Description:FIELD OF THE INVENTION
[0001] The present subject matter is related, in general to a battery pack, and more particularly, but not exclusively to a system and method for derating current in the battery pack.
BACKGROUND OF THE INVENTION
[0002] In the development of battery technology for industrial applications there exist critical safety concerns with regard to propensity of fire hazards as well as concerns regarding the battery cycle life. In view of the popularity battery packs hold in our day-to-day life there is a dire need for development of appropriate infrastructure which monitor the real time functioning of the battery packs as well as adapt the configuration of the battery pack to suit energy requirements. Additionally, in order to suit high power applications in the automotive and concomitant industries there is a requirement of higher durability and longer life cycle of the battery pack.
[0003] Battery packs, in essence, are a source of electrical energy which is supplied to an electrical load for its functioning. The battery pack consists of a plurality of battery cells which are electrically connected in parallel, or series configuration based on the required power output and current output to be supplied by the battery pack. Battery packs are used in a broad spectrum of industrial applications and equipment and are also a critical component in electric and hybrid vehicle development.
[0004] While it is known in the art, to provide the battery pack with a Battery Management System (hereinafter referred to as BMS) which monitors individual parameters of the cells comprising the battery pack. The parameters monitored by the BMS include State of Charge and a State of Health of the battery pack. However, the BMS, in plenary terms, plays a passive role in monitoring and processing the battery pack parameters but fails to adopt or execute any active mechanism which addresses concerns of battery durability, battery life and even any form of fault correction.
[0005] Additionally, battery pack are configured to have a peak rating and a continuous rating at which power, voltage and currents are delivered to an external load. Derating is a method by which the power, voltage and current supplied by the battery pack are manipulated to ensure longer durability and cycle life of the battery pack. Derating techniques implemented in battery packs are based on a calendar life or life cycle provided by the manufacturer and fail to encompass actual operating parameters of the battery pack, leading to imprecise derating of the power, voltage and currents in the battery pack.
[0006] Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of described systems with some aspects of the present disclosure, as set forth in the remainder of the present application and with reference to the drawings.
SUMMARY
[0007] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
[0008] According to embodiments illustrated herein, the present subject matter relates to a system for derating currents in a battery pack. The system comprises a plurality of cells, an external load and a control unit. The external load is electrically connected to the plurality of cells. The control unit is communicatively connected to the plurality of cells and the external load. The control unit is configured to: receive a plurality of cell parameters from the plurality of cells; determine a dynamic threshold of the plurality of cells, wherein the dynamic threshold being associated with the plurality of cell parameters; regulate supply of current from the plurality of cells to the external load on satisfaction of a first set of pre-defined conditions, wherein the supply of current being regulated by a pre-defined factor.
[0009] According to embodiments illustrated herein, the present subject matter additionally provides a method for derating current in a battery pack, the method comprising steps: receiving, by a control unit, a pre-set plurality of cell parameters from a plurality of cells disposed in the battery pack; configuring, by the control unit, the plurality of cells to supply a pre-defined current limit to an external load over a first pre-defined period of time, wherein the external load being electrically connected to the plurality of cells, and wherein the pre-defined current limit being associated with the pre-set plurality of cell parameters; receiving, by the control unit, a plurality of cell parameters from the plurality of cells; determining, by the control unit, a dynamic threshold of the plurality of cells; and configuring, by the control unit, to regulate a supply of current of the plurality of cells to the external load on satisfaction of a first set of pre-defined conditions, wherein the supply of current to the external load being regulated by a pre-defined factor. In an aspect of the present invention, the dynamic threshold of the plurality of cells is associated with the plurality of cell parameters.
[00010] According to embodiments illustrated herein, the dynamic threshold of the plurality of cells being at least one of a current threshold, a power threshold and an energy threshold determined based on an energy count of the plurality of cells, wherein the energy count being determined based on the plurality of cell parameters.
BRIEF DESCRIPTION OF THE DRAWINGS
[00011] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention.
[00012] Figure 1 exemplarily illustrates a block diagram of a system environment, in accordance with some embodiments of the present disclosure.
[00013] Figure 2 illustrates a block diagram depicting one or more components of the system environment, in accordance with some embodiments of the present disclosure.
[00014] Figure 3 depicts a flowchart illustrating a method for derating current in a battery pack, in accordance with some embodiments of the present disclosure.
[00015] Figure 4 depicts flowchart for implementation of an exemplary embodiment of a control unit, in accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION
[00016] The present disclosure may be best understood with reference to the detailed figures and description set forth herein. Various embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed descriptions given herein with respect to the figures are simply for explanatory purposes as the methods and systems may extend beyond the described embodiments. For example, the teachings presented and the needs of a particular application may yield multiple alternative and suitable approaches to implement the functionality of any detail described herein. Therefore, any approach may extend beyond the particular implementation choices in the following embodiments described and shown.
[00017] References to “one embodiment,” “at least one embodiment,” “an embodiment,” “one example,” “an example,” “for example,” and so on indicate that the embodiment(s) or example(s) may include a particular feature, structure, characteristic, property, element, or limitation but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Further, repeated use of the phrase “in an embodiment” does not necessarily refer to the same embodiment.
[00018] The present invention now will be described more fully hereinafter with different embodiments. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather those embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art.
[0001] The present invention is illustrated with a battery pack. However, a person skilled in the art would appreciate that the present invention is not limited to a battery pack and certain features, aspects and advantages of embodiments of the present invention can be extended to other forms of energy storage devices used with various types of vehicles, electric vehicle, hybrid vehicles and other forms of electrical and electronic equipment requiring an energy storage device. In an embodiment, the battery pack is configured to supply electrical energy to an external electrical load. The electrical load refers to, but is not limited to, electrical vehicles, hybrid vehicles and other electrical and electronic equipment requiring electrical energy. Additionally, the term “vehicle” used in the present disclosure shall not be narrowly construed to relate to two, three or four-wheeler vehicles but shall be extended to multi-axle vehicles and encompasses all forms of mobility and locomotion capable of drawing or utilizing electrical energy from a battery pack or an energy storage device for its operation.
