METHOD AND SYSTEM FOR MANAGING POWER IN A VEHICLE

PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION

[001] The present invention relates to a vehicle running on electric power and more particularly to power management systems for such vehicles such as electric, hybrid vehicle and the like.

BACKGROUND OF THE INVENTION

[002] Today, technological development and research is directed towards producing environment-friendly vehicles keeping in mind the reduction of fossil fuels. Accordingly, electric vehicles are a more suitable option as they are non-polluting and reliable in terms of linear performance. Pollution has been a major concern and electric vehicles are quite a relief as they are far better for the environment. Whereas vehicles with combustion engines running on fuel such as diesel, petrol and the like burn fuel and emit harmful gases, electric vehicles produce fewer greenhouse gases and air pollution.

[003] Because of the associated economic and environmental benefits, petrol/diesel vehicles are getting replaced by Electric Vehicles (EVs) and hybrid vehicles. A hybrid vehicle runs on both combustion engine and battery depending upon the power needs while driving. An EV consist of mainly at least one battery, a Vehicle Control unit (VCU), a Motor control unit (MCU), a motor, and a wiring harness. Battery plays a major role in the vehicle performance, weight, and cost.

[004] A battery consists of mainly cells, interconnectors, and a BMS (a Battery Management System). Different types of cells are available in the market today. The cell selection of batteries is mainly based on their capacity and operating voltage that can meet the vehicle requirements if arranged in a particular configuration that is selected based on the size of the battery pack. The battery size and weight play a major role in the vehicle weight and cost as well as the battery capacity decides the range of the vehicle.

[005] It is already known to harness the power of the regeneration braking and use it as kinetic energy. Usually, the battery supplies energy to the motor during driving and accepts the regeneration current generated by the motor during braking or accelerating. Thereby, the battery selected for the vehicle, to both supply energy and accept regeneration power should be capable of meeting vehicle range and performance. However usually, such batteries fail to equally comply with the regeneration requirements. This is mostly because of the limitation of the battery of not accepting the regeneration current generated by the motor beyond its charging capacity. As a result of which, after the battery reaches its maximum charging capacity, it fails to accept the regeneration current for charging itself, and consequently, the regeneration current produced after the battery’s limit is reached, is wasted.

[006] Further, in the prior art, the current that the controller is pumping is not fully utilized by the main battery of the vehicle. This is because the battery charge rate of the main battery is usually less than the current supplied by the controller. For example, at any point of time, there can be chances, that though the current supplied by the controller is 60Amp, but the battery is only able to charge itself using 30 Amp. As a result, the rest of 30Amp is not utilised and wasted. And this wastage becomes more prominent when the regeneration current is also provided to the battery, but the battery is not able to accept more current than its charging capacity at any point of time.

[007] It can be appreciated that although the prior art tries to use the regeneration energy to charge the batteries of the vehicle and save energy, there is still wastage of energy as all of the regeneration energy available is not being harnessed/used.

[008] Thus, there is a need in the art for a power management system for a vehicle running on electric power, which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION

[009] In one aspect, the present invention is directed at vehicle including a power management system for managing power in the vehicle and a motor for providing traction to at least one wheel of the vehicle. The power management system includes a set of batteries and a plurality of control units. The set of batteries includes a power battery pack and a plurality of energy battery packs. The power battery pack includes a plurality of power cells configured to store all of the regeneration electric power from the motor during a vehicle regeneration state. The plurality of energy battery packs has energy cells for powering the motor. The plurality of control units control and manage the set of batteries and the motor, based upon a vehicle state of the vehicle.

[010] In an embodiment, the vehicle includes a communication module for enabling communication with and within the power management system. [011] In an embodiment, the plurality of control units includes a vehicle control unit and a motor control unit. The vehicle control unit manages and controls the set of batteries based upon the vehicle state of the vehicle. In an embodiment, the vehicle control unit manages and controls the set of batteries based upon inputs received from one or more sensors of the vehicle regarding the vehicle state. The motor control unit manages and controls the motor of the vehicle.

[012] In an embodiment, the energy cells provide electric power to the motor of the vehicle through the motor control unit during a vehicle drive mode.

