharge control switch KM is in the closed state, the battery charge and discharge circuit is connected. If the battery pack is low on power, the charging circuit can charge normally, and if the mains voltage is lost, the battery pack can discharge normally.

[0076] (2.3) Scenario 3: Undervoltage of single battery in battery pack

[0077] In this case, the voltage of more than one single battery is lower than the single battery undervoltage protection value Vl, and the group terminal voltage is lower than Vdl.

[0078] Since the charge and discharge control switch KM is in the off state after the single cell undervoltage protection, the battery charge and discharge circuit is disconnected. When the charging voltage is applied to the charge and discharge ports (P+, P- ends), the port voltage rises back to greater than Vdl, the undervoltage protection circuit 141 outputs an enable signal, the isolated DC / DC module 142 outputs the voltage, the charge and discharge port side power supply circuit is connected, and the BMS can obtain power supply. When the BMS is powered on and works normally, the MCU control unit 122 is powered on and reset, the front-end protection chip 111 is initialized, the charge and discharge control switch KM is controlled to close, and the battery charge and discharge circuit is connected to charge the battery pack.

[0079] After charging, the voltage of each single cell of the battery pack rises, the single cell undervoltage fault is eliminated, and the front-end sampling protection unit 110 controls the battery side power supply switch K1 to turn on, so that both power supply circuits of the BMS are connected and the normal working state is restored.

[0080] According to the above working principle, the purpose of designing the charging and discharging side power supply circuit in the embodiment of the present disclosure is mainly to prevent the battery pack from being unable to charge.

[0081] Specifically, when a single cell in the battery pack is under-voltage, the front-end sampling protection unit 110 detects the single cell under-voltage information, and the MCU control unit 122 receives the single cell under-voltage information and outputs a disable signal to control the battery side power supply switch K1 to disconnect. The front-end sampling protection unit 110 thus loses power supply and cannot work normally and outputs an enable signal. The charge and discharge control switch KM is disconnected due to the loss of the enable signal, causing the BMS to completely lose power supply and stop working.

[0082] At this time, if there is no power supply circuit on the charging and discharging side, when the charging voltage is applied, the battery charging and discharging circuit of the BMS cannot be connected due to the disconnection of the charging and discharging control switch KM, and the BMS cannot obtain power and resume normal operation, causing the charging and discharging control switch KM to be in the disconnected state all the time, and the charging and discharging circuit cannot charge the battery pack. The battery pack enters a "zombie" state and cannot be released by itself.

[0083] When the charging port side power supply circuit provided by the embodiment of the present disclosure is added, the charging port side power supply circuit can obtain electric energy from the charging port to power the BMS. After the BMS is powered on and works normally, the MCU is powered on and reset, and the charge and discharge control switch KM is controlled to be closed, and the battery charge and discharge circuit is connected, so that the battery pack can be charged and work normally.

[0084] In the embodiment of the present disclosure, the charging and discharging port power supply unit 140 uses an isolation DC / DC module 142 to isolate the B- of the battery and the P- of the charging and discharging port, so that the charging and discharging control switch KM can disconnect the charging port. If a non-isolated DC / DC module is used, the B- of the battery pack and the P- of the charging and discharging port cannot be separated, and the charging and discharging control switch KM cannot disconnect the charging port.

[0085] The setting of the group terminal voltage protection value Vdl of the undervoltage protection circuit 141 is analyzed below.

[0086] In general, Vd1 should be slightly higher than n*Vl, and can be set to n*(Vl+0.075V). For example, for lithium iron phosphate batteries, Vd1 can generally be set to n*(2.75V+0.075V). This can ensure that the undervoltage protection circuit 141 generates a protection signal before the front-end sampling protection unit 110 and disconnects the charging and discharging side power supply circuit of the BMS, and eliminates protection failure caused by differences in component parameter accuracy during mass production of products.

[0087] The reason for adopting such a setting of the group terminal voltage protection value is that, when the battery pack is at rest or discharging, it is necessary to ensure that the undervoltage protection circuit 141 generates a protection signal before the front-end sampling protection unit 110 and disconnects the charging and discharging side power supply circuit, so that when the single cell voltage protection action occurs and the battery side cuts off the power supply to the BMS, both power supplies of the BMS are turned off, the BMS stops working, and the charging and discharging control switch KM is disconnected, and the battery stops discharging to the outside to achieve the purpose of protecting the battery. Otherwise, even if the front-end sampling protection unit 110 has a single cell voltage undervoltage protection action and cuts off the power supply on the battery side, the charging and discharging port power supply unit 140 still has an input voltage through the charging and discharging control switch KM, if the group terminal undervoltage protection value Vdl is set lower than n*Vl, the group terminal voltage of the battery will be higher than Vdl at this time, the charging and discharging port power supply unit 140 is still in a normal power supply state, and the BMS can still be powered by the charging and discharging port power supply unit 140, and the charging and discharging control switch KM will not be disconnected, and the over-discharging protection of the battery pack cannot be achieved.