[00019] The object of the present subject matter is to provide a system and method for derating currents in the battery pack based on a plurality of cell parameters received in real-time by a control unit.
[00020] Conventional battery packs in operation have a designated peak current value, a designated peak voltage value and a designated peak power rating, where the peak values represent the maximum permissible limits of the cell parameters the battery pack is capable of delivering. The peak values of power, current and voltage are typically required for starting an electrical appliance or a vehicle represented by the external load. Additionally, the manufacturer provides a designated continuous current value, a designated continuous voltage value and a designated continuous power rating. The continuous values of power, current and voltage represent the power, current and voltage the battery pack is capable of supplying in a continuously fashion after establishing the electrical connection or starting the external load which is drawing the current from the battery pack.
[00021] While, delivery of peak current, peak voltage and peak power is essential for starting the external load but provision of the same over a pro-longed period of time would lead to overheating of the battery pack as well as reduced life cycle and durability of the battery pack. During initializing of the battery pack, the battery pack has a pre-set energy capacity, the energy of the battery pack being drawn by the external load at peak values would lead to faster degradation of the battery pack.
[00022] Consequently, the external load may also draw current from the battery pack between the peak current value and the continuous current value, which would again lead to overheating and eventual battery degradation and affected durability and life cycle of the battery pack.
[00023] The present invention addresses this exact technical problem persistent in conventional battery packs by providing a system and method for derating the current in the battery pack based on a determined dynamic threshold by a control unit. The dynamic threshold is based on received plurality of cell parameters from the plurality of cells of the battery pack and comprises of a current threshold, a power threshold and an energy threshold based on an energy count of the plurality of cells. Additionally, the dynamic threshold of the battery pack is re-evaluated after a pre-set period of time to ensure that the regulation of the current supplied to the external load is optimized effectively. The configuration as per the present disclosure ensures that the current supplied to the external load is optimized based on requirement of the external load as well as the ability of the plurality of cells to satisfy the requirement of the external load. The disclosed configuration enhances the durability and life cycle of the battery pack and addresses heating concerns of the battery pack. Further, the control unit effectively monitors the plurality of cell parameters to ensure safe operation of the battery pack.
[00024] The disclosed configuration ensures that the pre-set plurality of cell parameters comprising of peak values are only supplied over a first pre-defined period of time followed by optimization of the current being supplied based on dynamic threshold determination.
[00025] In conventional mechanisms relating to derating of current in battery packs, the operating conditions are based on calendar and cycle ageing of the battery pack while neglecting aspects of internal resistance of the battery pack. Parameters such as calendar and cycle ageing of battery pack despite being crucial in estimation of derating values are deemed static and tested in initial phases of battery pack manufacturing. Factors such as working environment affecting the degradation in capacity affect the durability of the battery pack which requires a re-calibration of cycle ageing and calendar life. Thus, the conventional mechanisms fail to provide a precise estimation on the derating of currents in the battery pack.
[00026] The present subject matter addresses the drawbacks of conventional mechanisms pertaining to derating in battery packs by considering dynamic aspects based on energy count of the plurality of cells in determination of dynamic threshold over short term data received from the plurality of cells. The short term data is defined over a pre-set period of time between which the control unit receives a plurality of cell parameters. The internal resistance aspects of the battery pack are already included in the pre-defined derating value.
[00027] The object of the present subject matter is to provide a battery pack configured to determine a safe operating zone to effectively secure the operating environment as well as the battery pack itself from instances of thermal runaway, short circuit and overheating.
[00028] To this end, the plurality of cells of the battery pack are communicatively connected to the control unit, wherein the control unit based on the received plurality of cell parameters from the plurality of cells, determines a dynamic threshold. The dynamic threshold determined represents safe operating limits of the plurality of cells with reference to the external load, in terms of current threshold, power threshold and energy thresholds. Further, the control unit being configured to re-evaluate dynamic threshold of the plurality of cells after a pre-set period of time ensures the maintenance of safe operating limits of the plurality of cells and proffers a secure operating environment. Further, the plurality of cell parameters comprises at least one of a state of charge, a state of health, a current, a power, a voltage and a temperature of the plurality of cells in determination of the dynamic threshold, thus addressing concerns of thermal runaway, overheating and short circuits in the plurality of cells.
[00029] In an aspect, the control unit when posed with detected cell imbalances configures a cell balancing circuit to balance the cell voltages in the plurality of cells and also configures a regulating circuit to derate the current from the plurality of cells based on the determined dynamic threshold.
[00030] The present subject matter not only monitors the plurality of cell parameters but also employs an active mechanism comprising of a control unit, a cell balancing circuit and a regulating circuit to sermonize concerns of cell imbalances, thermal runaway, short circuit, overheating and even safe operating limits of operation of the battery pack.
[00031] In conventional battery packs, the battery pack is provided with a battery management system configured to passively diagnose cell imbalances in the battery pack and other miscellaneous anomalies in the battery pack. The limitations associated with conventional battery packs is the absence of an active coping mechanism to address the concerns of cell imbalances, short circuit and overheating, which the present subject matter effectively addresses. In an embodiment, the control unit in accordance with the present disclosure is integrated with the battery management system in conventional battery packs.
[00032] The object of the present subject matter is to provide a system and method for derating currents in the battery pack in achieving a comfortable user experience when the battery pack be used in high power applications like those of powertrain in vehicles.
