Patent Description:
A vehicle that uses one or more battery systems for providing all or a portion of the motive power for the vehicle can be referred to as an xEV, where the term "xEV" is defined herein to include all of the following vehicles, or any variations or combinations thereof, that use electric power for all or a portion of their vehicular motive force. For example, xEVs include electric vehicles (EVs) that utilize electric power for all motive force. As will be appreciated by those skilled in the art, hybrid electric vehicles (HEVs), also considered xEVs, combine an internal combustion engine propulsion system and a battery-powered electric propulsion system, such as <NUM> Volt (V) or 130V systems. The term HEV may include any variation of a hybrid electric vehicle. For example, full hybrid systems (FHEVs) may provide motive and other electrical power to the vehicle using one or more electric motors, using only an internal combustion engine, or using both. In contrast, mild hybrid systems (MHEVs) disable the internal combustion engine when the vehicle is idling and utilize a battery system to continue powering the air conditioning unit, radio, or other electronics, as well as to restart the engine when propulsion is desired. The mild hybrid system may also apply some level of power assist, during acceleration for example, to supplement the internal combustion engine. Mild hybrids are typically 96V to 130V and recover braking energy through a belt or crank integrated starter generator. Further, a micro-hybrid electric vehicle (mHEV) also uses a "Stop-Start" system similar to the mild hybrids, but the micro-hybrid systems of a mHEV may or may not supply power assist to the internal combustion engine and operate at a voltage below 60V. For the purposes of the present discussion, it should be noted that mHEVs typically do not technically use electric power provided directly to the crankshaft or transmission for any portion of the motive force of the vehicle, but an mHEV may still be considered as an xEV since it does use electric power to supplement a vehicle's power needs when the vehicle is idling with internal combustion engine disabled and recovers braking energy through an integrated starter generator. In addition, a plug-in electric vehicle (PEV) is any vehicle that can be charged from an external source of electricity, such as wall sockets, and the energy stored in the rechargeable battery packs drives or contributes to drive the wheels. PEVs are a subcategory of EVs that include all-electric or battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicle conversions of hybrid electric vehicles and conventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as compared to more traditional gas-powered vehicles using only internal combustion engines and traditional electrical systems, which are typically 12V systems powered by a lead acid battery. For example, xEVs may produce fewer undesirable emission products and may exhibit greater fuel efficiency as compared to traditional internal combustion vehicles and, in some cases, such xEVs may eliminate the use of gasoline entirely, as is the case of certain types of EVs or PEVs.

In addition to use in vehicles (e.g., cars, boats, trucks, motorcycles, airplanes), advances in battery technology and rechargeable batteries are more frequently being used it what may be referred to as stationary battery applications. Applications for stationary batteries, which are often used in backup or supplemental power generation, are becoming more widespread with improvements in rechargeable aspects of batteries and with the lowering of prices for such technology. For example, stationary batteries may be utilized for industrial and/or household applications. Such applications may include DC power plants, substations, back-up power generators, transmission distribution, solar power collection, and grid supply.

<CIT> relates to a conventional battery system for coupling a battery to an electrical system during regenerative braking. The battery system comprises a first battery, a second battery and a battery control unit including a bi-stable relay for connecting/disconnecting the second battery to/from a bus. When the second battery is disconnected from the bus via the bi-stable relay, the battery control unit cannot receive power from the second battery.

<CIT> relates to a conventional apparatus comprising a plurality of battery packs, each comprising a plurality of battery cells, and a battery management system for controlling charge and discharge of the battery packs, wherein power from at least one of the battery packs having a relatively high voltage or state of charge is used to provide operating power for the battery management system. In case a switch is open, the controller of the battery management system is no longer connected to the battery pack and does not receive any power from the battery pack.

<CIT> relates to a further conventional battery system comprising a plurality of battery cells connected in series between a first battery terminal and a second battery terminal, a first relay connected between the first battery terminal and a first output of the battery system, a second relay connected between the second battery terminal and a second output of the battery system, and a controller. The battery system further comprises a third relay connected in series with a resistor of a predefined size between the first battery terminal and the first output and in parallel to the first relay, wherein the control is connected to the relays and configured to open or close the relays by outputting a control signal.

