CN111591140A

CN111591140A - Battery management system and vehicle

Info

Publication number: CN111591140A
Application number: CN202010412680.3A
Authority: CN
Inventors: 程洋; 卢春宏; 刘春阳
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2020-05-15
Filing date: 2020-05-15
Publication date: 2020-08-28
Also published as: WO2021227589A1

Abstract

The application provides a battery management system and a vehicle, wherein the battery management system is used for controlling the charging and discharging processes of a plurality of battery packs. The battery management system includes: the power supply unit comprises a plurality of power supply units connected in series, the plurality of power supply units correspond to the plurality of battery packs one to one, and each power supply unit is used for being connected with one battery pack. The ith power supply unit in the plurality of power supply units comprises a direct current branch and a switch branch which are connected in parallel, the direct current branch comprises a switch circuit, when the switch circuit is switched off, the switch circuit is used for blocking the charging current and the discharging current of the ith battery pack connected with the ith power supply unit, and i is a positive integer. Through setting up the switch branch road parallelly connected with the direct current branch road, when the group battery trouble that the direct current branch road of part power supply unit is connected, can the bypass direct current branch road, do not influence other power supply units and supply power for the equipment beyond the battery management system, improve the reliability of power supply.

Description

Battery management system and vehicle

Technical Field

The application relates to the field of circuits, in particular to a battery management system and a vehicle.

Background

The battery management system connects a plurality of battery packs in series to supply power to devices such as an electric vehicle. A switch is arranged between every two adjacent battery packs. When the two ends of the battery packs connected in series are short-circuited due to external force such as collision and extrusion, the switch between the adjacent battery packs can be turned off, so that the direct-current high voltage in the battery management system is avoided, and the possibility of safety risks such as battery burnout is reduced.

When only part of the battery packs have faults, the battery management system stops supplying power to the external equipment due to the fact that the switches arranged between the battery packs are disconnected, and the power supply reliability of the battery management system is low. Especially for a battery management system for supplying power to equipment such as an electric automobile and the like, the failure of one battery pack can cause that the vehicle cannot run, and the user experience is low.

Disclosure of Invention

The application provides a battery management system, can be under the condition of partial group battery trouble, for external equipment provides the electric energy, the reliability is higher.

In a first aspect, a battery management system is provided, where the battery management system is used for controlling charging and discharging processes of a plurality of battery packs, and includes a plurality of power supply units connected in series, where the plurality of power supply units are in one-to-one correspondence with the plurality of battery packs, and each power supply unit is used to connect one battery pack in the plurality of battery packs; the power supply unit comprises a plurality of power supply units, wherein the power supply units comprise a direct current branch and a switch branch which are connected in parallel, the direct current branch comprises a switch circuit, when the switch circuit is switched off, the switch circuit is used for blocking the charging current and the discharging current of the battery pack connected with the power supply unit, and i is a positive integer.

Through setting up the switch branch road parallelly connected with the direct current branch road, when the group battery trouble that the direct current branch road of part power supply unit is connected, can the bypass direct current branch road, do not influence other power supply unit and for the equipment power supply outside the battery management system, improve the reliability of battery management system.

With reference to the first aspect, in some possible implementations, the switching branch includes a first switching device, the first switching device includes a first switching tube and a first diode connected in parallel, an anode of the first diode is connected to a cathode of the dc branch, and a cathode of the first diode is connected to an anode of the dc branch.

By arranging the first switch device in the switch branch circuit and reasonably arranging the anode and the cathode of the diode in the first switch device, the switch branch circuit can block the charging current and the discharging current of the battery pack under the condition that the switch branch circuit only comprises one switch device, and the number of the switch devices in the switch branch circuit is reduced.

With reference to the first aspect, in some possible implementations, the switching circuit includes a second switching device, a third switching device; the second switching device comprises a second switching tube and a second diode which are connected in parallel, and the third switching device comprises a third switching tube and a third diode; the second and third switching devices are arranged such that: when the second switching tube and the third switching tube are in a cut-off state, the second diode and the third diode are not conducted simultaneously.

The two switching devices are arranged in the switching circuit, and the directions of the diodes in the switching devices are reasonably arranged, so that the switching circuit can block the charging current and the discharging current of the battery pack.

With reference to the first aspect, in some possible implementations, the second diode is a parasitic diode.

When the switching device uses a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) or other power device, the switching device includes a switching tube and a parasitic diode connected in parallel with the switching tube.

With reference to the first aspect, in some possible implementations, the second switching device, the third switching device, and the ith battery pack are connected in series.

By connecting the two switching devices of the switching circuit in series with the battery pack, the switching circuit can block the charging current and the discharging current of the battery pack.

With reference to the first aspect, in some possible implementations, the direct current branch includes a Direct Current (DC)/DC converter, and the DC/DC converter includes the third switching device.