[00033] In an embodiment, the external load is a motor of a powertrain of a vehicle, wherein the term vehicle refers to a hybrid as well as an electric vehicle. The control unit as per the present disclosure is configured to regulate the supply of current from the plurality of cells to the external load by a pre-defined factor wherein the pre-defined factor is associated with a pre-defined derating value and a temperature of the plurality of cells. The regulation of current by a pre-defined factor ensures that the current, power and energy being supplied to the external load transitions in a gradual yet swift manner leading to a better and more convenient driving experience despite reduction in power achieved at the wheels. Further, based on energy count of the plurality of cells the dynamic threshold is modified after a pre-set period of time, this permits the control unit to re-configure the plurality of cells to supply current at a higher rating when the same is available in the plurality of cells. In this scenario, again the current is regulated by the pre-defined factor to the new dynamic threshold limits to provide higher power at the wheels, a smooth driving experience and improved performance of the vehicle.
[00034] Further, conforming with automotive standards the control unit, as per the present disclosure, is configured to quickly determine the dynamic threshold of the plurality of cells to achieve a quicker, swifter and smoother regulation of current being supplied to the powertrain of the vehicle. Additionally, the determination of the dynamic threshold after a pre-set period of time ensures continuity and minimal gap between the transmission of regulation inputs from the control unit to the powertrain of the vehicle. The faster determination of dynamic threshold serves an essential pre-requisite in high power applications such as in the powertrains of vehicles.
[00035] The embodiments of the present invention will now be described in detail with reference to a battery pack along with the accompanying drawings. However, the present invention is not limited to the present embodiments. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00036] Figure 1 exemplarily illustrates a block diagram of a system environment, in accordance with some embodiments of the present disclosure.
[00037] With reference to Figure 1, 100 denotes a system environment for derating currents in a battery pack, 102 denotes a battery pack, 104 denotes an external load, 106 denotes a plurality of cells, 108 denotes a control unit, 110 denotes a controller, 112 denotes a DC-DC converter and 114 denotes an intermediate control unit.
[00038] In an aspect, the battery pack (102) comprises of a plurality of cells (106) and a control unit (108). The plurality of cells (106) is communicatively as well as electrically connected to the control unit (108).
[00039] In an aspect, the current, power and voltage exiting the battery pack (102) is supplied to an external load (104). In another aspect, the current, power and voltage exiting the battery pack (102) is supplied to a DC-DC converter (112), wherein the DC-DC converter (112) supplies the current, power and voltage after conversion to an intermediate control unit (114)
[00040] In an aspect, the control unit (108), the controller (110) of the external load (104) and the intermediate control unit (114) are communicatively connected to each other. The control unit (108) is communicatively connected to the external load (104) through the controller (110).
[00041] In an aspect, the plurality of cells (106) of the battery pack (102) is electrically connected to the external load (104) and is configured to supply current, power and voltage to the external load (104).
[00042] In an aspect, the battery pack (102) encompasses other forms of energy storage devices such as the battery packs used in electric vehicle, hybrid vehicles and even internal combustion vehicles and the like and is hereinafter neither limited by application nor by semantics.
[00043] In an aspect, the battery pack (102) comprises of a plurality of cells (106) where the plurality of cells (106) is electrically connected to each other. In an embodiment, the battery pack (102) comprises a battery management system (hereinafter referred to as BMS) (not shown), wherein the plurality of cells (106) are electrically connected to the BMS.
[00044] The term battery pack (102) used in the present disclosure shall be construed to include any electrical equipment configured to store electrical energy and may include a plurality of cells, a plurality of battery modules or other forms of electrical energy storage equipment. The battery pack (102) is an energy storage device or an energy storage pack which is configured to store electrical energy and supply the stored electrical energy to an external electrical load as and when required.
[00045] In an aspect, the battery pack (102) may be rechargeable or non-rechargeable dependent on the application for which the battery pack (102 is used. The battery pack (100) has a charged and a discharged state.
[00046] In an embodiment, the battery pack (102) consists of a plurality of battery modules connected in series, with each battery module having a plurality of cells (106) connected in parallel. In an aspect, the plurality of cells (106) are disposed in one or more holders which hold the cells in the required position to maintain cell arrangement and cell spacing. The battery pack (102) includes one or more interconnectors which establish an electrical connection between the plurality of cells (106) disposed in a battery module. In another aspect, the plurality of cells (106) may be stacked in a battery module wherein the plurality of cells (106) inside the battery module being connected in parallel. A plurality of battery modules may then be connected in series to form the plurality of cells (106) as illustrated and in accordance with the present disclosure.
[00047] In another embodiment, the battery pack (102) comprises of the plurality of cells (106) where the plurality of cells (106) are electrically connected in at least one of series, parallel or a combination of series and parallel connections.
[00048] In an aspect, the battery pack (102) comprises of a control unit (108). The control unit (108), in an embodiment, is integrated with a BMS of the battery pack (102). In an aspect, the control unit (108) is communicatively connected to the plurality of cells (106) and is configured to receive a plurality of cell parameters from the plurality of cells (106).
[00049] The control unit (108) comprises of suitable logic, circuitry interfaces, and/or code that is configured to receive a plurality of cell parameters of the plurality of cells (106). In an aspect, the control unit (108) may be configured to include a memory which may be implemented based on a Random Access Memory (RAM), a Read-Only Memory (ROM), a Hard Disk Drive (HDD), a storage server, and/or a Secure Digital (SD) card for storing the plurality of cell parameters. In an embodiment, the memory which comprises suitable logic, circuitry, interfaces, and/or code that is configured to store the set of instructions, which may be executed by the control unit (108).
[00050] In an aspect, the external load (104) refers to any equipment configured to draw current from the plurality of cells (106) of the battery pack (102). In an embodiment, the external load (104) is a motor of a powertrain of a vehicle. In an aspect, the external load (104) comprises of a controller (110) configured to be communicatively connected to the external load where the power is actually delivered. In an embodiment, the controller (110) is a motor controller.
[00051] In operation, the controller (110) is configured to control a plurality of parameters of the motor such as the torque required, current required, power required and the voltage required. The controller (110) is communicatively connected to the control unit (108) where it communicates the plurality of parameters of the motor. In an aspect, the controller (110) transmits a set current limit, actual current consumed, set torque, actual torque delivered, set voltage and actual voltage to the intermediate control unit (114).