As technology continues to evolve, there is a need to provide power systems with more efficiency for such vehicles, stationary battery applications or systems, and other battery systems. Power systems may be used in a variety of applications to provide power to a load. For example, battery cells may be stored in a container and coupled to the load. The battery cells are charged to provide a power to the load. The less energy used in providing power to the load, the more efficient the power system.

It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers, specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.

The battery systems described herein may be used to provide power to various types of electric vehicles (xEVs) and other high voltage energy storage/expending applications (e.g., electrical grid power storage systems). Such battery systems may include one or more battery modules, each battery module having a number of battery cells (e.g., lithium-ion (Li-ion) electrochemical cells) arranged and electrically interconnected to provide particular voltages and/or currents useful to power, for example, one or more components of an xEV. As another example, battery modules in accordance with present embodiments may be incorporated with or provide power to stationary power systems (e.g., non-automotive systems).

Embodiments of the present disclosure include control systems for strings of battery cells. Battery cells on strings may be selectively coupled to a bus via a relay to provide power to one or more loads on the bus. For example, a mono-stable relay may electrically couple the battery to the bus while the relay receives current. That is, if the mono-stable relay stops receiving current, the relay may open, disconnecting the battery from the bus and electrically isolating the battery from the load.

Because the mono-stable relay receives current while electrically coupled to the bus, the mono-stable relay may use energy to stay in a closed state. Further, many applications may include several battery cells (e.g., <NUM>, <NUM>, <NUM>, <NUM>, or more). For example, a power system may include <NUM> strings that include cell and two relays each. Each of the <NUM> relays may use energy while in a closed state which reduces efficiency of the system. That is, power may be used by the relay to maintain the relay in a closed state. Because there may be several relays (e.g., <NUM>, <NUM>. <NUM>, <NUM>, <NUM>, etc.) in each power system and each relay may use a substantial amount of power, the use of mono-stable relays may reduce the efficiency of the system. For example, in a <NUM> string system, each pair of relays may receive approximately <NUM> Amps of current at <NUM> Volts, resulting in the use of <NUM> Watts to control the operation of the relays. As such, mono-stable relays may use significant energy to provide power to the load and overall efficiency of the system may be reduced. Note that the values used above are simply meant to be illustrative and any suitable numbers of relays may receive any suitable amount of current to operate in various power systems.

Hi-stable relays may reduce the energy lost in controlling the relay by maintaining a state of the bi-stable relay without receiving additional current. That is, a bi-stable relay receives current for a period of time and remains open or closed after the period of time. As such, the bi-stable relay may electrically couple the battery to the one or more loads after the current has stopped flowing due to the bi-stable relay maintaining the state (e.g., open or closed) of the bi-stable relay. For example, a bi-stable relay may connect the battery cell to the bus upon receiving current for <NUM> milliseconds to enable the battery to provide power to the one or more loads. Then, the bi-stable relay may not continue to receive additional current and maintain a closed state in which the battery provides power to the one or more loads. The bi-stable relay may then receive current for another <NUM> milliseconds to open the bi-stable relay and electrically decouple the battery from the bus.

To control the state of the bi-stable relay, the bi-stable relay may be operatively coupled to a control system. The control system may include a controller that maintains the state of the bi-stable relay and sends signal(s) to control operation of the bi-stable relay based on the current state and a desired state. For example, in the event of a fault, the controller may send a control signal to the bi-stable relay to cause the bi-stable relay to open to disconnect the battery cells from the bus. That is, the controller may determine whether the bi-stable relay is currently in a closed state. If the controller is in the closed state, the controller may send a control signal (e.g., pulse) instructing the bi-stable relay to open and disconnect the battery cells.

Further, in the event of the fault, the control system may switch the bi-stable relay via power from the battery cell. During operation, the control system and/or the bi-stable relay may be powered from a primary power source to maintain balance within each of the battery cells. The primary power source may be referred to as a low voltage power source having a voltage lower than the battery cell voltage. In the event of a fault (e.g., short circuit) or other event in which the primary source is unavailable, the control system may control operation of the bi-stable relay using power from the battery cells. For example, the control system may send a signal, via power from the battery cells, indicative of instructions to open the bi-stable relay to disconnect the battery cells from the bus while the primary source is unavailable.