All or part of the two switching means of the switching circuit may also be located in the DC/DC converter. By using the switching means in the DC/DC converter as switching means in the switching circuit, the number of switching means in the DC branch can be reduced.

With reference to the first aspect, in some possible implementations, the switching circuit includes an overcurrent protector.

The charging current and the discharging current of the battery pack can be blocked by arranging the overcurrent protector.

With reference to the first aspect, in some possible implementation manners, the battery management system further includes an inverter circuit, where the inverter circuit is configured to invert the direct current output by the plurality of power supply units to output an alternating current.

The battery management system can invert the direct current output by the two ends of the plurality of power supply units through the inverter to supply power to external equipment.

With reference to the first aspect, in some possible implementations, the battery management system includes at least one bridge arm connected in parallel, each bridge arm includes two half bridge arms connected in series, each half bridge arm includes a plurality of power supply units connected in series, the battery management system is configured to output an alternating current, and a connection point between the two half bridge arms in each bridge arm is configured to output one phase of the alternating current.

Through the control of the battery management system, the voltage output by two ends of each half-bridge arm in the battery management system can change along with time, so that alternating current is obtained.

In a second aspect, a vehicle is provided, which includes an electric machine, a plurality of battery packs, and the battery management system of the first aspect, the battery management system is configured to receive dc power provided by the plurality of battery packs, and the ac power output by the battery management system is used to drive the electric machine.

Drawings

Fig. 1 is a schematic configuration diagram of a drive circuit of an electric vehicle.

Fig. 2 is a schematic structural diagram of a battery management system according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a battery management system according to an embodiment of the present application.

Fig. 4 is a schematic structural diagram of a power supply unit provided in an embodiment of the present application in a normal discharge condition.

Fig. 5 is a schematic structural diagram of a power supply unit in a normal charging situation according to an embodiment of the present application.

Fig. 6 is a schematic structural diagram of a power supply unit in a case of preventing abnormal charging according to an embodiment of the present application.

Fig. 7 is a schematic structural diagram of a power supply unit provided in an embodiment of the present application in a case of preventing abnormal discharge.

Fig. 8 is a schematic structural diagram of a power supply unit provided in an embodiment of the present application.

Fig. 9 is a schematic structural diagram of a power supply unit provided in an embodiment of the present application.

Fig. 10 is a schematic structural diagram of a vehicle according to an embodiment of the present application.

Fig. 11 is a schematic structural diagram of a battery management system according to an embodiment of the present application.

Fig. 12 is a schematic structural diagram of a battery management system according to an embodiment of the present application.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

The electric vehicle is a vehicle which runs by using a vehicle-mounted power supply as power and driving wheels by using a motor. The safety of the vehicle-mounted power supply affects the safety of the electric vehicle.

The driving circuit 100 includes a battery management system 110 and an inverter 120. The inverter 120 is used to invert Direct Current (DC) power output from the battery management system 110 to drive the motor M.

The battery management system 110 may be disconnected from the inverter 120 when an abnormality occurs in one or more batteries.

The battery management system 110 includes a plurality of battery packs and a plurality of switches connected in series. A switch is arranged between every two adjacent battery packs. Therefore, when the battery management system 110 is subjected to external force such as collision and extrusion to cause short circuit at two ends of a plurality of batteries connected in series, the switch between adjacent battery packs can be turned off, and the safety risks such as battery burnout and the like possibly caused by high direct current voltage in the battery management system 110 due to serial connection of the battery packs are reduced.

When one battery pack fails, the switch between the battery packs is turned off, which results in that the battery management system 110 cannot output electric energy, and the reliability of the battery management system 110 is low.

In addition, the two-level inverter has low efficiency and poor output waveform quality, and has certain influence on the performance of the electric automobile.

In order to solve the above problem, embodiments of the present application provide a battery management system.

Fig. 2 is a schematic structural diagram of a battery management system according to an embodiment of the present application. The battery management system 200 is used for control of the charging and discharging processes of the plurality of battery packs 211.

The battery management system 200 includes a plurality of power supply units 230 connected in series. A plurality of power supply units 230 and a plurality of battery packs 211. Each power supply unit 230 is used to connect one battery pack 211. Each power supply unit 230 may also include a battery pack 211.

All or part of the plurality of power supply units 230 includes a dc branch 210 and a switching branch 220 connected in parallel.

The dc branch 210 includes a switching circuit 212. The switching circuit 212 is used to transmit a charging current and a discharging current of the battery pack 211. The dc branch 210 may also include a battery pack 211.

The battery 211, which may also be referred to as a power storage device, is used to store electrical energy and may include one or more batteries. The charging current of the battery pack 211 is the current flowing through the battery pack 211 when the battery pack 211 is charged. The discharge current of the battery pack 211, i.e., the current flowing through the battery pack 211 when discharging the battery pack 211, supplies power to circuits outside the battery management system 200.