[00052] The controller (110) comprises of suitable logic, circuitry interfaces, and/or code that is configured to receive a plurality of parameters of the external load (104). In an aspect, the controller (110) may be configured to include a memory which may be implemented based on a Random Access Memory (RAM), a Read-Only Memory (ROM), a Hard Disk Drive (HDD), a storage server, and/or a Secure Digital (SD) card for storing external load (104) related parameters. In an embodiment, the memory which comprises suitable logic, circuitry, interfaces, and/or code that is configured to store the set of instructions, which may be executed by the controller (110).
[00053] In operation, the control unit (108) is configured to receive a plurality of cell parameters from the plurality of cells (106). The plurality of cell parameters comprises at least one of a state of charge, a state of health, a current, a power, a voltage and a temperature of the plurality of cells (106). In an aspect, the state of charge of the plurality of cells (106) refers to the level of charge of the plurality of cells (106) with reference to its capacity as designated by a manufacturer of the plurality of cells (106), in essence the state of charge represents the amount of energy available in the plurality of cells (106). The state of health of the plurality of cells (106) refers to the ability of the plurality of cells (106) to retain the charge in comparison to its rated value, in essence the state of health indicates the level of degradation of the plurality of cells (106). The control unit (108) based on the received plurality of cell parameters, determines a dynamic threshold of the plurality of cells (106). The dynamic threshold is associated with the plurality of cell parameters. The dynamic threshold of the plurality of cells (106) comprises at least one of a current threshold, a power threshold and an energy threshold. The current threshold, power threshold and energy threshold determined by the control unit (108) is based on the available energy count in the plurality of cells (108) indicated by the plurality of cell parameters. The control unit (108) then regulates the supply of current from the plurality of cells (108) to the external load (104) upon satisfaction of a first set of pre-defined conditions, wherein the supply of current is regulated by a pre-defined factor. The current threshold, power threshold and energy threshold set by the control unit (108) is implemented in the plurality of cells (106) and accordingly the current, power and voltage supplied to the external load (104) is regulated by the control unit (108). The satisfaction of the first set of pre-defined conditions is when current and power supplied to the external load (104) exceeds the dynamic threshold of the plurality of cells (106). The satisfaction of the first set of pre-defined conditions requires regulation of the current, power and voltage supplied to the external load (104) to be in accordance with the determined dynamic threshold. The disclosed configuration of regulation of current supplied to the external load (104) by the control unit (108) ensures longer range, cycle life and durability of the battery pack (102).
[00054] In order to achieve a smooth operation and transition from the earlier current, voltage and power being supplied to the external load (104) to the dynamic threshold set by the control unit (108), the current is regulated by the pre-defined factor. The pre-defined factor is associated with a pre-defined derating value of the plurality of cells (106) and a temperature of the plurality of cells (106). The temperature of the plurality of cells (106) being provided by a plurality of temperature sensors disposed in the battery pack (102).
[00055] In an aspect, a plurality of temperature sensors or thermistors are disposed in pre-determined local hot spots of the plurality of cells (106) to effective measure the temperature in the plurality of cells (106) and convey the same in the event of overheating or thermal runaway. In an aspect, the plurality of temperature sensors are communicatively connected to the control unit (108).
[00056] In an aspect, the control unit (108) is configured to determine the dynamic threshold of the plurality of cells (106) over a pre-set period of time and accordingly regulate the supply of current from the plurality of cells (106) to the external load (104). The evaluation of the dynamic threshold after a pre-set period of time ensures effective monitoring of plurality of cell parameters and smoother transition between the new dynamic thresholds of the plurality of cells (106).
[00057] In an aspect, the system (100) for derating current in a battery pack (102) comprises of a DC-DC converter (112). The DC-DC converter (112) is an electromechanical device configured to convert the DC current received from the plurality of cells (106) of the battery pack (102) at a first voltage level to a second voltage level. The first voltage level is based on the plurality of cell parameters from the plurality of cells (106) of the battery pack. The second voltage level is based on the voltage requirements of the external load (104). In an embodiment, the DC-DC converter (112) comprises of an input-output port, one or more power switches, a pulse wave modulating controller and a filter unit.
[00058] In an aspect, the intermediate control unit (114) is communicatively connected to the control unit (108) of the battery pack (102) and the controller (110) of the external load (104). The intermediate control unit (114) based on the received plurality of cell parameters and the determined dynamic threshold from the control unit (108) configures the torque, power, current and voltage of the external load (104) based on the energy count available in the plurality of cells (106) of the battery pack (102). The intermediate control unit (114) also receives the torque, current and voltage requirements of the external load (104) and configures the external load (104) to deliver the torque, current and voltage based on the determined dynamic threshold of the plurality of cells (106) wherein the intermediate control unit (114) determines the new torque and current to be supplied to the external load (104). In an embodiment, the intermediate control unit (114) is a vehicle control unit.
[00059] The intermediate control unit (114) comprises of suitable logic, circuitry interfaces, and/or code that is configured to receive a plurality of parameters of the external load (104) as well as the plurality of cell parameters from the plurality of cells (106). In an aspect, the intermediate control unit (114) may be configured to include a memory which may be implemented based on a Random Access Memory (RAM), a Read-Only Memory (ROM), a Hard Disk Drive (HDD), a storage server, and/or a Secure Digital (SD) card for storing external load (104) related parameters and the plurality of cell parameters. In an embodiment, the memory which comprises suitable logic, circuitry, interfaces, and/or code that is configured to store the set of instructions, which may be executed by the intermediate control unit (114).
[00060] In an embodiment, the system (100) for derating current in a battery pack (102) comprises of a display unit. The display unit may be disposed in a instrument cluster of a vehicle, an electronic device of the user being a personal digital assistant or any other form of electronic instrument configured to serve as an interface between the system (100) and the operator or user of the battery pack (102). The display unit is communicatively connected to the control unit (108) and is configured to display at least one of the plurality of cell parameters of the plurality of cells (106) and the determined dynamic threshold.