[0088] On the other hand, the Vdl setting value cannot be too high. Otherwise, when the mains power is on, if the charging voltage is lower than Vdl, the undervoltage protection circuit 141 will be in a protection state all the time, and the front-end sampling protection unit 110 and the monitoring communication unit 120 cannot be powered, so the charging function cannot be activated.

[0089] Therefore, the setting of Vd1 should be slightly higher than n times the single cell voltage protection setting value V1, preferably n*(Vl+0.075V), and less than n*(Vl+0.25V), where n is the number of battery groups and V1 is the undervoltage protection value of the single cell.

[0090] In combination with the chip and component selection, a specific embodiment of the present disclosure is given below. The battery pack in this embodiment is a 6-string lithium iron phosphate battery pack.

[0091] Figure 3 1 is a circuit schematic diagram of a charging and discharging port power supply unit in an embodiment of the present disclosure.

[0092] (1) Undervoltage protection circuit

[0093] like Figure 3As shown, the undervoltage protection circuit 141 includes resistors R1, R2, R3, R4, a capacitor C5 and an integrated circuit U1.

[0094] U1 is a voltage detection chip CN301, whose pin 1 is the power ground, pin 2 is the positive terminal of the power supply, pin 3 is the comparator output terminal, and pin 4 is the comparator positive input terminal. U1 has a built-in 1.21V reference voltage and is connected to the comparator negative input terminal. U1 does not require any peripheral devices, and after applying voltage to the signal input terminal pin 4, it can output the comparison level.

[0095] Pin 1 of resistor R1 is connected to the charging and discharging port P-, pin 2 of resistor R1 is connected to pin 1 of resistor R2, pin 2 of resistor R2 is connected to the charging and discharging port P+, capacitor C5 is connected in parallel to both ends of resistor R1, and the common end of resistor R1 and resistor R2 is connected to pin 2 (power supply end VCC) of voltage detection chip U1. Resistors R1 and R2 form a voltage divider network to supply power to voltage detection chip U1, and capacitor C5 is a filter capacitor to eliminate the fluctuation of voltage at both ends of charging and discharging port P+ and P- that interferes with the operation of voltage detection chip U1.

[0096] Resistors R3 and R4 are used as sampling resistors, which are connected in series and connected to the two ends of the charge and discharge ports P+ and P-. The common end of resistors R3 and R4 is connected to the 4-pin LBI (comparison input end) of the voltage detection chip U1. Resistors R3 and R4 send the sampling level of the charge and discharge port voltage to the comparison signal input end of the voltage detection chip U1, and compare it with the reference voltage (1.21V) in the voltage detection chip U1.

[0097] The 3-pin LBO of the voltage detection chip U1 is the comparison output signal terminal, which is connected to the enable terminal EN of the isolated DC / DC module 142. When the sampling level of the input U1 is higher than the reference voltage, U1 outputs a high level, enabling the isolated DC / DC module 142 to output voltage and power the BMS; when the sampling level of the input U1 is lower than the reference voltage, U1 outputs a low level, shuts down the output voltage of the isolated DC / DC module 142, and stops powering the BMS.

[0098] (2) Isolation DC / DC module

[0099] The isolated DC / DC module 142 includes capacitors C1 , C2 , C3 , C4 , a power source U2 , and a power transformer T1 .

[0100] U2 is an isolated DC / DC power supply chip VPS8701, whose pin 1 is the enable terminal, pin 2 is the power ground, pin 3 is the operating frequency control terminal, pins 4 and 6 are the power output terminals, and pin 5 is the power input terminal.

[0101] Pin 2 of U2 is connected to the charging and discharging port P-, pin 5 of U2 is connected to the charging and discharging port P+, capacitors C2 and C2 are connected in parallel to both ends of the charging and discharging ports P+ and P-, and the voltage across the charging and discharging ports P+ and P- is filtered by capacitors C2 and C2 and sent to pins 1 and 5 of the power supply terminals of U2 to provide power to U1; pin 1 of U2 is connected to pin 3 of the enable signal output terminal of U1 of the undervoltage protection circuit 141.