The switching circuit 212 is used to transmit a charging current and a discharging current of the battery pack 211. The switching circuit 212 is used to transmit a charging current when the battery pack 211 is normally charged. The switching circuit 212 is used to transmit a discharge current when the battery pack 211 is normally discharged.

When the switch is turned on, the switch can be used for current circulation. When the switch is turned off, the circuit may be opened to interrupt the current flowing through the switch, i.e., to block the flow of current. Therefore, the switching circuit 212 may be used to block the charging current and the discharging current of the battery pack to which the power supply unit in which the switching circuit 212 is connected. When an abnormality occurs in the battery pack 211, the charging current or the discharging current of the battery pack is blocked by turning off the switch circuit 212. An open circuit, which may also be referred to as an open circuit, refers to a state in which the entire circuit is broken at some point.

Series connection (series connection) is one of the basic ways to connect circuit elements. By adopting the series connection mode, the components (such as a resistor, a capacitor, an inductor, an electric appliance and the like) or circuits formed by the components can be sequentially connected end to end one by one. The plurality of power supply units 230 are connected in series, that is, the positive pole of one power supply unit 230 is connected to the negative pole of another power supply unit 230.

Parallel connection is a connection mode among elements, and is characterized in that 2 or two component devices are connected end to end, and the tail and the head are also connected. The dc branch 210 and the switching branch 220 are connected in parallel, and when a battery pack in the dc branch 210 fails, the dc branch 210 can be bypassed by the switching branch 220.

When the battery pack has a fault, the switch circuit 212 is used for avoiding the influence of the fault of the battery pack on other components in the battery management system 200, and the switch circuit 212 is used for bypassing the direct current branch 210 where the battery pack is located, so that the normal operation of other components in the battery management system 200 is not influenced, and the reliability of the battery management system 200 is improved.

When the switching circuit 212 is turned off, the switching circuit 212 serves to block the charging current and the discharging current of the battery pack 211, and therefore, the battery management system 200 can achieve higher reliability in both the charging condition and the discharging condition.

Under the charging condition, the external power supply can be controlled to charge all or part of the battery packs by monitoring the charging condition of each battery pack and controlling the switch circuit 212 and the switch branch 220, so that the active equalization control is realized, the charging efficiency is improved, the difference among the battery packs is weakened, and the service life of the battery packs is prolonged.

The number of the power supply units 230 may be set such that the maximum voltage of each power supply unit 230 is equal or unequal.

The number of the power supply units 230 may be set according to the maximum voltage value of the battery management system 200. For example, the number of power supply units 230 is such that the maximum voltage of each power supply unit 230 is less than or equal to a safe voltage (e.g., the safe voltage may be 60 volts (V), 36V, or the like).

In some embodiments, each power supply unit 230 may include a dc branch 210 and a switching branch 220 connected in parallel. That is, the switching legs 220 may correspond to the power supply units 210 one to one. Thus, each battery pack 211 can be bypassed, further improving the reliability of the battery management system 200. Battery pack 211 is bypassed, i.e., battery pack 211 does not affect the normal operation of battery management system 200.

In general, the switching circuit may use a power device to implement a switching function. The power device may also be called a power electronic device (power electronic device) or a power semiconductor device, and is mainly used for a high-power electric energy conversion and control circuit of a power device, and the high power generally refers to a case where a current is tens to thousands of amperes or a voltage is hundreds of volts or more.

The switching circuit may include a switching device. The switching device can adopt a voltage-driven power device and can also adopt a current-driven power device.

Common voltage-driven power devices include insulated-gate bipolar transistors (IGBTs), metal-oxide semiconductor field effect transistors (MOSFETs), Integrated Gate Commutated Thyristors (IGCTs), and the like.

The switching circuit 212 may include a switching device. Each switching device may be a power device. The power device is used for controlling whether the two ports of the power device are connected or not. In power devices such as MOSFETs, IGBTs, etc., a parasitic diode is also present between the two ports. That is, a power device is connected in parallel with the parasitic diode.

Due to the parasitic diode, when the power device is turned off, current may flow from the anode of the parasitic diode to the cathode of the parasitic diode, and the turn-off cannot be completely realized.

The battery pack 211 may be discharged to power other devices. The battery pack 211 also needs to be charged. In both cases of discharging and charging the battery pack 211, the current flowing through the battery pack 211 is in opposite directions.

The switch circuit 212 can cut off the current flowing through the battery pack 211 in both the charging and discharging of the battery pack.

The switching circuit 212 may include two switching devices. Each switching device comprises a switching tube and a diode which are connected in parallel. The arrangement of the two switching devices is such that the diodes in the two switching devices are not conducting simultaneously when the switching tubes in both switching devices are in the off-state.