[00061] Figure 2 illustrates a block diagram depicting one or more components of the system environment, in accordance with some embodiments of the present disclosure.
[00062] With reference to Figure 2, 202 denotes a regulating circuit, 204 denotes an analog front end unit, 206 denotes a cell balancing circuit, 208 denotes a CAN unit, 210 denotes a microcontroller, 212 denotes a communication gateway block, 214 denotes a rotor-stator assembly, 216 denotes high voltage terminals and 218 denotes an inverter.
[00063] For the sake of brevity, embodiments illustrated in Figure 2 shall be explained in relation to the embodiments explained in relation to Figure 1.
[00064] In an aspect, the battery pack (102) comprises of the plurality of cells (106), the regulating circuit (202), the analog front end unit (204), the cell balancing circuit (206), the control unit (108) and a CAN unit (208).
[00065] In an aspect, the intermediate control unit (114) comprises of a microcontroller (210) and a communication gateway block (212). The communication gateway block (212) comprises of an input-output port, a CAN controller and transceiver, a LIN controller and transceiver and an ethernet controller and transceiver.
[00066] In an aspect, the external load (104) comprises of a rotor-stator assembly, high voltage terminals (216), a controller (110) and an inverter (218).
[00067] In an aspect, the battery pack (102), the intermediate control unit (114) and the external load (104) are communicatively connected to each other.
[00068] In operation, the plurality of cells (106) represented in figure 2 by cell 1 to cell n, is at least one of electrically and communicatively connected to the analog front end unit (204). The plurality of cells (106) transmits the plurality of cell parameters to the analog front end unit (204). The plurality of cell parameters comprises at least one of voltage, temperature, current, state of charge, state of health and power of each cell of the plurality of cells (106).
[00069] The analog front end unit (204) is communicatively connected to the control unit (108). The analog front end unit (204) is configured to receive the plurality of cell parameters from the plurality of cells (106) and transmit the plurality of cell parameters to the control unit (108) through a dedicated communication channel. In an embodiment, the analog front end unit (204) is disposed between the plurality of cells (106) and the control unit (108). In an aspect, the analog front end unit (204) consolidates the plurality of cell parameters and supplies to the control unit (108). The analog front end unit (204) measures all the analog signals received from the plurality of cells (102) in the form of plurality of cell parameters. In an aspect, the analog front end unit (204) is communicatively connected to a plurality of current sensing units and plurality of temperature sensors disposed in the battery pack (102). In an embodiment, the analog front end unit (204) comprises of one or more resistors configured to balance cell voltages in the event of a detected electrical anomaly.
[00070] In an embodiment, the plurality of cell parameters are directly transmitted from the plurality of cells (106) to the control unit (108) through a dedicated communication channel. In an aspect, the dedicated communication channel being at least one of a full duplex communication and a half duplex communication. The half duplex communication being I2C and the full duplex communication being SPI.
[00071] The control unit (108) receives the plurality of cell parameters and determines a dynamic threshold. The dynamic threshold is determined based on the energy count available in the plurality of cells (106). The dynamic threshold comprises of at least one of a current threshold, a power threshold and an energy threshold and fault information pertaining to the plurality of cells (106). The fault information comprises of voltage imbalances, overcurrent, undercurrent, overheating aspect and other forms of electrical anomalies.
[00072] The control unit (108) based on the determined dynamic threshold regulates the current supplied from the plurality of cells (106) through the regulating circuit (202). The regulating circuit (202) is configured to receive an input from the control unit (108) to regulate the supply of current and regulate the supply of current from the plurality of cells (106) by the pre-defined factor.
[00073] The control unit (108) is additionally configured to balance cell imbalances in the plurality of cells through the cell balancing circuit (206).
[00074] In an embodiment, the analog front end unit (204) is electrically connected to the cell balancing circuit (206) and balances the imbalances in cell voltages in the plurality of cells (106) through the cell balancing circuit (206).The cell balancing circuit (206) is configured to regulate one or more cell voltages of the plurality of cells by the control unit (108) based on the received plurality of cell parameters.
[00075] In an aspect, the control unit (108) is communicatively connected to the intermediate control unit (114) and the external load (104) through the CAN unit (208). The at least one of a current threshold, a power threshold and an energy threshold and fault information pertaining to the plurality of cells (106) is transmitted from the control unit (108) to the CAN unit (208) which is then transmitted to the intermediate control unit (114) and the external load (104). The CAN unit (208) comprises of a controller and a transceiver wherein the CAN unit is configured to transmit a signal from the control unit (108) to the intermediate control unit (114) and the external load (104). The signal comprises of the determined dynamic threshold.
[00076] In an embodiment, the CAN unit refers to any form of communication unit wherein the communication channel being one of a wired and wireless communication. The CAN unit is configured to communicate the determined dynamic threshold through CAN, cellular, LAN, LIN, CAN, Wi-Fi, Bluetooth, infrared and other forms of communication through electromagnetic signals.
[00077] In operation, the transmitted dynamic threshold by the control unit (108) configures the external load (104) to operate within the safe operating limits set by the dynamic threshold. In an embodiment, the external load (104) is configured to operate within the safe operating limits defined by the dynamic threshold by the intermediate control unit (114).
[00078] In an embodiment, the modules, and sub-modules have been illustrated and explained to serve as examples and should not be considered limiting in any manner. It will be further appreciated that the variants of the above disclosed system elements, modules, and other features and functions, or alternatives thereof, may be combined to create other different systems or applications.
[00079] Figure 3 depicts a flowchart illustrating a method for derating current in a battery pack, in accordance with some embodiments of the present disclosure.
[00080] The method (300) starts at step 302 and proceeds to step 304. At step 304, the control unit (108) receives a pre-set plurality of cell parameters of the plurality of cells (106) disposed in the battery pack (102). The pre-set plurality of cell parameters comprises at least one of a peak current, a peak power and a peak torque. The pre-set plurality of cell parameters are provided by a manufacturer of the battery pack (102). The peak values of current, power and torque represent the maximum output in terms of current, power and torque the battery pack (102) is capable of delivering. The control unit (108) is at least one of communicatively and electrically connected to the plurality of cells (106).
