Protection circuit for a battery management system

Abstract

Systems and methods are provided for a battery management system (BMS) having a protection circuit. In one example, a vehicle battery system can include a BMS including a cutoff circuit electrically coupled to the protection circuit, and a battery pack having a positive power supply line electrically coupled to the cutoff circuit, where the protection circuit can include each of an input electrically coupled to a control input of the cutoff circuit, an output electrically coupled to an output of the cutoff circuit, and a control input of the protection circuit electrically coupled to the output of the cutoff circuit. In some examples, the protection circuit can further include a low leakage current transistor configured to maintain the cutoff circuit in an open state upon detection of a reverse bias voltage. In this way, the protection circuit can mitigate accidental turn-on of the cutoff circuit.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to each of U.S. Provisional Application No. 63 / 036,346, filed June 8, 2020, entitled "Protection Circuit for Battery Management System," and U.S. Provisional Application No. 63 / 042,963, filed June 23, 2020, entitled "Protection Circuit for Battery Management System." The entire contents of each of the foregoing applications are incorporated herein by reference for all purposes. Technical Field

[0003] This specification generally relates to a battery management system including protection circuitry, and particularly to a battery management system for battery packs in vehicles.

[0004] Background Technology and Summary of the Invention

[0005] Lithium-ion rechargeable batteries are commonly used for starting and powering electric and hybrid electric vehicles. Depending on power requirements and applications, multiple lithium-ion batteries can be assembled into a battery pack. For example, a 48V battery pack can be installed in a battery-assisted hybrid vehicle (BAHV) to provide power to the BAHV during low engine load operations such as coasting, braking, and idling.

[0006] During vehicle maintenance or battery pack replacement, the positive and negative leads can be disconnected from the battery pack and then reconnected to the existing battery pack or to a new battery pack. However, in some cases, the positive and negative leads may be connected in reverse to the terminals of a given battery pack. In other cases, a negative voltage drop may occur at the positive terminal of the battery pack during vehicle operation, such as voltage noise. In either case, one or more power control devices in the vehicle's Battery Management System (BMS) (e.g., Metal-Oxide-Semiconductor Field-Effect Transistors, MOSFETs) may be accidentally turned on, resulting in a reverse bias of the applied potential difference and unintentionally discharging the battery pack. This reverse bias may degrade one or more power control devices in the BMS, causing the drive power control devices to fail to switch operating states as expected.

[0007] Therefore, protection circuits have been developed to mitigate reverse bias voltage. As an example, a diode can be placed in series with the battery pack so that no current flows when a reverse bias voltage is applied. However, the forward voltage drop across the diode may limit the voltage available to the driver IC. As another example, an additional MOSFET can be placed in the power (positive power) line (between the series-connected battery pack and the electrical load) or the ground loop (between the series-connected electrical load and the battery pack), where the body diode of the additional MOSFET is oriented in the direction of the expected current flow during battery operation. Thus, when the battery pack is incorrectly connected / installed, the body diode can short-circuit the reverse bias voltage to ground to provide reverse bias protection, and the body diode itself may short-circuit during the expected battery pack operation. However, implementing an additional MOSFET in the protection circuit can be associated with further control complexity at the driver IC and may result in a corresponding increase in cost. Furthermore, reverse polarity connections may induce higher currents that may not be handled by any given MOSFET, resulting in a less than expected reverse bias voltage condition.

[0008] The inventors have recognized the aforementioned problems and have identified solutions for at least partially addressing them. In one example, a vehicle battery system is provided, comprising: a battery management system (BMS) including a cutoff circuit electrically coupled to a reverse bias protection circuit; and a battery pack having a plurality of stacked battery cells, the positive power line of the battery pack being electrically coupled to the cutoff circuit, wherein the reverse bias protection circuit includes each of an input to a control input electrically coupled to the cutoff circuit, an output electrically coupled to an output of the cutoff circuit, and a control input electrically coupled to the output of the cutoff circuit. In this way, the vehicle battery system can be protected from reverse bias voltage conditions without the need for expensive components or complex control circuitry.

[0009] In one example, a vehicle battery system is provided having a battery pack coupled to a battery management system (BMS). Specifically, the positive power line of the battery pack can be electrically coupled to the drain terminal of a MOSFET included in the BMS. Furthermore, the gate and source terminals of the MOSFET can be electrically coupled to a reverse bias protection circuit. Therefore, in a higher current environment accompanied by the application of a reverse bias voltage, the gate-source voltage (Vo) of the MOSFET... GS The threshold voltage (V) can be maintained by directing current to a low-leakage-current transistor in the reverse-biased protection circuit. th Therefore, even when a reverse bias voltage is applied, the reverse bias protection circuit can remain in the off state in the MOSFET.

[0010] In some examples, the collector-emitter voltage (V0) of the low-leakage-current transistor electrically coupled to the MOSFET is adjusted accordingly. CE ), can make the V of the MOSFET GS It remains near zero. Specifically, the Zener diode can be further coupled to each of the emitter and base terminals of the low-leakage-current transistor to increase the base-emitter voltage (V) across it. BE This switches the low-leakage-current transistor to the on state. Once on, the low-leakage-current transistor can switch V to the on state. CE Maintaining voltage spikes at low levels effectively controls voltage spikes in the vehicle's battery system.

[0011] It should be understood that the above-described invention is provided to introduce, in a simplified form, the selection of concepts further described in the detailed description. This does not imply the identification of key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0012] Figure 1A A schematic diagram of an exemplary battery pack assembly is shown.

[0013] Figure 1B A schematic diagram of an exemplary battery pack assembly is shown, in which at least a portion of the outer casing is removed, thereby exposing multiple stacked battery cells.

[0014] Figure 2 A general block diagram of a vehicle battery system, including a battery management system, is shown.

[0015] Figure 3 A schematic diagram of a circuit system including protection circuitry in a battery management system is shown.

[0016] Figure 4 A flowchart is shown for a method of managing current flow through a cut-off circuit during reverse bias voltage conditions.

[0017] Figure 5 An exemplary operation sequence of the BMS is shown. Detailed Implementation

[0018] The following description relates to systems and methods for protection circuitry for battery packs, such as lithium-ion battery packs used to power electric or hybrid electric vehicles. A lithium-ion battery pack may include multiple lithium-ion battery cells assembled in a stacked configuration. As an example, a lithium-ion battery pack may be a 48V battery pack used to start or power a battery-assisted hybrid vehicle (BAHV). Furthermore, protection circuitry may be included in a battery management system (BMS) coupled to the lithium-ion battery pack.

[0019] Specifically, the protection circuit can maintain the disconnect circuit in an open state, for example, when an unexpected reverse bias voltage is applied due to a reverse polarity event. The disconnect circuit can include one or more field-effect transistors (FETs), such as metal-oxide-semiconductor FETs (MOSFETs), junction-gate field-effect transistors (JFETs), other types of transistors, or combinations thereof. In one example, the disconnect circuit can be a single MOSFET. In additional or alternative examples, the protection circuit can include a low-leakage-current transistor, such as a bipolar junction transistor (BJT), which can maintain a near-zero collector-emitter voltage (V0) when a reverse bias voltage is applied to the source terminal of the MOSFET. CE The gate-source voltage (V) of the MOSFET GS Maintain at the threshold voltage (V) th The following applies. In this way, the disconnect circuit, and therefore the BMS and lithium-ion battery pack, can be protected from voltage spikes caused by reverse polarity conditions such as negative electrical noise or miscoupling of the positive and negative leads to the terminals of the lithium-ion battery pack.