[0102] T1 is a 4-winding high-frequency power transformer VPT87DDF01B, with the primary first winding between pins 1 and 2, the primary second winding between pins 3 and 4; the secondary second winding between pins 5 and 6, and the secondary first winding between pins 7 and 8.

[0103] The primary winding of T1 is connected in series and then connected to the voltage output terminal of the power chip U2, that is, pins 2 and 3 are connected, pin 1 is connected to pin 6 of U2, and pin 4 is connected to pin 4 of U2; pins 6 and 7 of T1 are connected and then connected to GND, pin 5 is connected to the anode of Schottky diode D4, pin 8 is connected to the anode of Schottky diode D3, the cathodes of diodes D3 and D4 are connected to point A and then connected to diode D2 (refer to Figure 1 and Figure 2 ), capacitors C3 and C4 are connected in parallel between point A and GND.

[0104] The power chip U2 converts the terminal voltage of the charging and discharging ports (P+, P-) into a pulse voltage, which is then coupled by the high-frequency isolation transformer T1 and converted into a mutually isolated low voltage with an amplitude of half the terminal voltage of the charging and discharging ports. After being filtered by capacitors C3 and C4, it powers the front-end protection chip and MCU of the BMS.

[0105] Figure 3 The parameters or models of the components in the circuit are as follows:

[0106] Capacitors: C1 and C3 are 10uF / 50V; C2 and C4 are 0.1uF / 50V; C5 is 1uF / 50V;

[0107] Resistors: R1 is 510KΩ; R2 is 1MΩ; R3 is 75KΩ; R4 is 1.05MΩ;

[0108] Diode: D3, D4 are B5819W;

[0109] U1 is CN301; U2 is VPS8701; T1 is VPT87DDF01B;

[0110] Figure 1 The middle resistor Rd is 750Ω, 1206 package; D1 is BAV21W; D2 is BAV21W.

[0111] The power consumption in the circuit of the above embodiment is analyzed below.

[0112] The power consumption of the BMS in the disclosed embodiment is much less than that of the BMS without undervoltage protection. When the battery pack is equipped with a charging and discharging port power supply circuit, there are three main parts that consume the power of the battery pack: (a) the static consumption of the isolated DC / DC module 142, about 12uA (see page 3 of the VPS8701 manual); (b) the consumption of the undervoltage protection circuit 141 is the sum of the consumption of U1 and the consumption of resistors R3 and R4, the consumption of U1 is about 1.8uA, and the consumption of R3 and R4 is 9uA; (c) the leakage current of the undervoltage protection switch K1 is about 0.5uA. Therefore, the overall power consumption of the battery pack in this embodiment is less than 25uA, while the power consumption of the BMS without undervoltage protection is about 800uA. Obviously, the design provided in this embodiment is more conducive to the long-term storage of the battery pack.

[0113] Therefore, the charging port power supply unit added to the BMS in the embodiment of the present disclosure can achieve undervoltage protection of the single cell during the static and discharge period of the battery. This protection can cut off the power supply circuit between the battery and the entire BMS, and only maintain the connection between the undervoltage protection circuit 141 and the battery pack end. The undervoltage protection circuit itself only consumes a dozen microamperes of power, which can maximize the discharge time of the battery pack and extend the life cycle of the battery.

[0114] In summary, the battery management system provided by the present disclosure has the following characteristics:

[0115] (1) It has two power supply circuits on the battery side and the charging and discharging port side, which can realize the single cell undervoltage protection and group end undervoltage protection functions. When the single cell is undervoltage, it can automatically cut off the battery power supply to the BMS, reduce the consumption of the battery pack, and extend the battery life;

[0116] (2) When the battery is protected by single cell undervoltage, pressurizing the charging and discharging port can supply power to the BMS through the power supply circuit on the charging and discharging port side, activating the charging circuit of the battery pack to prevent the battery from falling into a state where it cannot be charged;

[0117] (3) The power supply circuit on the charging port side uses an electronic circuit to realize the cut-off function, which has a simple structure and stable performance. The circuit elements used will not increase the hardware cost significantly. The added circuit itself consumes only a very small amount of electricity and will not increase the additional consumption burden of the battery pack.

[0118] Based on the same inventive concept, the present disclosure also provides a battery power supply with a charging and discharging port, which includes a battery and the aforementioned battery management system. The battery power supply implements single cell undervoltage protection and overall battery pack end low voltage protection, and can automatically activate the battery charging circuit without manual intervention, thereby enhancing the safety and flexibility of the battery power supply.