[00081] At step 306, the control unit (108) configures the plurality of cells (106) to supply a pre-defined current limit to the external load (104) over a first pre-defined period of time, wherein the pre-defined current limit being associated with the pre-set plurality of cell parameters. In an aspect, the external load (104) is electrically connected to the plurality of cells (106). The pre-defined current limit is the peak current of the plurality of cells (106) of the battery pack (102). Continuous supply of peak current to the external load (104) would lead to faster degradation or shorter lifecycle of the battery pack (102) hence the peak current is only supplied during initial operation of the external load (104). During initial operation of the external load (104) such as starting the external load (104), the plurality of cells (106) are configured to supply the pre-set plurality of cell parameters to the external load. Further, the peak current is only supplied over a first pre-defined period of time to avoid unnecessary draining of the battery pack (102). Also, over initial starting the current, voltage and torque requirements of the external load (104) are considerably lower than the peak values thus making the supply of pre-set plurality of cell parameters to the external load (104) redundant. After supplying the pre-defined current limit to the external load (104) over the first pre-defined period of time, the method (300) moves to step 308. In an embodiment, the first pre-defined period of time being at least ten seconds.
[00082] At step 308, the control unit (108) receives a plurality of cell parameters from the plurality of cells (106). The plurality of cell parameters comprising at least one of a state of charge, a state of health, a current, a power, a voltage and a temperature of the plurality of cells (106). At step 308, the control unit (108) receives an estimate of the capacity of the plurality of cells (106) in terms of energy count or energy available in the battery pack (102) after the first pre-defined period of time. In an aspect, the energy count is coulomb counting performed to estimate the energy exiting the plurality of cells (106). The method (300) then proceeds to step 310.
[00083] At step 310, the control unit (108) determines a dynamic threshold of the plurality of cells (106) wherein the dynamic threshold of the plurality of cells (106) is associated with the plurality of cell parameters. The dynamic threshold comprises of at least one of a current threshold, a power threshold and an energy threshold determined based on the energy count of the plurality of cells (106), wherein the energy count being determined based on the plurality of cell parameters. At step 310, permissible limits of current, power and energy is set by the control unit (108) based on the available energy in the plurality of cells (106).
[00084] At step 312, the control unit (108) configures the plurality of cells (106) to regulate a supply of current to the external load (104) upon satisfaction of a first set of pre-defined conditions, wherein the current to the external load (104) is regulated by a pre-defined factor. The pre-defined factor is associated with a pre-defined derating value of the plurality of cells (106) and a temperature of the plurality of cells (106). In an aspect, the derating factor is an exponential function of temperature and the pre-defined derating value. In another aspect, the derating factor is an integral function of the current being consumed by the external load (104), the available state of charge and the energy limit associated with the state of charge of the plurality of cells (106).
[00085] The pre-defined derating value is a value furnished such that the peak limits of current, power and energy of the plurality of cells (106) are not violated and additionally, it permits a smooth operation of the external load (104) with modifications in current supplied permitting a smooth user experience.
[00086] The satisfaction of the first set of pre-defined conditions is when current and power supplied to the external load (104) exceeds the dynamic threshold of the plurality of cells (106). Upon satisfaction of the first set of pre-defined conditions, the current and power supplied to the external load (104) is decreased based on the pre-defined factor to be within the dynamic threshold limits.
[00087] The non-satisfaction of the first set of pre-defined conditions is when the current and power supplied to the external load (104) is below the dynamic threshold over a second pre-defined period of time. The current and power supplied to the external load (104) being less than the dynamic threshold leads to accumulation of energy in the battery pack (102), in this scenario the control unit is configured to again determine the dynamic threshold of the plurality of cells (106) after a second pre-defined period of time. Based on the new dynamic threshold, the first set of pre-defined conditions are modified. Further, due to new dynamic threshold limits, the external load (104) can now be supplied be a higher current, power and energy value and accordingly the current being supplied to the external load (104) is increased by the pre-defined factor. In an aspect, the pre-defined factor is based on an energy based degradation model for derating current in the plurality of cells (106). In an aspect, the increase in current by the pre-defined factor is termed as pro-active degradation. The method (300) ends at step 314.
[00088] Figure 4 depicts flowchart for implementation of an exemplary embodiment of a control unit, in accordance with some embodiments of the present disclosure.
[00089] For the sake of brevity, the flowchart (400) illustrated in Figure 4 is explained with reference to the method (300) in Figure 3. Figure 4 represents an exemplary embodiment of the present invention and explains the method for derating current in the battery pack (102) in terms of energy degradation model.
[00090] The flowchart (400) starts at step 402. Steps 404, 406 and 408 of figure 4 map with step 304, 306 and 308 of Figure 3. The dynamic threshold determined by the control unit (108) is determined in terms of Emax where Emax is indicative of an energy count of the plurality of cells (106) which represents the energy threshold of the plurality of cells (106).
[00091] At step 410, the control unit (108) determines a difference between the energy consumed by the external load (104) and the energy Emax as per the determined threshold. The energy being consumed (represented by Ecom) by the external load (104) represents the energy exiting the plurality of cells (106).
[00092] In the event, the energy consumed Ecom is greater than the energy threshold (Emax), the flowchart (400) proceeds to step 412. In the event the energy consumed (Ecom) is less than the energy threshold (Emax) the flowchart (400) proceeds to step 402 where it re-evaluates the dynamic threshold in terms of energy threshold (Emax).
[00093] At step 412, the control unit (108) is configured to regulate the supply of current or the energy exiting (Ecom) the plurality of cells (106) such that the energy consumed (Ecom) by the external load (104) is derated by a pre-defined derating factor to be within the precincts of the energy threshold (Emax). The flowchart (400) then proceeds to step 414.
[00094] At step 414, the derated value of energy consumed (Ecom) is supplied to the external load (104) where the energy consumed (Ecom) is based on the dynamic threshold comprising of energy threshold (Emax), power threshold and current threshold. The flowchart (400) then proceeds to step 416.
[00095] At step 416, the energy consumed (Ecom) by the external load (104) is again compared with the energy threshold (Emax) as per the dynamic threshold determined in step 408. In the event the energy consumed (Ecom) is less than the energy threshold (Emax), the flowchart proceeds to step 418. In the event, the energy consumed (Ecom) is still higher than the energy threshold (Emax) as per dynamic threshold, the flowchart (400) goes back to step 412 where the current supplied to the external load (104) is again derated based on the pre-defined factor.