[0020] As used herein, when referring to two components of a circuit, unless otherwise stated, "coupled" can mean "electrically coupled." Therefore, when referring to two components of a circuit, "directly coupled" can mean that the two components are electrically coupled, and no electrical components (e.g., resistors, transistors, capacitors, etc.) other than electrical conductors (such as wires and / or busbars) are positioned between the two components. Furthermore, a transistor described as "on" allows current to flow through it, while a transistor described as "off" prevents current from flowing through it.

[0021] Figure 1A An exemplary battery pack assembly for a vehicle system is depicted. Figure 1B The image depicts a battery pack assembly in which at least a portion of the outer casing is removed, exposing a battery pack comprising multiple stacked lithium-ion battery cells. The battery pack may be included in... Figure 2 In an exemplary vehicle battery system, the battery pack may be coupled to a BMS. The BMS may include protection circuitry, and its exemplary circuitry system is described in... Figure 3 The following is described. In some examples, the protection circuit can be configured to keep the BMS's disconnect circuit in an open state when no turn-on request is received. In additional or alternative examples, the protection circuit can be configured to keep at least one component of the disconnect circuit in an open state even when a turn-on request is received, thereby preventing current from flowing from one or more of the stacked lithium-ion battery cells to the electrical load. Therefore, in Figure 4 A method for managing current flow through a disconnected circuit is provided, which may include, for example, maintaining the disconnected circuit in an open state. Figure 5 The document provides exemplary operating sequences for a BMS used to manage the current flow through disconnecting and protecting circuits.

[0022] Now for reference Figure 1A A schematic diagram 100 depicting a battery pack assembly 102 is shown. The battery pack assembly 102 can be configured to start a vehicle (such as an electric vehicle or a hybrid electric vehicle) or to power a vehicle. For example, the battery pack assembly 102 may include a 48V battery pack comprising multiple lithium-ion battery cells (see reference below). Figure 1B (Detailed description)

[0023] Multiple lithium-ion battery cells can be arranged in a stacked configuration and removably enclosed within an outer housing 104. Therefore, the outer housing 104 can be constructed of a material with low electrical conductivity, such as plastic or other polymers, to reduce short-circuit events within the vehicle. The outer housing 104 (which...) Figure 1A The battery pack assembly 102 (described as a rectangular prism) can be molded into the vehicle with a clearance fit, allowing the battery pack assembly 102 to have surface-shared contact with one or more components of the vehicle, such as one or more engine components.

[0024] The outer housing 104 can be further configured to include openings or cavities for interface components of the battery pack assembly 102. For example, the outer housing 104 can be configured to expose the positive terminal 106 and the negative terminal 108, which may each be leadless terminals. That is, the positive terminal 106 and the negative terminal 108 can be insert-molded into appropriate locations on the outer housing 104. Within the vehicle, the positive terminal 106 and the negative terminal 108 can be electrically coupled to positive and negative leads, respectively, such that the battery pack assembly 102 can form a closed circuit with the vehicle's electrical loads, enabling power to be supplied to the vehicle.

[0025] The positive terminal 106 and the negative terminal 108 can be configured with different colors, shapes, symbols, etc., to indicate which terminal 106 or 108 is positive and which is negative. For example, the positive terminal 106 can be red and indicated by a plus sign (+), and the negative terminal 108 can be black and indicated by a minus sign (-). However, in some cases, the positive and negative leads may be incorrectly coupled, allowing the positive lead to couple to the negative terminal 108 and the negative lead to couple to the positive terminal 106. In this case, a reverse bias voltage may be applied due to the potential difference, and the battery assembly 102 may discharge unexpectedly without any protection. Therefore, and referring to the following... Figure 2 and Figure 3 The battery pack assembly 102 discussed may include a BMS with reverse bias protection circuitry, wherein the BMS can be coupled to multiple lithium-ion battery cells and an electrical load. In this way, the MOSFETs of the BMS can remain off during the application of a reverse bias voltage, thereby mitigating degradation of the individual battery cells and the BMS.

[0026] In some examples, the outer housing 104 may be configured to expose the network management interface 110. In one example, the network management interface 110 may be communicatively coupled to the vehicle's Local Interconnect Network (LIN) 112 via a wired or wireless connection. Therefore, in some examples, the network management interface 110 may include a physical connector for mating with a complementary connector fixed to wires extending from the LIN bus.

[0027] In some examples, the outer housing 104 may include a top cover 114a removably attached to the housing base 114b. Thus, the top cover 114a can be temporarily removed to replace or diagnose one or more of the multiple lithium-ion battery cells.

[0028] Now for reference Figure 1B A schematic diagram 150 depicting a battery pack 152 is shown. In some examples, the battery pack 152 may be included in... Figure 1A In the battery pack assembly 102, the top cover 114a has been removed from the battery pack assembly 102, thereby exposing a plurality of lithium-ion battery cells 154 removably fixed to the housing base 114b. Therefore, it should be understood that each lithium-ion battery cell 154 can represent a basic unit, thereby allowing the construction of battery packs of arbitrary size, arbitrary power, and with an arbitrary number of lithium-ion battery cells 154. It should also be understood that in Figure 1B Other embodiments not depicted may include a battery pack having only one lithium-ion battery cell.

[0029] In some examples, multiple lithium-ion battery cells 154 can be arranged in a stacked configuration, wherein each of the multiple lithium-ion battery cells 154 can be a prismatic bag electrochemical cell. Thus, each of the multiple lithium-ion battery cells 154 can include a positive electrode and a negative electrode immersed in a liquid electrolyte, wherein each of the positive electrode, the negative electrode, and the electrolyte can be sealed in an airtight bag.

[0030] Furthermore, each of the plurality of lithium-ion battery cells 154 may expose a positive electrode terminal 156 and a negative electrode terminal 158, which may be configured to be coupled to the positive electrode and the negative electrode, respectively. Therefore, each of the plurality of lithium-ion battery cells 154 may be electrically coupled to the above reference. Figure 1A The positive terminal 106 and negative terminal 108 are described in detail. In some examples, multiple lithium-ion battery cells 154 can be connected via one or more busbars ( Figure 1B (Not shown) are electrically coupled in series and / or in parallel, wherein one or more busbars can each be electrically coupled to multiple electrode terminals 156, 158 on multiple lithium-ion battery cells 154. One or more busbars can be further electrically coupled to one of the terminals 106, 108, such that multiple lithium-ion battery cells 154 can be electrically coupled to terminals 106, 108, thereby providing power to a system (e.g., a vehicle).