To help illustrate, <FIG> is a perspective view of an embodiment of a vehicle <NUM>, which may utilize a regenerative braking system and features in accordance with present embodiments. Although the following discussion is presented in relation to vehicles with regenerative braking systems, the techniques described herein are adaptable to other vehicles that capture/store electrical energy with a battery, which may include electric-powered and gas-powered vehicles. Further, the techniques described herein may also be adaptable to other high voltage energy storage/expending applications. such as stationary battery systems (e.g., electrical grid power storage systems).

As discussed above, it may be desirable for a battery system <NUM> to be largely compatible with traditional vehicle designs. Accordingly, the battery system <NUM> may be placed in a location in the vehicle <NUM> that would have housed a traditional battery system. For example, as illustrated, the vehicle <NUM> may include the battery system <NUM> positioned similarly to a lead-acid battery of a typical combustion-engine vehicle (e.g., under the hood of the vehicle <NUM>). Furthermore, as will be described in more detail below, the battery system <NUM> may be positioned to facilitate managing temperature of the battery system <NUM>. For example, in some embodiments, positioning a battery system <NUM> under the hood of the vehicle <NUM> may enable an air duct to channel airflow over the battery system <NUM> and cool the battery system <NUM>.

In other words, the battery system <NUM> may supply power to components of the vehicle's electrical system, which may include radiator cooling fans, climate control systems, electric power steering systems, active suspension systems, auto park systems, electric oil pumps, electric super/turbochargers, electric water pumps, heated windscreen/defrosters, window lift motors, vanity lights, tire pressure monitoring systems, sunroof motor controls, power seats, alarm systems, infotainment systems, navigation features, lane departure warning systems, electric parking brakes, external lights, or any combination thereof. Illustratively, in the depicted embodiment, the energy storage component <NUM> supplies power to the vehicle console <NUM>, a display <NUM> within the vehicle, and the ignition system <NUM>, which may be used to start (e.g., crank) an internal combustion engine <NUM>.

Additionally, the energy storage component <NUM> may capture electrical energy generated by the alternator <NUM> and/or the electric motor <NUM>. In some embodiments, the alternator <NUM> may generate electrical energy while the internal combustion engine <NUM> is running. More specifically, the alternator <NUM> may convert the mechanical energy produced by the rotation of the internal combustion engine <NUM> into electrical energy. Additionally or alternatively, when the vehicle <NUM> includes an electric motor <NUM>, the electric motor <NUM> may generate electrical energy by converting mechanical energy produced by the movement of the vehicle <NUM> (e.g., rotation of the wheels) into electrical energy. Thus, in some embodiments, the energy storage component <NUM> may capture electrical energy generated by the alternator <NUM> and/or the electric motor <NUM> during regenerative braking. As such, the alternator <NUM> and/or the electric motor <NUM> are generally referred to herein as a regenerative braking system.

To facilitate capturing and supplying electric energy, the energy storage component <NUM> may be electrically coupled to the vehicle's electric system via a bus <NUM>. For example, the bus <NUM> may enable the energy storage component <NUM> to receive electrical energy generated by the alternator <NUM> and/or the electric motor <NUM>. Additionally, the bus <NUM> may enable the energy storage component <NUM> to output electrical energy to the ignition system <NUM> and/or the vehicle console <NUM>. Accordingly, when a <NUM> volt battery system <NUM> is used, the bus <NUM> may carry electrical power typically between <NUM> and <NUM> volts.

Additionally, as depicted, the energy storage component <NUM> may include multiple battery modules. For example, in the depicted embodiment, the energy storage component <NUM> includes a lead acid (e.g., a first) battery module <NUM> in accordance with present embodiments, and a lithium ion (e.g., a second) battery module <NUM>, where each battery module <NUM> includes one or more battery cells. In other embodiments, the energy storage component <NUM> may include any number of battery modules. Additionally, although the first battery module <NUM> and the second battery module <NUM> are depicted adjacent to one another, they may be positioned in different areas around the vehicle. For example, the second battery module <NUM> may be positioned in or about the interior of the vehicle <NUM> while the first battery module <NUM> may be positioned under the hood of the vehicle <NUM>.