When the switching branch 220 is open, the switching branch 220 allows the charging current and the discharging current of the battery pack 211 to flow through the dc branch 210. When the switching branch 220 is turned on, the switching branch bypasses the dc branch.

The switching leg 220 may include one or more switching devices. For example, the switching device in the switching branch 220 includes a switching tube and a diode connected in parallel, wherein an anode of the diode is connected to a cathode of the power supply unit 230, and a cathode of the diode is connected to an anode of the power supply unit 230. The diode in the switching device may be a parasitic diode of the switching tube, or may be a diode provided in parallel with the switching tube in order to increase a current path.

In order to improve the voltage stability of the output of the dc branch 210, the dc branch 210 may further include a capacitor. The capacitor may be connected in parallel with the battery pack.

The temperature of the battery pack 211, the current flowing through the battery pack 211, and the like can be detected in real time, and when a preset condition is met, the switch circuit 212 is turned off, and the switch branch 220 is controlled to be turned on or off.

Illustratively, the switching circuit 212 may include a temperature sensitive switch. The temperature sensitive switch may be connected in series with the battery pack 211. A temperature sensitive switch may be connected to the positive electrode or the negative electrode of the battery pack 211. When the temperature exceeds a safety value, the temperature sensitive switch is triggered to be turned off, so that the current flowing through the battery pack 211 can be blocked.

The battery management system 200 may be used to output direct current. In the case that the battery management system 200 is normally discharged, the switching circuit 212 in each power supply unit may be controlled to be turned on and the switching branch 220 may be turned off, so that direct current may be output across the battery management system 200. Reference may be made in particular to the description of fig. 11.

The voltage of the dc power output by the battery management system 200 may vary over time. In the case that the battery management system 200 is normally discharged, the number of the switch branches 220 that are turned on may be periodically controlled, so as to control the voltage value across the battery management system 200, so that the voltage value across the battery management system 200 periodically changes, for example, through the control of the switch branches 220 in each power supply unit and the switch tubes in the switch circuit 212. So that ac power can be obtained across the load according to the time-varying dc power output by the battery management system 200, as can be seen in particular in the description of fig. 12. It should be appreciated that when switching leg 220 is on, switching circuit 212 is off.

Fig. 3 is a schematic structural diagram of a power supply unit according to an embodiment of the present application.

The switching circuit 212 may include a switching device Q1 and a switching device Q2 in series.

The switching device Q1 includes a switching tube and a diode connected in parallel. The switching device Q2 includes a parallel switching tube and a diode.

The switching device Q1, the switching device Q2, and the battery pack 211 are connected in series.

For example, the switching device Q1 and the switching device Q2 may be both located at the positive pole or the negative pole of the battery pack 211. That is, one of the switching devices Q1 and Q2 has one end connected to the positive electrode or the negative electrode of the battery pack 211 and the other end connected to the other switching device.

The anode of the diode in the switching device Q1 may be connected to the anode of the diode in the switching device Q2, or the cathode of the diode in the switching device Q1 may be connected to the cathode of the diode in the switching device Q2. That is, the diode in the switching device Q1 and the diode in the switching device Q2 may be formed in a pair.

For example, one of the switching devices Q1 and Q2 may be connected to the positive pole of the battery pack 211, and the other may be connected to the negative pole of the battery pack 211.

The anode of the diode of the switching device Q1 is connected to the anode of the battery pack 211, and the anode of the diode of the switching device Q1 is connected to the cathode of the battery pack 211.

Alternatively, the cathode of the diode of the switching device Q1 is connected to the anode of the battery pack 211, and the cathode of the diode of the switching device Q1 is connected to the cathode of the battery pack 211.

Through setting up switching device Q1 and Q2 to when making the switch tube in these two switching device all cut off, two diodes in these two switching device are not switched on simultaneously, thereby switching circuit 212 can realize turning off completely, break off the connection of other components and parts in group battery 211 and the battery management system 200, avoid the return circuit that group battery 211 and other components and parts formed, cause more serious influence to battery management system 200 when avoiding group battery 211 trouble, improve battery management system 200's security.

The switching leg 220 may include two switching devices. Each switching device may comprise a switching tube and a diode connected in parallel. The arrangement of the two switching devices in the switching branch 220 is such that: when the switching tubes in the two switching devices are both in the off state, the diodes in the two switching devices are not conducted simultaneously.

The switching branch 220 may also include only the switching device Q3, which may achieve an effective turn-off. The switching device Q3 includes a switching tube and a diode connected in parallel. The anode of the diode in the switching device Q3 is connected to the cathode of the dc link 210, and the cathode of the diode in the switching device Q3 is connected to the anode of the dc link 210.