[0031] Each lithium-ion battery cell 154 of the battery pack 152 may be identical to each other. Furthermore, each of the total number of lithium-ion battery cells 154 and the electrical coupling configuration of the battery pack 152 (e.g., parallel counting and series counting) can define its electrical characteristics and performance ratings. As an example, the battery pack 152 may be configured in a '4S4P' configuration, having 16 lithium-ion battery cells 154 in four subgroups, wherein the subgroups may be electrically coupled in series, and wherein the four lithium-ion battery cells 154 in each subgroup may be electrically coupled in parallel. In some examples, the total number of lithium-ion battery cells 154 may be odd. In other examples, the total number of lithium-ion battery cells 154 may be even.

[0032] Multiple lithium-ion battery cells 154 can be held in a stacked configuration by bands 160. As shown, one or more bands 160 can surround multiple lithium-ion battery cells 154 to prevent the individual lithium-ion battery cells 154 from shifting relative to each other.

[0033] Now for reference Figure 2 This diagram illustrates a general block diagram 200 depicting a vehicle battery system 202. The vehicle battery system 202 may include a battery pack 204 (such as...). Figure 1BThe battery pack 204 includes one or more lithium-ion battery cells 222. As shown, the positive power line 252 couples the positive terminal of the battery pack 204 to an electrical load 206 (e.g., a belt-integrated starter generator, an integrated starter generator, etc.) via the BMS 208, and the ground loop 254 couples the electrical load 206 to the negative terminal of the battery pack 204. Specifically, the positive power line 252 of the battery pack 204 can be coupled to the input 256a of the cutoff circuit 210, and the output 256c of the cutoff circuit 210 can be coupled to the electrical load 206. Furthermore, the control input 256b of the cutoff circuit 210 can be coupled to the driver integrated circuit (IC) 212 of the BMS 208 via the protection circuit 214. Therefore, the driver IC 212 is communicatively coupled to the controller 272, which can store machine-readable instructions on a non-transitory storage device. These machine-readable instructions can be executed by the controller 272 to enable various functions of the BMS 208, such as receiving and transmitting switch requests, monitoring the vehicle battery system 202, etc. It should be understood that although the controller 272... Figure 2 The controller 272 is depicted as being included within the driver IC 212, but in other examples, the controller 272 may be located outside the driver IC 212. As further shown, the positive terminal 216 may be coupled to the line that couples the BMS 208 to the electrical load 206, and the negative terminal 218 may be coupled to the line that couples the electrical load 206 to the battery pack 204 (ground loop 254). [Alternatively, the positive terminal 216 and the negative terminal 218 may be connected via respective buses (…). Figure 2 [(not shown) coupled to BMS 208]. Therefore, it should be understood that the electrical load 206 can be located outside the battery pack 204.

[0034] The disconnect circuit 210 can be coupled to other components in the vehicle battery system 202 via input 256a, control input 256b, and output 256c. Therefore, the voltage at control input 256b relative to the voltage at output 256c can control the operating state of the disconnect circuit 210. For example, if the relative voltage across control input 256b and output 256c is less than a threshold operating voltage, the disconnect circuit 210 can be in an off state. Conversely, if the relative voltage across control input 256b and output 256c is greater than or equal to the threshold operating voltage, the disconnect circuit 210 can be in a conducting state. In this way, the disconnect circuit 210 can act as a switch to selectively allow current to flow from input 256a to output 256c depending on the voltage applied to control input 256b.

[0035] The cutoff circuit 210 may include one or more FETs, such as a MOSFET or JFET, other types of transistors, or combinations thereof. In some examples, the cutoff circuit 210 may be a single MOSFET, such as an n-channel enhancement-mode MOSFET, a p-channel enhancement-mode MOSFET, etc. In such an example, input 256a may be a drain terminal, control input 256b may be a gate terminal, and output 256c may be a source terminal. Therefore, as an exemplary embodiment, the operation of the cutoff circuit 210 may be described below as the operation of a MOSFET 210 having a drain terminal 256a, a gate terminal 256b, and a source terminal 256c.

[0036] Specifically, the MOSFET 210 can operate at zero gate-source voltage (V GS The MOSFET 210 is in the off state at the current position. Therefore, switching the MOSFET 210 to the on state may depend on the voltage (V) at the gate terminal 256b. G ) relative to the voltage at source terminal 256c (V S ), that is, V GS If V GS V higher than MOSFET 210 th Then, MOSFET 210 can switch from the off state to the on state. When in the on state, MOSFET 210 allows current to flow from the drain terminal 256a to the source terminal 256c. Conversely, when in the off state, MOSFET 210 prevents current from flowing through it.

[0037] During battery operation, the driver IC 212 can receive an on request and can output V. GS (greater than V) th The driver IC 212 switches MOSFET 210 to the on state. However, in some cases, MOSFET 210 may unexpectedly switch from the off state to the on state without any feedback from the driver IC 212. For example, a higher current or short-circuit voltage distribution may be generated by reverse polarity events, negative electrical noise in the vehicle battery system 202, etc.

[0038] Specifically, the unexpected switching of MOSFET 210 may originate from any event that produces a significantly negative Vt. S The incident, because of negative V S It may lead to a positive V GS As implied by equation (1):

[0039] V GS =V G –V S (1)

[0040] As an example only, if V G zero and V S If it is negative, then V GS It is a positive value, and if V GS The positive value is greater than V th Then MOSFET 210 can be turned on.

[0041] Therefore, this document provides a protection circuit for maintaining a MOSFET in an off state during unexpected voltage spikes in a vehicle battery system. For example, protection circuit 214 can be included in BMS 208 to protect MOSFET 210 from accidental turn-on by dissipating energy accumulated in vehicle battery system 202 during short-circuit or high-current conditions. Thus, protection circuit 214 can maintain V G and V S The gate terminal 256b and source terminal 256c of MOSFET 210 are controlled to be close to zero or essentially zero, so that V GS The amplitude can be maintained at a low value and not exceed V. th (“basically” can be used as a qualifier for “effectively” in this text.)

[0042] For circuits that do not include the reverse bias protection circuit described herein, the current at the charge pump included in the driver IC 212 may discharge to compensate for leakage current at MOSFET 210 during reverse bias conditions. Therefore, the vehicle battery system 202 may lose the accumulated charge at the charge pump, causing the driver IC 212 to be unable to effectively supply current to various parts of the vehicle battery system 202 (e.g., failing to turn on MOSFET 210 when an actual turn-on request is received). Consequently, a sudden negative Vt is generated at MOSFET 210. S At that time, the current drawn from the charge pump may deteriorate undesirably.

[0043] Conversely, in this disclosure, once negative V is detected... S Above the threshold V S The protection circuit 214 prevents the charge pump from discharging. See below for details. Figure 3 As discussed in detail, a current path can be provided in the protection circuit 214 via a pair of series diodes to allow current to flow to the gate terminal 256b of the MOSFET 210.