[0119] The above description is only an embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the scope of the claims of the present disclosure.

Claims

1. A battery management system with a charging and discharging port, characterized in that: include: A front-end sampling and protection unit, a monitoring and communication unit, a battery charging and discharging circuit, and a battery-side power supply circuit and a charging and discharging port-side power supply circuit for supplying power to the front-end sampling and protection unit and the monitoring and communication unit; The battery-side power supply circuit is provided with a power switch K1, and draws power from the battery pack; The front-end sampling protection unit is used to collect the single cell undervoltage signal of the battery pack, and the monitoring communication unit is used to control the power switch K1 to disconnect according to the single cell undervoltage signal, so as to close the battery side power supply circuit; A charging and discharging port power supply unit is provided in the power supply circuit on the charging and discharging port side, the input end of the charging and discharging port power supply unit is connected to the battery charging and discharging circuit, and the output end supplies power to the front-end sampling protection unit and the monitoring communication unit; the charging and discharging port power supply unit turns off the charging and discharging port power supply when the battery group end is undervoltage or the single cell is undervoltage, and turns on the power supply after the charging voltage is applied to the charging and discharging port to activate the battery charging and discharging circuit.

2. The battery management system according to claim 1, characterized in that: The battery side power supply circuit is also provided with a current limiting and voltage dropping resistor Rd and an anti-reverse diode D1; The positive power input terminals of the front-end sampling protection unit and the monitoring communication unit are connected to the positive electrode of the battery through D1, K1 and Rd in sequence.

3. The battery management system according to claim 1, characterized in that: The battery charging and discharging circuit is provided with a sampling resistor Rs and a charging and discharging control switch KM; The control end of the charge-discharge control switch KM is connected to the front-end sampling protection unit and is disconnected after the front-end sampling protection unit loses power.

4. The battery management system according to claim 3, characterized in that: The charge and discharge control switch KM is arranged in the circuit connected to the negative pole of the battery pack.

5. The battery management system according to claim 1, characterized in that: An anti-reverse diode D2 is provided in the power supply circuit on the charging and discharging port side. The charging and discharging port power supply unit includes an undervoltage protection circuit and an isolated DC / DC module. The input end of the undervoltage protection circuit is connected to the charging and discharging port, and the output end is connected to the enable end of the isolated DC / DC module. When the enable end is valid, the isolated DC / DC module converts the power supply voltage input from the charging and discharging port or the battery pack end into an output voltage, and supplies power to the front-end sampling protection unit and the monitoring communication unit through the anti-reverse diode D2.

6. The battery management system according to claim 5, characterized in that: The group terminal voltage protection value Vd1 of the undervoltage protection circuit is greater than n*(Vl+0.075V) and less than n*(Vl+0.25V), wherein n is the number of battery groups and V1 is the undervoltage protection value of the single cell.

7. The battery management system according to claim 5, characterized in that: The undervoltage protection circuit includes a voltage detection chip U1 and a sampling resistor. The sampling resistor sends the sampling level of the charging and discharging port voltage to the voltage detection chip U1. When the sampling level is higher than the reference voltage, the voltage detection chip U1 outputs a high level to enable the isolated DC / DC module to output voltage; when the sampling level is lower than the reference voltage, the voltage detection chip U1 outputs a low level to shut down the isolated DC / DC module output voltage.

8. The battery management system according to claim 5, characterized in that: The isolated DC / DC module includes capacitors C3, C4, a power chip U2 and a high-frequency isolation transformer T1. The power chip U2 converts the voltage at the charging and discharging ports into a pulse voltage, which is converted into a low voltage after coupling with the transformer T1 and is output after filtering by the capacitors C3 and C4.

9. The battery management system according to claim 1, characterized in that: The monitoring communication unit includes an MCU control unit and a DC / DC module. The DC / DC module converts the input power supply voltage into the working voltage of the MCU control unit. The MCU control unit receives the single cell undervoltage signal provided by the front-end sampling protection unit, and controls the on-off of the power switch K1 through the control signal terminal.

10. The battery management system according to claim 9, characterized in that: The battery management system also includes a communication interface unit, which is powered by the DC / DC module and connected to a communication port of the MCU control unit.

11. A battery power source with a charging and discharging port, characterized in that: include: Battery pack, and A battery management system as claimed in any one of claims 1 to 10.

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