The positive and negative poles of the dc branch 210 may be determined according to the positive and negative poles of the battery pack connected in the power supply unit 230. When the battery pack is discharged, current flows from the positive electrode of the battery pack through the positive electrode of the dc branch 210, and flows to the negative electrode of the battery pack through the negative electrode of the dc branch 210. Similarly, the positive and negative poles of the power supply unit 230 may also be determined according to the positive and negative poles of the battery pack. The positive electrode of the dc branch 210 may be connected to the positive electrode of the power supply unit 230. The dc branch 210 may be connected to a negative electrode of the power supply unit 230.

The switching device Q3 can block the current flowing through Q3 to achieve an effective turn-off in case of battery charging or battery discharging. In particular, reference may be made to the description of fig. 4 to 8.

When the power supply unit 230 is normally discharged, the switching tubes in the switching devices Q1 and Q2 are turned on, and the switching tube in the switching device Q3 is turned off.

The switching tubes of the switching devices Q1 and Q2 are turned on, the voltage across the switching device Q3 is equal to the voltage across the battery pack, the anode of the diode in the switching device Q3 is connected to the cathode of the battery pack, the cathode of the diode is connected to the anode of the battery pack, and the diode is turned off.

Accordingly, current flows from the negative electrode of the power supply unit 230 to the positive electrode of the power supply unit 230 through the battery pack, the switching device Q2, and the switching device Q1.

When the power supply unit 230 is normally charged, the switching tubes of the switching devices Q1 and Q2 are turned on, and the switching tube of the switching device Q3 is turned off.

In the case of charging, the positive electrode of power feeding unit 230 is connected to the positive electrode of the applied voltage, and the negative electrode of power feeding unit 230 is connected to the negative electrode of the applied voltage. The switching tubes of the switching devices Q1 and Q2 are turned on, the voltage across the switching device Q3 is equal to the voltage value of the applied voltage, and the diode of the switching device Q3 is turned off.

Accordingly, current flows from the positive pole of the power supply unit 230 to the negative pole of the power supply unit 230 through the battery pack, the switching device Q1, and the switching device Q2.

When an abnormality occurs in the battery pack in the power supply unit, the charging of the battery pack can be prevented by controlling the switching device in the power supply unit when charging the battery pack. To prevent charging of the battery pack in abnormal situations, the switching tubes in both switching devices Q1 and Q2 are turned off. Since the diodes in the switching devices Q1, Q2 are not turned on simultaneously, current does not flow through the battery pack.

For example, the switching tube in the switching device Q3 may be controlled to be turned off. In the case of charging, the positive electrode of power feeding unit 230 is connected to the positive electrode of the applied voltage, and the negative electrode of power feeding unit 230 is connected to the negative electrode of the applied voltage. The switching tubes of the switching devices Q1 and Q2 are turned off, the voltage across the switching device Q3 is equal to the voltage value of the applied voltage, and the diode of the switching device Q3 is turned off. Therefore, no current flows in the power supply unit 230.

The battery management system 200 includes a plurality of power supply units 230 connected in series. Therefore, when the battery pack connected to the battery management system 200 is charged, the switching tubes of the switching devices Q1, Q2, Q3 in the at least one power supply unit 230 are controlled to be turned off, and the charging process may be stopped.

For example, the switching tube in the switching device Q3 may be controlled to conduct. At this time, a current flows from the positive electrode of the power supply unit 230 to the negative electrode of the power supply unit 230 through the switching device Q3. Therefore, when a certain battery pack in the battery management system 200 fails, the switching device Q3 in the power supply unit in which the battery pack is located may be controlled to be turned on, so as to bypass the battery pack, and thus, charging of the battery packs in other power supply units is not affected.

When the battery pack in the power supply unit 230 is abnormal, if a plurality of battery packs connected to the battery management system are discharged, the battery pack can be disconnected from other elements in the battery management system by controlling the switch device in the power supply unit, so that the influence of the battery pack on other power supply units in the battery management system is avoided.

In order to prevent the battery pack from discharging in the event of an abnormal condition of the battery pack and avoid one battery pack from influencing the normal operation of other power supply units in the battery management system, the switching tubes in the switching devices Q1 and Q2 can be controlled to be turned off. Because the diodes in the switching devices Q1 and Q2 are not conducted at the same time, current does not flow through the battery pack, and the influence of the battery pack on other power supply units is avoided.

For example, the switching tube in the switching device Q3 may be controlled to be turned off. In the case of battery discharge, since the switching tubes in the switching devices Q1 and Q2 are turned off, the voltage across the switching device Q3 is 0, and the diode in the switching device Q3 is turned off. Therefore, no current flows in the power supply unit 230.

The battery management system 200 includes a plurality of power supply units 230 connected in series. Therefore, when discharging the battery management system 200, the switching tubes of the switching devices Q1, Q2, Q3 in the at least one power supply unit 230 are controlled to be turned off, and the charging process may be stopped.