[0044] In order to maintain V GS Less than V th The protection circuit 214 may further include a switchable current path disposed between the gate terminal 256b and the source terminal 256c. The switchable current path may include a transistor or switching device, such as a BJT, which can respond to the detection of an unexpected negative VS While maintaining a lower V at MOSFET 210 GS This keeps MOSFET 210 in the off state. Therefore, by reducing current consumption at the charge pump and preventing MOSFET 210 from turning on without any turn-on request, protection circuit 214 can mitigate the degradation of one or more lithium-ion battery cells 220 in BMS 208 and battery pack 204, thereby allowing BMS 208 to continue its intended functions, such as protecting battery pack 204 from deep discharge.

[0045] In this way, BMS 208 can be configured to allow current to flow through the switchable current path of protection circuit 214 when a reverse bias voltage is detected at the output 256c of cutoff circuit 210 (e.g., at the source terminal 256c of MOSFET 210). BMS 208 can also be configured to prevent current from flowing through the switchable current path in response to the absence of a reverse bias voltage at the output 256c of cutoff circuit 210 (e.g., at the source terminal 256c of MOSFET 210).

[0046] It should be understood that, despite Figure 2 The diagram depicts a single MOSFET 210, but the BMS 208 may include an array of MOSFETs. Therefore, aspects of this disclosure can be applied to each MOSFET in the MOSFET array, enabling protection of each MOSFET in the MOSFET array from accidental turn-on.

[0047] Now for reference Figure 3 A schematic diagram 300 of a circuit system is shown, depicting an example of a reverse bias protection circuit 314 (also referred to herein as protection circuit 314) included in a BMS 308. In some examples, reference is made to... Figure 3 One or more components described can be replaced by the above reference. Figure 2 The vehicle battery system 202 is described. For example... Figure 2 BMS208 and Figure 3 The BMS 308 can be the same or an equivalent circuit. Figure 3 The component numbers in the circuit are combined with them Figure 3 Consistent with the above.

[0048] like Figure 3As shown, BMS 308 may also include a cutoff circuit 310 (e.g., a MOSFET or other known transistor) and a driver IC 312, each coupled to a protection circuit 314. MOSFET 310 may include a drain terminal 356a (input), a gate terminal 356b (control input, which controls the operating state of MOSFET 310), and a source terminal 356c (output). The drain terminal or input 356a may be directly coupled to the battery pack via a positive power line 352. Figure 3 The positive terminal (not shown). The gate terminal or control input 356b can be coupled to the driver IC 312 via protection circuit 314. The source terminal or output 356c can be directly coupled to protection circuit 314. The source terminal 356c can also be directly coupled to the positive battery output terminal 316, and terminal 316 is directly coupled to the (external) electrical load 306. The electrical load 306 can also be directly coupled to the negative battery output terminal of the battery pack via ground loop 354. It should be understood that the electrical load 306 can be located outside the battery pack (i.e., the electrical load 306 may not be part of the battery pack). As further shown, various connections of two or more electrical conductors or wires can be represented by nodes 370a, 370b, 370c, 370d, 370e, 370f, 370g, 370h, 370i, 370j, and 370k, respectively. As described below, the dashed directional arrow 382 depicts an exemplary current flow during the expected turn-on period of MOSFET 310 in normal circuit operation. That is, directional arrow 382 depicts an exemplary current flow when MOSFET 310 is in the on state and the low-leakage-current transistor 358 of protection circuit 314 is in the off state, in the absence of reverse bias at terminal 316.

[0049] MOSFET 310 may also include a body diode 356d. In some cases, such as during a reverse polarity event or when significant negative noise has accumulated in the battery system and protection circuit 314 is absent, a reverse bias can be applied across the body diode 356d when MOSFET 310 is in the off state. The body diode 356d can then be triggered, thereby accidentally switching MOSFET 310 from the off state to the on state.

[0050] During such events, when a reverse bias voltage is applied and the protection circuit 314 is absent, a high current distribution may form in the battery system. Consequently, a significant amount of energy may accumulate, and this accumulated energy can be dissipated through the weakest (i.e., least resistive) path in the battery system. For example, without the protection circuit 314, the high current may reach ground through the body diode 356d, thus overloading the MOSFET 310. Therefore, the protection circuit 314 is provided herein to control this high current. This is discussed in detail below and referenced above. Figure 2 As illustrated, the protection circuit 314 can reduce the voltage of MOSFET 310 by... G and V S Each of these components is maintained near or substantially at 0 V to protect MOSFET 310 from reverse bias voltage. Therefore, dashed directional arrow 384 depicts an exemplary current flow during reverse bias voltage conditions, where current can be redirected through protection circuitry 314, as described below. That is, directional arrow 384 depicts an exemplary current flow when MOSFET 310 is off and the low-leakage-current transistor 358 of protection circuitry 314 is on. Thus, the current path is shown to begin at ground 366, and it passes through diodes 364a and 364b, through resistors 362a and 362b, through diode 364d, through resistor 362c, through transistor 358, through node 370e, and terminates at electrical load 306.

[0051] As shown in the figure, the driver IC 312 can be configured with three pins 368a, 368b, and 368c to change the timing of its output. Specifically, pin 368a can be used to turn on MOSFET 310, pin 368b can be used to turn off MOSFET 310, and pin 368c can be used as a V signal to control MOSFET 310. GS The reference pin is 368a. Therefore, pin 368a can provide a voltage (e.g., 5 V) that can be supplied to the gate terminal 356b of MOSFET 310 to turn on MOSFET 310. Pin 368b can supply V... G Pulled to ground, and pin 368c can be coupled to the source terminal 356c of MOSFET 310 to reference V. S In some examples, the switching mechanism of pin 368a may be slower than that of pin 368b. That is, the resistance of resistor 362a coupled between pin 368a and MOSFET 310 may be higher than the resistance of resistor 362b coupled between pin 368b and MOSFET 310.

[0052] Without the protection circuit 314, when a significant negative V is applied...S At that time, V GS It can be increased to a voltage higher than that of MOSFET310. th The positive value. However, the protection circuit 314 can change V by... G and V S Maintaining a voltage close to or substantially at 0 V protects MOSFET 310, thereby keeping MOSFET 310 in an off state. Two key features of the protection circuit 314 are provided to protect various components of BMS 308, and thus various components of the entire battery system: diodes 364a, 364b, and 364f to feed current from ground 366, and a low-leakage-current transistor 358 to reduce the voltage of MOSFET 310 to near or substantially 0 V. GS Maintain at V th The following (as shown by directional arrow 384).

[0053] For example, when a reverse bias voltage is applied, diode 364f can prevent excessive current from being drawn from pin 368c to the source terminal 356c of MOSFET 310 via resistor 362g coupled between pin 368c and the source terminal 356c of MOSFET 310. Specifically, current can alternatively be fed from ground 366 via diode 364f, as indicated by directional arrow 384. As shown, in some examples, diode 364f can be a Schottky diode because Schottky diodes can have a relatively low forward voltage drop, allowing diode 364f to be closer to ground 366. Furthermore, configuring diode 364f in the direction shown can prevent current from flowing back to ground 366 when MOSFET 310 is controllably switched on. Additionally, resistors 362f and 362g can be connected in parallel to limit the current from pin 368c, thereby preventing current from flowing back to ground 366 when a negative V is detected. S The voltage at pin 368c is maintained close to zero and is kept close to a reference value during the expected battery operation. When MOSFET 310 is off, current can continue to flow to electrical load 306 through terminal 316 due to the inductive characteristic of electrical load 306. Therefore, node 370j can have a negative voltage. To maintain current flow to electrical load 306 and prevent current from being drawn from pin 368c, diode 364f and node 370i are provided to form a new circuit path to supply current to electrical load 306.