In some embodiments, the energy storage component <NUM> may include multiple battery modules to utilize multiple different battery chemistries. For example, the first battery module <NUM> may utilize a lead-acid battery chemistry and the second battery module <NUM> may utilize a lithium ion battery chemistry. In such an embodiment, the performance of the battery system <NUM> may be improved since the lithium ion battery chemistry generally has a higher coulombic efficiency and/or a higher power charge acceptance rate (e.g., higher maximum charge current or charge voltage) than the lead-acid battery chemistry. As such, the capture, storage, and/or distribution efficiency of the battery system <NUM> may be improved.

To facilitate controlling the capturing and storing of electrical energy, the battery system <NUM> may additionally include a control module <NUM>. More specifically, the control module <NUM> may control operations of components in the battery system <NUM>, such as relays (e.g., switches) within energy storage component <NUM>, the alternator <NUM>, and/or the electric motor <NUM>. For example, the control module <NUM> may regulate an amount of electrical energy captured/supplied by each battery module <NUM> or <NUM> (e.g., to de-rate and re-rate the battery system <NUM>), perform load balancing between the battery modules <NUM> and <NUM>, determine a state of charge of each battery module <NUM> or <NUM>, determine temperature of each battery module <NUM> or <NUM>, determine a predicted temperature trajectory of either battery module <NUM> or <NUM>, determine predicted life span of either battery module <NUM> or <NUM>, determine fuel economy contribution by either battery module <NUM> or <NUM>, control magnitude of voltage or current output by the alternator <NUM> and/or the electric motor <NUM>, and the like.

Accordingly, the control module <NUM> may include one or more processors <NUM> and one or more memories <NUM>. More specifically, the one or more processors <NUM> may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof. Generally, the processor <NUM> may perform computer-readable instructions related to the processes described herein. Additionally, the processor <NUM> may be a fixed-point processor or a floating-point processor.

The one or more memories <NUM> may include volatile memory, such as random access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, or solid-state drives. In some embodiments, the control module <NUM> may include portions of a vehicle control unit (VCU) and/or a separate battery control module. Additionally, as depicted, the control module <NUM> may be included separate from the energy storage component <NUM>, such as a standalone module. In other embodiments, the battery management system <NUM> may be included within the energy storage component <NUM>.

In certain embodiments, the control module <NUM> or the processor <NUM> may receive data from various sensors <NUM> disposed within and/or around the energy storage component <NUM>. The sensors <NUM> may include a variety of sensors for measuring current, voltage, temperature, and the like regarding the battery module <NUM> or <NUM>. After receiving data from the sensors <NUM>, the processor <NUM> may convert raw data into estimations of parameters of the battery modules <NUM> and <NUM>. As such, the processor <NUM> may render the raw data into data that may provide an operator of the vehicle <NUM> with valuable information pertaining to operations of the battery system <NUM>, and the information pertaining to the operations of the battery system <NUM> may be displayed on the display <NUM>. The display <NUM> may display various images generated by device <NUM>, such as a graphical user interface (GUI) for an operating system or image data (including still images and video data). The display <NUM> may be any suitable type of display, such as a liquid crystal display (LCD), plasma display, or an organic light emitting diode (OLED) display, for example. Additionally, the display <NUM> may include a touch-sensitive element that may provide inputs to adjust parameters of the control module <NUM> or data processed by the processor <NUM>.

The energy storage component <NUM> may have dimensions comparable to those of a typical lead-acid battery to limit modifications to the vehicle <NUM> design to accommodate the battery system <NUM>. For example, the energy storage component <NUM> may be of similar dimensions to an H6 battery, which may be approximately <NUM> inches x <NUM> inches x <NUM> inches. As depicted, the energy storage component <NUM> may be included within a single continuous housing. In other embodiments, the energy storage component <NUM> may include multiple housings coupled together (e.g., a first housing including the first battery <NUM> and a second housing including the second battery <NUM>). In still other embodiments, as mentioned above, the energy storage component <NUM> may include the first battery module <NUM> located under the hood of the vehicle <NUM>, and the second battery module <NUM> may be located within the interior of the vehicle <NUM>.

The energy storage component <NUM> may be located on a string having a relay. The control module <NUM> may send a signal to control operation of the relay. In some embodiments, the control module may include a controller that monitors a state of the relay and controls the relay based on the state. As explained below, the controller may send a signal indicative of instructions to open the relay in an event where a primary source is not providing power (e.g. due to a fault, a short, a disconnect, etc.). Further, the controller may temporarily use power from battery cells of the battery modules <NUM> and <NUM> to provide the signal.