For example, the switching tube in the switching device Q3 may be controlled to conduct. At this time, a current flows from the positive electrode of the power supply unit 230 to the negative electrode of the power supply unit 230 through the switching device Q3. Therefore, when a certain battery pack connected to the battery management system 200 fails, the switching device Q3 in the power supply unit in which the battery pack is located may be controlled to be turned on, so as to bypass the battery pack, and thus, power supply of circuits or devices outside the battery management system 200 to the battery packs connected to other power supply units may not be affected.

The switching circuit 212 may include an overcurrent protection circuit. The overcurrent protection circuit is used for realizing turn-off when the current exceeds a preset value.

The overcurrent protection circuit may be, for example, a fuse F. The fuse may also be referred to as a fuse. The fuse F is used as a switching device, and when the current flowing through the battery pack 211 exceeds a fuse blowing current, the current flowing through the battery pack is blocked by blowing the fuse.

By providing the overcurrent protection circuit in the switch circuit 212, when the current is too large, the fuse F can break a loop formed by the battery pack 211 and other components in the battery management system 200, thereby improving the safety of the battery management system 200.

The switching circuit 212 may also switch the device Q1. In the case of battery pack charging, the switching device Q1 may be controlled to turn on or off, thereby controlling the voltage across the battery management system 200.

The direct current branch 210 may include a battery pack and a DC/DC converter and battery pack 211.

The DC/DC converter may be a boost (boost) type DC/DC converter, or a buck (buck) -boost type DC/DC converter, or the like. A boost type DC/DC converter will be described as an example.

The boost type DC/DC converter may include an inductor L, a switching device Q4, a switching device Q5, and an output capacitor C. The switching device Q4 includes a switching tube and a diode connected in parallel. The switching device Q5 includes a switching tube and a diode connected in parallel.

When the battery pack 211 is discharged, when the switch transistor of the switching device Q5 is turned on, the switching device Q5 bypasses the output capacitor C and the switching device Q4, and the battery pack 211 charges the inductor. When the switch of the switching device Q5 is turned off, the inductor L discharges, and the inductor L and the battery pack 211 together charge the output capacitor C.

The first end of the inductor L is connected with the anode of the battery pack. A second terminal of the inductor L is connected to the anode of the diode of the switching device Q4 and the cathode of the diode of the switching device Q5. The cathode of the diode in the switching device Q4 is connected to the first terminal of the output capacitor C, and the second terminal of the output capacitor C is connected to the anode of the diode in the switching device Q5 and to the first terminal of the switching branch 220.

The dc branch 210 also includes a switching device Q6. The switching device Q6 includes a switching tube and a diode connected in parallel.

The anode of the diode in the switching device Q4 may be connected to the cathode of the diode in the switching device Q6. The anode of the diode in the switching device Q6 is connected to the second terminal of the switching leg 220.

Therefore, the battery pack 211 and the boosting-type DC/DC converter may serve as a direct current power supply of the power supply unit 230.

Alternatively, the switching device Q6 may be disposed between the junction of the negative terminal of the battery pack, the switching device Q5, the second end of the output capacitor, and the switching leg 220.

In the case of normal charging or discharging of the battery pack, the switching tube in the switching device Q3 is turned off.

In the case of normal discharge of the battery pack, the switching tube in the switching device Q6 is turned on, and each switching device in the step-up DC/DC converter is turned on or off according to the principle of step-up.

Under the condition that the battery pack is normally charged, the switching tubes in the switching device Q6 and the switching device Q4 are turned on, and the switching tube in the switching device Q5 is turned off, so that an external voltage is applied to two ends of the battery pack.

When the battery pack is abnormal, the switching tubes in the switching device Q6 and the switching device Q4 are cut off, so that the current flowing through the battery pack is blocked, and the influence of the battery pack on other components of the battery management system is avoided. The switching tube in the switching device Q3 can be turned on or off according to the requirement.

Illustratively, the boost type DC/DC converter may further include a switching device Q6. The switching device Q6 may be located between the cathode of the diode in the switching device Q4 and the first terminal of the output capacitor C. The anode of the diode in switching device Q6 is connected to the cathode of the diode in switching device Q4.

Alternatively, the switching device Q6 may be located between the anode of the diode in the switching device Q4 and the anode of the battery pack. The cathode of the diode in switching device Q6 is connected to the cathode of the diode in switching device Q4.

When the battery pack is normally charged or discharged, the switching tube in the switching device Q3 is turned off.

When the battery pack is normally discharged, the switching devices Q4 and Q6 are turned on or off according to the principle of the boost DC/DC converter.

When the battery pack is normally charged, the switching device Q4 and the switching device Q6 are turned on, so that an applied voltage is applied across the battery pack.

When the battery pack is abnormally charged or discharged, the switching tubes in the switching device Q4 and the switching device Q6 are turned off, and current flowing through the battery pack is blocked. The switching tube in the switching device Q3 is turned on or off according to the requirement.