[0054] Similarly, and further as shown in the figure, diodes 364a and 364b can be coupled in series to prevent excessive current from being drawn from the charge pump to the gate terminal via pin 368a and resistor 362a between the charge pump 320 coupled within the driver IC 312 and the gate terminal 356b of the MOSFET 310. Specifically, when an unexpected negative V is detected... SIn this case, current can alternatively be fed from ground 366 via diodes 364a and 364b, as indicated by directional arrow 384. Therefore, diodes 364a and 364b can be low-leakage-current diodes, thus providing low leakage current during unexpected battery operation. In this way, the controllability of the driver IC 312 and consequently the BMS 308 over the battery system can be protected. Furthermore, when the charge pump 320 supplies current in response to a turn-on request at the driver IC 312, configuring diodes 364a and 364b in the orientation shown can prevent current from flowing back to ground 366, as indicated by directional arrow 382.

[0055] In some examples, and further illustrated in the figure, the driver IC 312 is communicatively coupled to the controller 372, which can store machine-readable instructions on a non-transitory storage device. These machine-readable instructions can be executed by the controller 372 to enable various functionalities of the BMS 308, such as receiving and transmitting switch requests, monitoring the battery system, etc. It should be understood that although the controller 372... Figure 3 It is depicted as being included within the driver IC 312, but in other examples, the controller 372 may be located outside the driver IC 312.

[0056] When a reverse bias voltage (i.e., negative V) is detected at the source terminal 356c of MOSFET 310 S When the current is generated, it can be fed from ground 366 to node 370f and low-leakage-current transistor 358 through diode 364f (e.g., via resistor 362f). In some examples, diode 364e can be a Zener diode or a transient-voltage suppression (TVS) diode, such that diode 364e can clamp the voltage across it to a set value, such as 8.5 V.

[0057] In some examples, the low-leakage-current transistor 358 may be a BJT, which includes an input (e.g., collector) terminal 360a, a control input (e.g., base) terminal 360b, and an output (e.g., emitter) terminal 360c. A voltage V relative to the source voltage V can be generated at node 370f via diode 364e. S A voltage of approximately 8.5 volts, which can be reduced via a voltage divider formed by resistors 362e and 362d, allows current to flow into base terminal 360b, thereby switching transistor 358 from the off state to the on state.

[0058] As shown in the figure, the anode of diode 364e can be coupled to the emitter terminal 360c, and the cathode of diode 364e can be directly coupled to node 370f. Therefore, the anode of diode 364e can have a higher voltage than the emitter terminal 360c, and diode 364e can be used to stabilize the base-emitter voltage (V) of low-leakage-current transistor 358. BE ).

[0059] Therefore, when a negative V is unexpectedly generated S At that time, the low leakage current transistor 358 can pass through negative V S Connect, thereby increasing its V BE Therefore, the low-leakage-current transistor 358 can be considered as a switch that allows current to flow from diodes 364a and 364b to the source terminal 356c, as indicated by directional arrow 384. Current can flow through resistor 362a to resistor 362b, then to diode 364d, then to resistor 362c, then through transistor 358, and finally to node 370k, which is directly coupled to the source terminal 356c. The current allows V... G Approaching V S This prevents MOSFET 310 from being turned on.

[0060] Specifically, once the low-leakage-current transistor 358 is turned on, the V of MOSFET 310... G This can be quickly pulled down to the emitter voltage (V) of the low-leakage-current transistor 358. E Since the emitter terminal 360c can be coupled to the source terminal 356c of the MOSFET 310, the V of the MOSFET 310... GS V can be transmitted through the low leakage current transistor 358 CE To maintain this. Therefore, when the V at both ends of the collector terminal 360a and the emitter terminal 360c... CE When it drops to, for example, less than 1 V, V GS It can be maintained at less than V th The value is set, and MOSFET 310 can remain in the off state.

[0061] On the other hand, during the expected battery operation period, the low-leakage-current transistor 358 can be turned off, and pin 368a can supply voltage to increase the V of MOSFET 310. GThe MOSFET 310 is turned on. When the MOSFET 310 is on, current can flow from the drain terminal 356a to the source terminal 356c and then to the electrical load 306. The MOSFET 310 can be turned off via pin 368b. When the MOSFET 310 is switched on, current can be prevented from flowing from the drain terminal 356a to the source terminal 356c. In this way, a switchable current path, including a low-drain-current transistor 358, can be electrically coupled to the MOSFET 310, the switchable current path being arranged between the gate terminal 356b and the source terminal 356c of the MOSFET 310.

[0062] In some examples, diodes 364c and 364d can be further provided as choke diodes to maintain the direction of current flow via pin 368b to driver IC 312 and via resistor 362c to low-leakage-current transistor 358, respectively. Therefore, and as shown, when MOSFET 310 is controllably turned off, diode 364c can be oriented in the desired direction of current flow via pin 368b to driver IC 312, and diode 364d can be oriented in the desired direction of current flow via resistor 362c to low-leakage-current transistor 358 to protect MOSFET 310 from unintended reverse bias voltages delivered to source terminal 356c. In one example, each of diodes 364c and 364d can be a diode with a relatively low forward voltage drop, such as a Schottky diode.

[0063] In this way, the current can respond to the negative V. S A current is applied to node 370e, causing current to flow from nodes 370b and 370c coupled to the gate terminal 356b of MOSFET 310 to nodes 370d and 370e coupled to the source terminal 356c of MOSFET 310, while current flowing across the gate terminal 356b to the source terminal 356c is blocked. Therefore, a negative voltage at the source terminal 356c can prevent MOSFET 310 from turning on. This current can be achieved by activating a low-leakage-current transistor 358 positioned between nodes 370b and 370c and nodes 370d and 370e. In some examples, current can flow from ground 366 through diodes 364a and 364b to nodes 370b and 370c. However, in response to no negative voltage applied to node 370e... S Current may not be able to flow from nodes 370b and 370c to nodes 370d and 370e. As indicated by directional arrows 382 and 384, in response to negative V SWhen applied to node 370e, current can travel along line 394 through each of terminal 316 and electrical load 306 to ground loop 354, regardless of whether MOSFET 310 is on or off.

[0064] In some examples, even if an enable request is received, the circuitry depicted in schematic 300 can be implemented in the vehicle battery system to prevent MOSFET 310 from being turned on. As an example, MOSFET 310 can be one of a plurality of MOSFETs arranged in an array. One of the MOSFETs 310 can be electrically coupled to one of a plurality of lithium-ion battery cells in the battery pack. In some examples, when an enable request is received, a portion of the lithium-ion battery cells can be used to supply power to the vehicle battery system, and the remainder can be kept off by protection circuitry 314.