[00096] At step 418, the control unit (108) calculates the energy recovered based on derating the current supplied by the battery pack (102). During operation of the external load (104) the external load (104) does not consistently draw current of the current threshold but it would fluctuate based on operating conditions whilst being within the current threshold defined by the dynamic threshold. The energy consumed (Emax) based on actual current consumed by the external load (104) would thus lead to slower degradation of charge of the battery pack (102) as would have been estimated in step 408. The real-time operating conditions of the external load (104) leads to an accumulation of energy represented as ΔE. The estimation of ΔE is done after the second pre-defined period of time since the step 416 where the energy consumed (Ecom) is less than the energy threshold (Emax). The accumulated or recovered energy ΔE is now added back to the energy count done in step 404 following which the dynamic threshold is re-evaluated by the control unit (108). In an aspect, the cycle time between consequent iterations of step 408 where the dynamic threshold is determined is done over the pre-set period of time. The flowchart (400) ends at step 420.
[00097] The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, and “one embodiment” mean “one or more (but not all) embodiments of the invention(s)” unless expressly specified otherwise. The terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless expressly specified otherwise. The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise.
[00098] The disclosed claimed limitations and the disclosure provided herein provides a system (100) and method (300) for derating currents in the battery pack (102) which achieves higher battery durability and longer cycle life of the battery pack (102). The control unit (108) as per the present disclosure determines a dynamic threshold based on a plurality of cell parameters of the plurality of cells (106) in the battery pack (102) in real-time, wherein the current supplied by the battery pack (102) is optimized based on the dynamic threshold determination. The present subject matter additionally addresses concerns of overheating, thermal runaway and short circuit in the battery pack (100)
[00099] Thus, the disclosed method (300) and system (100) tries to overcome the technical problem of thermal runaway, unintentional circulating currents and protection of the battery pack (102) by defining the safe operating limits of the battery pack (102). Additionally, the derating of the current is performed in a quick and effective manner to ensure smooth operation of the external load (104) conforming to automotive industry standards.
[000100] The present subject matter additionally facilitates effective battery pack (102) cooling by maintaining operating temperature of the battery pack (102) during battery pack (102) operation to be within the dynamic threshold determined by the control unit (108). The optimization of current, power and energy limits of the plurality of cells (106) in view of the dynamic threshold avoids instances of overheating which otherwise occur in the battery pack (102). For instance, when the battery pack (102) is configured to continuously supply its peak current, peak power and peak energy to the external load (104), the operating environment evidences the overheating and potential runaways occurring in the battery pack (102). The present subject matter addresses this technical problem persistent in conventional battery pack (102).
[000101] Thus, the claimed limitations overcome the aforementioned technical problems by providing a control unit (108) in the battery pack (102) which determines the dynamic threshold, regulates the current being supplied to the external load (104) and maintains a safe operating environment of the battery pack (102).
[000102] In light of the above-mentioned advantages and the technical advancements provided by the disclosed method and system, the claimed steps as discussed above are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies. Further, the claimed steps clearly bring an improvement in the functioning of the device itself as the claimed steps provide a technical solution to a technical problem.
[000103] A description of an embodiment with several components in communication with a other does not imply that all such components are required, On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention,
[000104] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter and is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.
[000105] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
[000106] The present disclosure may be realized in hardware, or a combination of hardware and software. The present disclosure may be realized in a centralized fashion, in at least one computer system, or in a distributed fashion, where different elements may be spread across several interconnected computer systems, a computer system or other apparatus adapted for carrying out the methods described herein may be suited. A combination of hardware and software may be a general-purpose computer system with a computer program that, when loaded and executed, may control the computer system such that it carries out the methods described herein. The present disclosure may be realized in hardware that comprises a portion of an integrated circuit that also performs other functions.
[000107] A person with ordinary skills in the art will appreciate that the systems, modules, and sub-modules have been illustrated and explained to serve as examples and should not be considered limiting in any manner. It will be further appreciated that the variants of the above disclosed system elements, modules, and other features and functions, or alternatives thereof, may be combined to create other different systems or applications.
[000108] Those skilled in the art will appreciate that any of the aforementioned steps and/or system modules may be suitably replaced, reordered, or removed, and additional steps and/or system modules may be inserted, depending on the needs of a particular application. In addition, the systems of the aforementioned embodiments may be implemented using a wide variety of suitable processes and system modules, and are not limited to any particular computer hardware, software, middleware, firmware, microcode, and the like. The claims can encompass embodiments for hardware and software, or a combination thereof.
[000109] While the present disclosure has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed, but that the present disclosure will include all embodiments falling within the scope of the appended claims.
List of Reference Numerals:
100 – System Environment
102 – Battery Pack
104 – External Load
106 – Plurality of Cells
108 – Control unit
110 – Controller
112 – DC-DC Converter
114 – Intermediate control unit
202 – Regulating circuit
204 – Analog Front End Unit
206 – Cell balancing circuit
208 – CAN unit
210 – Microcontroller
212 – Communication gateway block
214 – rotor and stator
216 – High Voltage Terminals
218 - Inverter
, Claims:We claim:
1. A system (100) for derating currents in a battery pack, (102) the system (100) comprising:
a plurality of cells (106);
an external load (104), the external load (104) being electrically connected to the plurality of cells (106); and
a control unit (108) the control unit (108) being communicatively connected to the plurality of cells (106) and the external load (104),
wherein the control unit (108) being configured to:
receive a plurality of cell parameters from the plurality of cells (106);
determine a dynamic threshold of the plurality of cells (106),
wherein the dynamic threshold being associated with the plurality of cell parameters;
regulate supply of current from the plurality of cells (106) to the external load (104) on satisfaction of a first set of pre-defined conditions,
wherein the supply of current being regulated by a pre-defined factor.

2. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the system (100) comprises a cell balancing circuit (206) configured to regulate one or more cell voltages of the plurality of cells (106) by the control unit (108) based on received plurality of cell parameters.

3. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the system (100) comprising of a regulating circuit (202) configured to:
receive an input from the control unit (108) to regulate the supply of current; and
regulate the supply of current from the plurality of cells (106) by the pre-defined factor.

4. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the plurality of cell parameters comprising at least one of a state of charge, a state of health, a current, a power, a voltage and a temperature of the plurality of cells (106).

5. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the dynamic threshold of the plurality of cells (106) being at least one of a current threshold, a power threshold and an energy threshold determined based on the plurality of cell parameters.

6. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the satisfaction of the first set of pre-defined conditions being when current and power supplied to the external load (104) exceeds the dynamic threshold of the plurality of cells (106).

7. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the pre-defined factor being associated with a pre-defined derating value of the plurality of cells (106) and a temperature of the plurality of cells (106).

8. The system (100) for derating currents in the battery pack (102) as claimed in claim 1, wherein the control unit (108) being configured to determine the dynamic threshold of the plurality of cells (106) over a pre-set period of time and accordingly regulate the supply of current from the plurality of cells (106) to the external load (104).

9. A method (300) for derating current in a battery pack (102), the method (300) comprising steps:
receiving (304), by a control unit (108), a pre-set plurality of cell parameters from a plurality of cells (106) disposed in the battery pack (102);
configuring (306), by the control unit (108), the plurality of cells (106) to supply a pre-defined current limit to an external load (104) over a first pre-defined period of time,
wherein the external load (104) being electrically connected to the plurality of cells (106), and
wherein the pre-defined current limit being associated with the pre-set plurality of cell parameters;
receiving (308), by the control unit (108), a plurality of cell parameters from the plurality of cells (106);
determining (310), by the control unit (108), a dynamic threshold of the plurality of cells (106),
wherein the dynamic threshold of the plurality of cells (106) being associated with the plurality of cell parameters; and
configuring (312), by the control unit (108), to regulate a supply of current of the plurality of cells (106) to the external load (104) on satisfaction of a first set of pre-defined conditions,
wherein the supply of current to the external load (104) being regulated by a pre-defined factor.

10. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the pre-set plurality of cell parameters comprises of a peak current, a peak power, a peak torque, and wherein the pre-defined current limit being the peak current.

11. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the plurality of cell parameters comprising at least one of a state of charge, a state of health, a current, a power, a voltage and a temperature of the plurality of cells (106).

12. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the dynamic threshold of the plurality of cells (1061) being at least one of a current threshold, a power threshold and an energy threshold determined based on an energy count of the plurality of cells (106), wherein the energy count being determined based on the plurality of cell parameters.

13. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the satisfaction of the first set of pre-defined conditions being when current and power supplied to the external load (104) exceeds the dynamic threshold of the plurality of cells (106).

14. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein upon non-satisfaction of the first set of pre-defined conditions where the current and power supplied to the external load (104) being below the dynamic threshold being over a second pre-defined period of time, the control unit (108) being configured to
determine a new dynamic threshold of the plurality of cells (106); and
modify the first set of pre-defined conditions based on the new dynamic threshold of the plurality of cells (106).

15. The method (300) for derating current in the battery pack (102) as claimed in claim 14, wherein the upon non-satisfaction of the first set of pre-defined conditions the control unit (108) configures the plurality of cells (106) to increase current and power supplied to the external load (104) by the pre-defined factor.

16. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the pre-defined factor being associated with a pre-defined derating value of the plurality of cells (106) and a temperature of the plurality of cells (106).

17. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the control unit (108) receiving the plurality of cell parameters from the plurality of cells (106) through a dedicated communication channel, wherein the dedicated communication channel being at least one of a half duplex communication and a full duplex communication.

18. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein an analog front end unit (204) being disposed between the plurality of cells (106) and control unit (108), wherein the analog front end unit (204) being configured to:
receive the plurality of cell parameters from the plurality of cells (106); and
transmit the plurality of cell parameters to the control unit (108) through a dedicated communication channel.

19. The method (300) for derating current in the battery pack (102) as claimed in claim 9, wherein the external load (104) being a motor of a powertrain of a vehicle.