The vehicle 2000 includes an electric machine 2030, a plurality of battery packs 2010, and a battery management system 2020.

The battery management system 2020 is configured to receive dc power provided by the plurality of battery packs. The ac power output by the battery management system 2020 is used to drive the motor 2030.

The structure of the battery management system 2020 can be specifically referred to fig. 11 or fig. 12.

Fig. 11 is a schematic structural diagram of a vehicle according to an embodiment of the present application. The battery management system 1100 may also be referred to as a drive device or a drive system.

The battery management system 1100 includes a plurality of power supply units 230 and inverters 1120 connected in series. Both ends of the plurality of power supply units 230 connected in series output direct current. The inverter circuit is configured to invert the dc power output from the two ends of the plurality of power supply units 230 connected in series, and output ac power to drive the motor. The drive system 1100 may be applied in an electric vehicle.

The structure of each power supply unit 230 may be the same or different. The structure of the power supply unit 230 can be seen in fig. 3, 8, and 9. The description will be made by taking, as an example, a power supply unit shown in fig. 3 for each power supply unit.

A plurality of series-connected power supply units 230 may employ a distributed module. The maximum voltage of each power supply unit 230 may be controlled within a safe voltage (60V).

When a fault such as a short circuit occurs in the battery management system 1100, the first switch circuit 212 blocks the current flowing through the battery packs 211, so that the plurality of battery packs 211 are prevented from forming a low-impedance loop, the possibility of burning the battery management system 1100 is reduced, and the safety of the battery management system 1100 is improved.

Each power supply unit 230 includes a dc branch 210 and a switching branch 220 connected in parallel. The dc branch 210 includes a battery pack 211 and a switching circuit 212.

Each switching circuit 212 includes two switching devices, each comprising a switching tube and a diode in parallel. By arranging the two switching devices, when the switching tubes of the two switching devices are both cut off, the diodes of the two switching devices are not conducted at the same time. Thereby, the switching circuit 212 can be made to block the current flowing through the battery pack 211, achieving a reliable turn-off.

Fig. 12 is a schematic configuration diagram of a battery management system. The battery management system 1200 may also be referred to as a modular multilevel converter, drive, or drive system.

The battery management system 1200 is used to convert a low dc voltage in each power supply unit 1210 into a high ac voltage.

The battery management system 1200 includes at least one leg, each leg including a first half leg and a second half leg connected in series, each of the plurality of first half legs and the plurality of second half legs including a plurality of power supply units.

The battery management system 1200 is configured to output ac power, and a connection point between two half bridge arms in each bridge arm is configured to output one-phase ac power of the ac power.

The number of arms in battery management system 1200 is equal to the number of phases of the ac power output by battery management system 1200.

The first end of each first half bridge arm is connected to the first node, and the first end of each second bridge arm is connected to the second node. In each bridge arm, a connection point between the second end of the first half bridge arm and the second end of the second half bridge arm is used for outputting alternating current.

Each half-bridge arm may further comprise an inductor for filtering the output alternating current.

The number of power supply units 1210 in each half bridge arm may be equal or unequal. In the case that the number of the power supply units 1210 in each half bridge arm is not equal, when the battery management system 1200 operates to output the ac power, the half bridge arms including a larger number of the power supply units 1210 have redundancy.

The battery management system 1200 may be used to drive a motor in an electric vehicle.

In the battery management system 1200, each power supply unit 1210 may be the same or different, and the configuration of the power supply unit shown in fig. 3, 8, or 9, or the like may be employed.

Taking the example that the battery management system 1200 includes 3 bridge arms (i.e., the driving system 1200 includes 6 half bridge arms for outputting three-phase ac power), each power supply unit 1210 adopts the structure of the power supply unit 230 shown in fig. 3.

When the electric vehicle is running, if the battery pack 211 in one power supply unit 1210 is short-circuited, the switch circuit 212 is turned off and the switch branch 220 is opened for the power supply unit 1210 to isolate the battery pack 211.

Meanwhile, one power supply unit 1210 can be selected in each of the other five half-bridge arms, and for the power supply unit 1210, the switching circuit 212 can be turned off, and the switching branch 220 can be turned on. That is to say, other 5 half-bridge arms of the battery management system 1200 can be in a redundant operation state, so that the safe operation of the whole battery management system 1200 is ensured, and the reliability of the battery management system 1200 is improved.

The battery management system 1100 or the battery management system 1200 is adopted to drive the motor in the electric automobile, so that the safety and the stability of the electric automobile can be improved.

During the operation (i.e., discharging) or charging of the electric vehicle, if the battery pack has a serious fault, such as a temperature exceeding a safe temperature, the switching circuit 212 in each power supply unit 230 may be quickly turned off to block the current flowing through each battery pack. Meanwhile, the switch branch 220 is turned off, so that high configurations are formed among the power supply units, and the direct-current high-voltage formed by connecting a plurality of battery packs in series in the battery management system 1100 is rapidly reduced to be within the safe voltage, thereby preventing further fault diffusion, adapting to a severe insulation failure environment and increasing the escape time of personnel.