[0065] Now for reference Figure 4 The diagram illustrates a flowchart depicting a method 400 for providing reverse bias protection to the battery. Reverse bias protection can be achieved via... Figure 2 and Figure 3 The circuit system shown is provided. Typically, during the application of a reverse bias voltage in a vehicle battery system, the cutoff circuit may be at risk of accidental turn-on, such as due to an unexpected reverse polarity event or accumulated negative noise. In the specific example where the cutoff circuit is a MOSFET, if the MOSFET's V... GS Increase V to MOSFET th The above (e.g., via a sufficiently negative V) S If this occurs, the MOSFET may be accidentally turned on, potentially discharging and degrading the vehicle's battery system.

[0066] The following is about Figures 1A to 3 The system and components described herein illustrate method 400. For example, in some examples, method 400 can be... Figure 2 BMS 208 or Figure 3 The method 400 is implemented in BMS 308. In such an example, a step or a portion thereof of method 400 may represent an action taken in the physical world via a hardware device, such as BMS 208 or one or more components of BMS 308. It should be understood that method 400 may be implemented with other systems and components without departing from the scope of this disclosure. It should also be understood that the various steps discussed with reference to method 400 may be added, removed, replaced, or interchanged within the scope of this disclosure.

[0067] Method 400 can begin with Figure 4At 402, method 400 may include responding to the detection of a reverse bias voltage at the positive battery terminal or to an unexpected turn-on of the cut-off circuit. If no reverse bias voltage or unexpected turn-on is detected, the desired battery operation can proceed. Specifically, method 400 may proceed to 404, where method 400 may include determining whether a turn-on request is received at the driver IC or at a controller coupled to the driver IC. Specifically, the turn-on request may be a command for switching the cut-off circuit of the BMS from an off state to an on state. If no turn-on request is received, method 400 may return to 402.

[0068] If a power-on request is received, method 400 may proceed to 406, where method 400 may include powering on the battery pack to supply power to the vehicle by activating the BMS's disconnect circuit and closing the vehicle battery system's battery circuit. Specifically, the positive power line can supply power from the battery pack to the vehicle's (external) electrical loads. However, it should be understood that even if a power-on request is received, for example when negative electrical noise accumulates in the vehicle battery system, the reverse bias protection circuit can mitigate the degradation of the vehicle battery system. Method 400 may then terminate.

[0069] Returning to 402, if a reverse bias voltage or accidental connection is detected, battery operation protection can be implemented. Specifically, the reverse bias protection circuit prevents the disconnect circuit from coupling the battery cell to an electrical load, thereby mitigating the degradation of the vehicle's battery system.

[0070] Method 400 can proceed to 408, wherein method 400 may include feeding current (e.g., current from ground) to the output of the cutoff circuit via a low-leakage-current transistor in a reverse-biased protection circuit. In some examples, the low-leakage-current transistor may be a BJT, and the cutoff circuit may be a MOSFET, such that its collector terminal can be coupled to the gate terminal (control input) of the MOSFET and its emitter terminal can be coupled to the source terminal (output) of the MOSFET. The emitter terminal of the low-leakage-current transistor may be further coupled to the anode of a Zener diode, and the base terminal of the low-leakage-current transistor may be coupled to the cathode of the Zener diode. In other examples, a TVS diode may be used.

[0071] At 410, method 400 may include increasing the V of the low-leakage-current transistor via a Zener diode. BE This allows the low-leakage-current transistor to be switched on. Furthermore, by coupling the cathode and anode of the Zener diode to the base and emitter terminals of the low-leakage-current transistor, respectively, V can be switched on. BE Clamp to a set value, such as less than 8.5 V.

[0072] At 412, method 400 may include reducing the V of the low-leakage-current transistor. CE This keeps the circuit open. Specifically, once the low-leakage-current transistor is turned on, the voltage across the collector and emitter terminals (i.e., V) is maintained. CE The voltage level may drop to a low value and remain low, for example, less than 1 V. Therefore, by coupling the control input of the cutoff circuit to the collector terminal of the low-leakage-current transistor and the output of the cutoff circuit to the emitter terminal of the low-leakage-current transistor, the voltage difference between the control input and the output of the cutoff circuit can be maintained accordingly. In the example where the cutoff circuit is a MOSFET, the gate terminal of the MOSFET can be coupled to the collector terminal of the low-leakage-current transistor, and the source terminal of the MOSFET can be coupled to the emitter terminal of the low-leakage-current transistor. V GS This can be maintained by activating a transistor. In this way, V GS It can be maintained at the V of the MOSFET th The following allows the MOSFET to remain in the off state. Method 400 can then return to 402.

[0073] Now for reference Figure 5 , showing the depiction Figures 1A to 3 The timeline 500 shows two exemplary operating sequences of a vehicle battery system. Specifically, the vehicle battery system may be configured with one or more disconnect circuits, such as one or more MOSFETs, coupled to one or more protection circuits. A given disconnect circuit may be turned on in response to a turn-on request received by the vehicle battery system, which may allow current to flow through the given disconnect circuit to power the vehicle in which the vehicle battery system may be implemented. However, in some examples, the given disconnect circuit may be in an off state when a reverse bias voltage is applied to the output of the given disconnect circuit. In such examples, the protection circuit coupled to the given disconnect circuit may include a low-leakage-current transistor, such as a bipolar junction transistor (BJT). When turned on, the low-leakage-current transistor may be configured to maintain the voltage applied across the control input and output of the given disconnect circuit so that the given disconnect circuit is not accidentally turned on. In this way, the protection circuit can mitigate the degradation of the vehicle battery system by reducing the likelihood of accidental activation of the disconnect circuit system. In some examples, the vehicle battery system may include the components described above, respectively referenced in the references. Figure 2 and Figure 3 The BMS 208 or BMS 308 described.

[0074] Timeline 500 depicts the cut-off circuit state at solid curves 501 and 503, the voltage applied to the output (e.g., source) of the cut-off circuit at solid curves 511 and 513, the voltage difference between the control input and output of the cut-off circuit at solid curves 521 and 523, the low-leakage-current transistor state at solid curves 531 and 533, and the VL of the low-leakage-current transistor at solid curves 541 and 543. BE Furthermore, the Vo of the low-leakage-current transistor is depicted at solid curves 551 and 553. CE Additionally, dashed curves 522 and 524 represent the first threshold voltage applied across the control input and output, at which point the cutoff circuit state can switch between an off state and a on state. It should be understood that when the cutoff circuit includes a MOSFET, the voltage applied to the output (curves 511 and 513) can be the MOSFET's Vt. S The voltage difference between the control input and output terminals (curves 521 and 523) can be controlled by the V of the MOSFET. GS And the first threshold voltage (curves 522 and 524) can be the V of the MOSFET. th .

[0075] All curves are plotted over time and along the x-axis, where time increases from left to right on the x-axis. Furthermore, the dependent variable represented by each curve discussed above is plotted along the corresponding y-axis, where the dependent variable increases from the bottom to the top of the given y-axis (unless otherwise stated or shown).