<FIG> is an embodiment of a power system, such as the battery system <NUM> of the vehicle <NUM>, a stationary power system, or the like. The power system includes the energy storage component <NUM> on the DC bus <NUM> that provides power to one or more loads <NUM>. The DC bus <NUM> may include one or more strings <NUM> that each have one or more battery cells <NUM>. Strings <NUM> may be referred to as a set of battery cells electrically connected to provide power to a bus. While one string <NUM> and one battery cell <NUM> is shown in <FIG>, this is meant to be illustrative, and any suitable number of strings and battery cells (e.g., battery modules <NUM> and <NUM> of <FIG>) may be used. Additional strings may be added in parallel as indicated by phantom lines <NUM> to electrically couple the battery cells between the sides of the bus <NUM>. Between the battery cells <NUM> of the energy storage component <NUM> and the DC bus <NUM>, the string <NUM> may include one or more relays, such as a bi-stable relay <NUM>. The bi-stable relay <NUM> may be an electrically controlled switch that selectively and electrically couples the battery cell <NUM> to the DC bus <NUM> depending on a state of the bi-stable relay <NUM>. That is, the bi-stable relay <NUM> may be in an open state, in which the battery cell <NUM> is electrically disconnected from the DC bus <NUM>, or in a closed state, in which the battery cell <NUM> is electrically connected to the DC bus <NUM> to provide power to the one or more loads <NUM>.

Mono-stable relays may electrically connect the battery cell <NUM> to the DC bus <NUM> while the relay receives current. That is, the mono-stable relay may be closed for a period that depends on a duration that the mono-stable relay receives current. Because the mono-stable relay receives current throughout the duration in which the mono-stable relay is closed, the power used to maintain the mono-stable relay in the closed state may reduce the overall efficiency of the power system. As explained above, if the power system includes several strings <NUM>. maintaining the mono-stable relay in the closed state by consistently providing current to the relay consumes a significant amount of power.

The bi-stable relay <NUM> may improve efficiency of the power system by switching states via a pulse of a voltage, a current, or both. Upon receiving the pulse. the state of the bi-stable relay <NUM> may be switched from an open state to a closed state or from a closed state to an open state and remain in the state after the pulse. For example, the bi-stable relay <NUM> may receive current for a duration (e.g., <NUM> millisecond, <NUM> milliseconds, <NUM> milliseconds, <NUM> milliseconds, etc.), stop receiving current after the duration, change states (e.g., from an open state to a closed state or from a closed state to an open state), and remain in the changed state after receiving the current. As such, the bi-stable relay <NUM> may electrically couple the battery cell <NUM> to the DC bus <NUM> upon receiving a pulse of a voltage, a current, or both, and continue electrically coupling the battery cell <NUM> to the DC bus <NUM> after the pulse, thereby reducing the amount of power consumed while the battery cell <NUM> and the DC bus <NUM> are electrically coupled.

The control module <NUM> may be used to control operation of the bi-stable relay <NUM>. The control module <NUM> may include a controller <NUM> operatively coupled (e.g., electrically coupled using an electrical conductor that conducts current) to the bi-stable relay <NUM> (e.g., a gate of the bi-stable relay) to send electrical signal(s) (e.g., voltage or current pulses) to control operation of the bi-stable relay <NUM>. That is, the controller <NUM> may include circuitry or hardware configured to maintain (e.g., store via memory or monitor via a sensor) the state of the bi-stable relay <NUM> and to send signal(s) to the bi-stable relay <NUM> indicative of instructions (e.g., pulses) to switch the state of the bi-stable relay <NUM> based on the maintained (e.g., current) state of the bi-stable relay. The controller <NUM> may be a microcontroller, field-programmable gate array (FPGA), application specific integrated circuit (ASIC), or some combination thereof. The controller may include a processor <NUM>, or multiple processors, such as one or more "general-purpose" microprocessors, one or more special-purpose microprocessors, or some combination thereof. For example, the processor <NUM> may include one or more reduced instruction set (RISC) processors, advanced RISC machine (ARM) processors, performance optimization with enhanced RISC (PowerPC) processors, or any other suitable processing device.