During the operation or charging process of the electric vehicle, if some small faults occur in the battery pack, for example, the voltage across one or more battery packs or the current flowing through one or more battery packs exceeds a safe value, but the temperature of the battery pack meets the safe temperature requirement, the switching circuit 212 in the power supply unit where the faulty battery pack is located can be controlled to be turned off, and the current flowing through each battery pack can be blocked. Meanwhile, the switch branch 220 is turned on, so that other power supply units operate normally, and the reliability of the driving device is improved. So that the electric vehicle can be driven to a maintenance point.

In the battery pack charging process of the electric automobile, the switch branch 220 in the power supply unit of the control part can be conducted, and the battery pack in other power supply units can be charged only, so that active equalization control is realized, the charging efficiency is improved, and the service life of the battery pack is prolonged.

The embodiment of the application also provides a control method of the battery management system, which comprises the following steps of; generating a control signal for controlling the battery management system as described above; and sending the control signal to the battery management system.

The battery management system includes: the power supply unit comprises a plurality of power supply units connected in series, and each power supply unit is used for connecting a battery pack. The ith power supply unit in the plurality of power supply units comprises a direct current branch and a switch branch which are connected in parallel, the direct current branch comprises a switch circuit, the switch circuit is used for blocking the charging current and the discharging current of the battery pack, and i is a positive integer.

Optionally, when the battery pack has a fault, the control signal is used to control the switching circuit to be open, and the control signal is also used to control the switching branch to be conductive.

Optionally, when the battery pack has a fault, the control signal is used to control the switching circuit to be opened, and the control signal is also used to control the switching branch to be opened.

The embodiment of the application also provides a control device of the battery management system, which comprises a processor and a communication interface. The processor is configured to generate a control signal, where the control signal is used to control the switching circuit and the switching branch in the battery management system, so that the battery management system outputs ac power or dc power. The communication interface is used for sending the control signal to the battery management system.

Embodiments of the present application further provide a computer program storage medium, which is characterized by having program instructions, when the program instructions are directly or indirectly executed, the method in the foregoing is implemented.

An embodiment of the present application further provides a chip system, where the chip system includes at least one processor, and when a program instruction is executed in the at least one processor, the method in the foregoing is implemented.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A battery management system for controlling the charging and discharging processes of a plurality of battery packs, the battery management system comprising: the power supply units are connected in series, correspond to the battery packs one by one, and are used for connecting one battery pack in the battery packs;

the ith power supply unit in the plurality of power supply units comprises a direct current branch and a switch branch which are connected in parallel, the direct current branch comprises a switch circuit,

when the switch circuit is turned off, the switch circuit is used for blocking the charging current and the discharging current of the ith battery pack connected with the ith power supply unit, wherein i is a positive integer.

2. The battery management system of claim 1, wherein the switching branch comprises a first switching device, the first switching device comprises a first switching tube and a first diode connected in parallel, an anode of the first diode is connected to a cathode of the dc branch, and a cathode of the first diode is connected to an anode of the dc branch.

3. The battery management system according to claim 1 or 2, wherein the switching circuit comprises a second switching device, a third switching device;

the second switching device comprises a second switching tube and a second diode which are connected in parallel, and the third switching device comprises a third switching tube and a third diode;

the second and third switching devices are arranged such that: when the second switching tube and the third switching tube are in a cut-off state, the second diode and the third diode are not conducted simultaneously.

4. The battery management system of claim 3, wherein the second switching device, the third switching device, and the ith battery pack are connected in series.

5. The battery management system of claim 3, wherein the direct current branch comprises a direct current/direct current (DC/DC) converter, the DC/DC converter comprising the third switching device.

6. The battery management system of any of claims 3-5, wherein the second diode is a parasitic diode.

7. The battery management system of claim 1 or 2, wherein the switching circuit comprises an overcurrent protector.

8. The battery management system according to any one of claims 1 to 7, further comprising an inverter circuit for inverting the direct current output from both ends of the plurality of power supply units to output an alternating current.

9. The battery management system according to any one of claims 1 to 7, comprising at least one bridge leg connected in parallel, each bridge leg comprising two half bridge legs connected in series, each half bridge leg comprising a plurality of power supply units connected in series, the battery management system being configured to output an alternating current, and a connection point between the two half bridge legs in each bridge leg being configured to output one phase of the alternating current.

10. A vehicle comprising an electric machine, a plurality of battery packs, and the battery management system of claim 8 or 9, wherein the battery management system is configured to receive dc power from the plurality of battery packs, and wherein ac power from the battery management system is configured to drive the electric machine.