[0076] At t1, the first exemplary operating sequence of the vehicle battery system can begin. Between t1 and t2, each of the cut-off circuit state (curve 501) and the low-leakage-current transistor state (curve 531) can be in an off state. At t2, for example, a negative voltage can be detected at the output of the cut-off circuit (curve 511) due to a reverse bias voltage condition. In response to the detection of a negative voltage at the output, current can be redirected to the Zener diode (or TVS diode) coupled to the low-leakage-current transistor.

[0077] At t3, the low-leakage-current transistor can switch from the off state to the on state (curve 531). Current can therefore flow through the low-leakage-current transistor instead of the cut-off circuit because the low-leakage-current transistor can couple to a current path with lower resistance than the cut-off circuit.

[0078] Therefore, after t3, V CE It can decrease significantly from the first value to the second value, and then remain at the second value (curve 551). For example, V CE It can be reduced from about 12 V to less than 1 V (e.g., close to or essentially equal to 0 V) ​​and then maintained at that level. Furthermore, VBE It may increase and plateau at values ​​smaller than those clamped by the Zener diode (curve 541). For example, V BE This can be increased to approximately 0.7 V. Furthermore, in the vehicle battery system corresponding to the illustrated example, the control input of the cut-off circuit can be coupled to the collector terminal of the low-leakage-current transistor, and the output of the cut-off circuit can be coupled to the emitter terminal of the low-leakage-current transistor. Therefore, the voltage difference between the control input and output can be maintained (curve 521), for example, less than a first threshold voltage (curve 522). For example, the voltage difference between the control input and output can be maintained accordingly at less than 1 V (e.g., close to or substantially 0 V). In this way, the protection circuit can prevent the voltage difference between the control input and output from reaching the first threshold voltage, allowing the cut-off circuit to remain in the off state (curve 501). The extended time interval between t3 and t4 is indicated by the interruption on the horizontal axis, during which the cause of the negative voltage at the output of the cut-off circuit (such as the reverse bias voltage condition) can end.

[0079] At t4, the second exemplary operating sequence of the vehicle battery system can begin. Therefore, between t4 and t5, each of the cut-off circuit state (curve 503) and the low leakage current transistor state (curve 533) can be in the off state.

[0080] At t5, the vehicle battery system can receive a request to turn on the cut-off circuit and can apply voltage to the control input of the cut-off circuit. Therefore, between t5 and t6, the voltage difference between the control input and the output of the cut-off circuit may increase (curve 523) until a first threshold voltage is reached at t6 (curve 524) and the cut-off circuit switches from the off state to the on state. The voltage difference between the control input and the output may continue to increase to a constant voltage value. Accordingly, after t6, the voltage applied to the output of the cut-off circuit can increase to a constant (positive) voltage value (curve 513).

[0081] During the second exemplary operation sequence, the V of the low leakage current transistor BE and V CE Each of them is maintained at a constant voltage value close to or substantially at 0 V (curves 543 and 553, respectively). Therefore, during the second exemplary operating sequence, V BE The second threshold voltage was not reached (curve 544), and the low leakage current transistor remained off (curve 533). In this way, in some examples, the protection circuit can be activated without responding to a request to turn on the disconnect circuit received by the vehicle battery system.

[0082] In this manner, a vehicle battery system is provided, comprising a battery pack coupled to a battery management system (BMS), wherein the BMS may include reverse bias protection circuitry to maintain a cutoff circuit in an off state during the application of a reverse bias voltage. In some examples, the cutoff circuitry may include a metal-oxide-semiconductor field-effect transistor (MOSFET). Specifically, the gate-source voltage (Vo) of the MOSFET remains constant unless a turn-on request is received at the BMS. GS It can be maintained at the threshold voltage (V) th Below. In some examples, the MOSFET can be coupled to a low-leakage-current transistor, such as a bipolar junction transistor, such that the V0 of the MOSFET... GS It can be determined by the collector-emitter voltage (V) of a low-leakage-current transistor. CE This is maintained by coupling the MOSFET to the reverse bias protection circuit in this way. The technical advantage of this method is that the MOSFET can be protected during reverse bias voltage conditions, thereby protecting the entire vehicle battery system from degradation. Furthermore, the reverse bias protection circuit can be implemented without expensive components such as additional MOSFETs or highly complex control circuitry.

[0083] In one example, a vehicle battery system includes: a battery management system including a MOSFET; a battery pack having a plurality of stacked battery cells, the positive power line of the battery pack being coupled to the MOSFET; and a reverse bias protection circuit coupled to the MOSFET, the reverse bias protection circuit including a low leakage current transistor configured to reduce the gate-source voltage (Vo) of the MOSFET. GS Maintain the threshold voltage (V) of the MOSFET. th )the following.

[0084] In another example, a vehicle battery system includes: a battery management system (BMS) including a disconnect circuit electrically coupled to a reverse bias protection circuit; and a battery pack having a plurality of stacked battery cells, the positive power line of the battery pack being electrically coupled to the disconnect circuit, and wherein the reverse bias protection circuit includes each of an input to a control input electrically coupled to the disconnect circuit, an output electrically coupled to an output of the disconnect circuit, and a control input electrically coupled to the output of the disconnect circuit. A first example of the vehicle battery system further includes wherein the input, output, and control input of the reverse bias protection circuit are included in a switchable current path of the reverse bias protection circuit, the switchable current path being arranged between the control input and the output of the disconnect circuit. A second example of the vehicle battery system (optionally including the first example of the vehicle battery system) further includes wherein the BMS is configured to allow current to flow through the switchable current path when a reverse bias voltage is detected at the output of the disconnect circuit, and wherein the BMS is further configured to prevent current from flowing through the switchable current path in response to the absence of the reverse bias voltage at the output of the disconnect circuit. A third example of the vehicle battery system (optionally including one or more of the first and second examples of the vehicle battery system) further includes the reverse bias protection circuit comprising one or more diodes configured to feed current to the switchable current path upon detection of the reverse bias voltage. A fourth example of the vehicle battery system (optionally including one or more of the first to third examples of the vehicle battery system) further includes the input of the reverse bias protection circuit, the output of the reverse bias protection circuit, and the control input of the reverse bias protection circuit comprising a low leakage current transistor coupled to a Zener diode, the Zener diode being configured to increase the base-emitter voltage (V0) of the low leakage current transistor. BE The fifth example of the vehicle battery system (optionally including one or more of the first to fourth examples of the vehicle battery system) further includes the low leakage current transistor and the cut-off circuit configured such that when the low leakage current transistor is turned on, the collector-emitter voltage (V) of the low leakage current transistor is turned on. CE The voltage across the control input and output of the cut-off circuit is reduced. A sixth example of the vehicle battery system (optionally including one or more of the first to fifth examples of the vehicle battery system) further includes a low-leakage-current transistor whose V0 is reduced when the low-leakage-current transistor is turned on. CEThe voltage is reduced to and maintained below 1 V. A seventh example of the vehicle battery system (optionally including one or more of the first to sixth examples of the vehicle battery system) further includes wherein the BMS includes a driver integrated circuit electrically coupled to the reverse bias protection circuit via three pins. An eighth example of the vehicle battery system (optionally including one or more of the first to seventh examples of the vehicle battery system) further includes wherein the three pins include: a first pin configured to switch the cutoff circuit to an on state; a second pin configured to switch the cutoff circuit to an off state; and a third pin configured as a reference pin for controlling the voltage at the control input and output of the cutoff circuit.