The controller <NUM> may also include one or more storage devices and/or other suitable components, such as a memory <NUM>, operatively coupled to the processor <NUM> to execute software, such as software for controlling the bi-stable relay <NUM>, and so forth. The memory <NUM> may include a volatile memory, such as random access memory (RAM), nonvolatile memory, such as read-only memory (ROM), flash memory, or any combination thereof. The memory <NUM> may store a variety of information that may be used for various purposes. For example, the memory <NUM> may store processor-executable instructions (e.g., firmware or software) for the processor <NUM> to execute, such as instructions for controlling the bi-stable relay <NUM>. The storage devices) (e.g., nonvolatile storage) may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The storage device(s) may store data (e.g., the state of the relay), instructions (e.g., software or firmware for controlling the bi-stable relay <NUM>), and any other suitable data.

The controller <NUM> may receive power from a primary source <NUM>, such as the electric motor <NUM>, the internal combustion (IC) engine <NUM>, a power grid, or the like. The primary source <NUM>, also referred to as a low voltage (LV) power source, may provide power at a lower voltage than the higher voltage of the battery cell <NUM>. For example, the primary source <NUM> may provide <NUM> Volt power to the controller <NUM> to enable the controller <NUM> to control the bi-stable relay <NUM> during operation. Further, the power system may include isolation circuitry <NUM> that isolates the LV components (e.g., hardware, circuitry, etc.) of the power system from the high voltage (HV) components (e.g., hardware, circuitry, etc.), such as the battery cell <NUM> and the DC bus <NUM>.

During operation, the controller <NUM> may control operation of the bi-stable relay <NUM> via the power received from the primary source <NUM>. The controller <NUM> may control the state of the bi-stable relay <NUM>. For example, the controller <NUM> may store in the memory <NUM> an indication (e.g., open or closed) of the current state of the bi-stable relay <NUM>. In other embodiments, the controller <NUM> may detect, via a sensor <NUM> (e.g., voltage sensor, current sensor, etc.), a sensor signal indicative of the current state of the bi-stable relay <NUM>. The controller <NUM> may then send a control signal indicative of instructions to control the state of the bi-stable relay <NUM> based on the current state and/or a desired state. For instance, if the bi-stable relay <NUM> is currently in a closed state, the controller <NUM> may send a pulse to open the bi-stable relay <NUM> and update the state in the memory <NUM> to indicate that the bi-stable relay <NUM> is open.

Using the battery cells <NUM> to power the controller <NUM> regardless of the primary source <NUM> may increase imbalance in the battery cells <NUM> (e.g., due to drawing more power from certain cells more than other cells to power the controller <NUM>). Further, if a fault occurs (e.g., on the high voltage side, the low voltage, or both), it may be desirable to control the bi-stable relay <NUM> while the primary source <NUM> is unavailable. As such, in an event where the primary source <NUM> does not provide power to the controller <NUM>, the controller <NUM> may control the bi-stable relay <NUM>, via power from the battery cell <NUM>, to electrically disconnect the battery cell <NUM> from the DC bus <NUM>. That is, the controller <NUM> may control the bi-stable relay <NUM> via power from the battery cell <NUM> during the event where the primary source <NUM> does not provide power (e.g., during a fault, short circuit, or outage), and otherwise control the bi-stable relay <NUM> via power from the primary source <NUM> to reduce imbalance caused by drawing power from the battery cell <NUM>. That is, in certain embodiments, the controller may minimize an amount of power drawn from battery cells <NUM> to control the bi-stable relay <NUM> and to otherwise control the bi-stable <NUM> using the primary source <NUM>. In some embodiments, the controller <NUM> may detect whether the primary source <NUM> is providing power. The controller <NUM> may draw power from the battery cell <NUM> to open the bi-stable relay <NUM> and to shut down operation of the battery cell <NUM>.