[0085] In yet another example, a battery management system includes: a protection circuit including a low-leakage-current junction transistor; and a MOSFET including a drain terminal, a gate terminal, and a source terminal, the drain terminal being directly coupled to a positive power line of a battery pack having multiple battery cells, the source terminal being directly coupled to an electrical load and each of the low-leakage-current junction transistor, and the gate terminal being coupled to the low-leakage-current junction transistor, wherein the protection circuit is configured to maintain the MOSFET in an off state in response to a reverse bias voltage applied to the source terminal. A first example of the battery management system further includes wherein the low-leakage-current junction transistor includes a collector terminal, a base terminal, and an emitter terminal, wherein the collector terminal of the low-leakage-current junction transistor is coupled to the gate terminal of the MOSFET via each of a first resistor and a first diode, and wherein the emitter terminal of the low-leakage-current junction transistor is directly coupled to the source terminal of the MOSFET. A second example of the battery management system (optionally including a first example of the battery management system) further includes the protection circuit comprising a second diode, wherein the second diode is a Zener diode, wherein the emitter terminal is further coupled to the anode of the second diode, wherein the base terminal is coupled to the cathode of the second diode via a second resistor, and wherein the second diode is configured to respond to the reverse bias voltage applied to the source terminal by increasing the base-emitter voltage (V0) of the low-leakage-current junction transistor. BEThe first diode is coupled to the collector terminal to switch the low-leakage current junction transistor to its on state. A third example of the battery management system (optionally including one or more of the first and second examples of the battery management system) further includes wherein the first diode is coupled to the collector terminal to maintain the current direction flowing to the low-leakage current junction transistor in response to the reverse bias voltage applied to the source terminal. A fourth example of the battery management system (optionally including one or more of the first to third examples of the battery management system) further includes wherein maintaining the MOSFET in its off state includes reducing and maintaining the collector-emitter voltage (V0) of the low-leakage current junction transistor. CE The MOSFET maintains its gate-source voltage (V) accordingly. GS () lower than the threshold voltage (V) of the MOSFET th Furthermore, it remains in its disconnected state. A fifth example of the battery management system (optionally including one or more of the first to fourth examples of the battery management system) also includes a method for reducing and maintaining the V0 of the low-leakage-current junction transistor. CE Including the V CE Reduce to below 1 V and the V CE The voltage is maintained below 1 V. A sixth example of the battery management system (optionally including one or more of the first to fifth examples of the battery management system) further includes a driver integrated circuit coupled to the protection circuit, wherein the driver integrated circuit is configured to switch the MOSFET to its on state in response to receiving an on request generated via a controller coupled to the driver integrated circuit. A seventh example of the battery management system (optionally including one or more of the first to sixth examples of the battery management system) further includes wherein the driver integrated circuit includes a first output, a second output, and a third output, wherein the first output is configured to pull up the voltage (V) at the gate terminal. G The second output is configured to convert the V G Pulled to ground, and the third output is configured to regulate the voltage (V) of the source terminal. S An eighth example of the battery management system (optionally including one or more of the first to seventh examples of the battery management system) further includes two diodes coupled to a first output of the driver integrated circuit to feed current to the gate terminal in response to the reverse bias voltage applied to the source terminal. A ninth example of the battery management system (optionally including one or more of the first to eighth examples of the battery management system) further includes a diode coupled to a second output of the driver integrated circuit to feed current to the gate terminal in response to the V GWhen pulled to ground, the direction of current flow to the driver integrated circuit is maintained. A tenth example of the battery management system (optionally including one or more of the first to ninth examples of the battery management system) also includes a diode coupled to a third output of the driver integrated circuit to feed current to the source terminal in response to the reverse bias voltage applied to the source terminal.

[0086] In yet another example, a method for managing current flow through a battery pack cutoff circuit includes allowing current to flow from a first node coupled to a control input of the battery pack cutoff circuit to a second node coupled to an output of the battery pack cutoff circuit, while preventing current from flowing through the control input to the output in response to a negative voltage being applied to the second node. A first example of the method further includes preventing the current from flowing from the first node to the second node in response to the absence of the negative voltage at the second node. A second example of the method (optionally including the first example) further includes wherein the current flows from the first node to the second node by activating a transistor. A third example of the method (optionally including one or more of the first and second examples) further includes wherein the current flows from ground to the transistor by flowing through two diodes.

[0087] The following claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may relate to an “a” element or a “first” element or its equivalent. Such claims should be understood to include the introduction of one or more such elements, thus neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are considered to be included within the subject matter of this disclosure.

Claims

1. A vehicle battery system comprising: A battery management system (BMS) includes: a cutoff circuit electrically coupled to a reverse bias protection circuit; and a driver integrated circuit, wherein the driver integrated circuit is electrically coupled to the reverse bias protection circuit via three pins; and The battery pack has multiple stacked battery cells, and the positive power line of the battery pack is electrically coupled to the disconnect circuit. The reverse bias protection circuit includes each of an input electrically coupled to a control input of the cut-off circuit, an output electrically coupled to an output of the cut-off circuit, and a control input electrically coupled to the output of the cut-off circuit.

2. The vehicle battery system of claim 1, wherein the input, output, and control input of the reverse bias protection circuit are included in a switchable current path of the reverse bias protection circuit, the switchable current path being arranged between the control input and the output of the cut-off circuit.

3. The vehicle battery system of claim 2, wherein the BMS is configured to allow current to flow through the switchable current path when a reverse bias voltage is detected at the output of the disconnect circuit, and The BMS is further configured to prevent current from flowing through the switchable current path in response to the absence of the reverse bias voltage at the output of the cut-off circuit. Optionally, the reverse bias protection circuit includes one or more diodes configured to feed current into the switchable current path when the reverse bias voltage is detected.

4. The vehicle battery system according to any one of the preceding claims, wherein the input, the output, and the control input of the reverse bias protection circuit are included in a low leakage current transistor coupled to a Zener diode, the Zener diode being configured to increase the base-emitter voltage V of the low leakage current transistor. BE To turn on the low leakage current transistor.

5. The vehicle battery system of claim 4, wherein the low-leakage current transistor and the cut-off circuit are configured such that when the low-leakage current transistor is turned on, the collector-emitter voltage V of the low-leakage current transistor is... CE Reduce the voltage across the control input and the output of the cut-off circuit. Optionally, wherein when the low-leakage current transistor is turned on, the V of the low-leakage current transistor... CE Reduce to and maintain a value of less than 1 V.

6. The vehicle battery system of claim 1, wherein the three pins comprise: The first pin is configured to switch the cut-off circuit to the on state; The second pin is configured to switch the cutoff circuit to an open state; as well as The third pin is configured as a reference pin for controlling the voltage across the control input and the output of the cutoff circuit.

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