<FIG> is a schematic diagram of the battery system <NUM> of <FIG> for a string <NUM>. In the illustrated embodiment, the control module <NUM> includes controllers <NUM> and <NUM>. The controllers <NUM> and <NUM> may include hardware and/or circuitry similar to those described with respect to the controller <NUM> of <FIG>. While two controllers are used, this is meant to be illustrative, and one, two, three, four, or any other suitable number of controllers may be used. The controllers <NUM> and <NUM> may each include one or more input/output ports that are programmed to send signal(s) indicative of instructions to control operation of the bi-stable relays <NUM> and <NUM>, respectively. As described above, the controllers <NUM> and <NUM> may store the state of the bi-stable relays <NUM> and <NUM> in memory, detect the state of the bi-stable relays <NUM> and <NUM> (e.g., via signals from voltage or current sensors on the DC bus <NUM>, the string <NUM>, the bi-stable relay, etc.), or any combination thereof. The controllers <NUM> and <NUM> may send control signal(s) to the respective bi-stable relays <NUM> and <NUM> to close the relays <NUM> and <NUM> to enable the battery cell <NUM> to provide power to the bus <NUM>. The battery system <NUM> includes a first bi-stable relay <NUM> between the battery cell <NUM> and a first side of the bus <NUM> and a second bi-stable relay <NUM> between the battery cell <NUM> and a second side of the bus <NUM>, opposite the first side, to improve the robustness of the battery system <NUM>.

In the illustrated embodiment, each of the controllers <NUM> and <NUM> control an operation in addition to the respective bi-stable relays <NUM> and <NUM>. The controller <NUM> is operatively coupled to the bi-stable relay <NUM> as well as a pre-charge circuit <NUM> having a resistor to limit the current due to capacitance on the DC bus <NUM>. That is, the controller <NUM> may send signal(s) to control the pre-charge circuit <NUM> to reduce an impact on the bi-stable relay <NUM> from capacitance on the bus <NUM>. As another example, controller <NUM> is operatively coupled to a relay <NUM>. The controller <NUM> may send a signal to the relay to open or close the relay to electrically couple an alternating current (AC) source (e.g., a source other than the battery cells <NUM>) to an auxiliary load, such as a fan <NUM>. The string <NUM> may also include a service disconnect <NUM> to manually disconnect the battery cells <NUM> to perform services on the string <NUM>.

<FIG> is a block diagram of the battery system <NUM> of <FIG> for a string <NUM> with multiple battery cells <NUM>. Each of the battery cells <NUM> may be electrically coupled to corresponding monitoring circuitry <NUM>. Each string <NUM> may include any suitable number of cells and corresponding monitoring circuitry. Each of the monitoring circuitry <NUM> may send signals to a controller <NUM> indicative of health of the corresponding battery cell. Further, the controller <NUM> may send signal(s) to control a bi-stable relay <NUM> based on the health of the battery cells <NUM>, the health of the bus <NUM>, or the like. As mentioned above, the controller <NUM> may be coupled to one or more other loads, such as a pre-charge circuit, a relay for an AC fan, or the like.

Claim 1:
A control system for one or more battery cells (<NUM>, <NUM>, <NUM>), comprising:
- a bi-stable relay (<NUM>, <NUM>, <NUM>) configured to electrically connect the one or more battery cells (<NUM>, <NUM>, <NUM>) to a bus (<NUM>, <NUM>, <NUM>) when a state of the bi-stable relay (<NUM>, <NUM>, <NUM>) is in a first state, electrically disconnect the one or more battery cells (<NUM>, <NUM>, <NUM>) from the bus (<NUM>, <NUM>, <NUM>) when the state of the bi-stable relay (<NUM>, <NUM>, <NUM>) is in a second state, and to remain in the first or second state until instructed to switch the state by a control signal; and
- a controller (<NUM>, <NUM>, <NUM>, <NUM>) coupled to the one or more battery cells (<NUM>, <NUM>, <NUM>),
characterized in that
the controller (<NUM>, <NUM>, <NUM>, <NUM>) is configured to:
- be operatively coupled to the bi-stable relay (<NUM>, <NUM>, <NUM>) and send the control signal;
- receive power from a primary source (<NUM>);
- control operation of the bi-stable relay (<NUM>, <NUM>, <NUM>) using power from the primary source (<NUM>); and
- receive power from the one or more battery cells (<NUM>, <NUM>, <NUM>) to control operation of the bi-stable relay (<NUM>, <NUM>, <NUM>) using the power from the one or more battery cells (<NUM>, <NUM>, <NUM>) in an event where the primary source (<NUM>) does not provide power, while the bi-stable relay (<NUM>, <NUM>, <NUM>) is in the second state, wherein the one or more battery cells (<NUM>, <NUM>, <NUM>) is disconnected from the bus (<NUM>, <NUM>, <NUM>).