[013] In an embodiment, the power battery pack receives and stores the complete regeneration electric power from the motor control unit. The power battery pack is configured to supply power to the energy cells using the regeneration electric power so received and stored depending upon a state of charge of at least one of the cells in the set of batteries of the vehicle.

[014] In an embodiment, the vehicle control unit is configured to change a mode of the energy cells and the power cells between a charging mode, a discharging mode and a sleep mode depending upon a connection status of the vehicle to an external charging device. In the charging mode, the cells receive power from an external source and in the discharging mode, the cells supply power to an external load. The vehicle control unit is configured to put the energy cells on the charging mode and the power cells on the sleep mode if the vehicle is connected to the external charging device. The vehicle control unit is configured to put the energy cells on the discharging mode and the power cells on the charging mode if the vehicle is disconnected from the external charging device. [015] In an embodiment, the motor control unit is configured to direct all of the regeneration electric power from the motor towards the power cells when the vehicle is in a braking mode.

[016] In an embodiment, the vehicle control unit is configured to discharge the power cells to charge the energy cells depending upon the state of charge of the energy cells. The vehicle control unit is configured to discharge the power cells to charge the energy cells when the difference in the state of charge of any two battery packs of the plurality of battery packs is more than a predefined value. The vehicle control unit is configured to charge the energy cells using power from power cells when the state of charge of at least one of the plurality of energy battery packs is below a predefined state of charge value. The predefined state of charge value is about 75-85%.

[017] In another aspect the invention provides a method for managing power in the vehicle. The method includes checking the vehicle state of the vehicle. The vehicle state may be one of a charging state, a driving state including a regeneration state, and a resting state. The vehicle state depends upon a power status of the vehicle and an external charging device connection status. The power status may be one of an ON condition and an OFF condition. The method includes putting on a charging mode via the vehicle control unit and charging via the external charging device at least one of the plurality of energy battery packs of the vehicle when the vehicle is in the charging state, wherein during the charging state, the power status is ON condition and the external charging device is connected to the vehicle. The method further includes putting on a sleep mode, via the vehicle control unit, the power battery pack when the vehicle is in the charging state, wherein the power battery pack while in the sleep mode neither supplies nor receives power. The method further includes putting on a discharging mode, via the vehicle control unit, the at least one of the plurality of energy battery packs when the vehicle is in the driving state, wherein while in the driving state, the power status is the ON condition and the external charging device is disconnected from the vehicle. The method further includes putting on charging mode, via the vehicle control unit, the power battery pack when the vehicle is in the driving state. The method further includes directing the complete regeneration power via the motor control unit towards and charging the power battery pack when the vehicle is in the driving state and a brake is applied to the vehicle. The regeneration power is produced as a result of the braking of the vehicle and the complete regeneration power so generated is directed towards the power battery pack.

[018] In an embodiment, wherein during the vehicle resting state when the power status is the OFF condition and the vehicle is not connected to the external charging device, the method further includes calculating a power imbalance value, via the vehicle control unit, by comparing a state of charge of each of the plurality of power battery packs and directing the power battery pack, via the vehicle control unit, to charge the at least one of the plurality of energy battery packs depending upon the power imbalance value. The method further includes charging at least one of the plurality of energy battery packs having a lower state of charge compared to a rest of the plurality of energy battery packs if the power imbalance value is greater than a predetermined value.

[019] In an embodiment, wherein when the power imbalance value is less than the predetermined value, the method further includes checking the state of charge of each of the plurality of battery packs and charging, via the power battery pack, at least one of the plurality of battery packs for which the state of charge is less than a predetermined state of charge value.

BRIEF DESCRIPTION OF THE DRAWINGS

[020] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figures 1 illustrates a vehicle including a system for managing power in the vehicle connectable to an external charging device, in accordance with an embodiment of the invention.

Figure 2 is a flow chart illustrating a method for managing power in the vehicle, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[021] The present invention relates to a system and a method for managing power in a vehicle. More particularly, the present invention relates to a power management system and a method in a vehicle that at least partly runs on electric power.

[022] Figures 1 illustrates a vehicle 200 connectable to an external charging device 300, in accordance with an embodiment of the invention. In various embodiments, the vehicle 200 may be an electrical vehicle or a hybrid electric vehicle. The vehicle 200 includes a power management system 100 for managing power in the vehicle 200 and a motor 210 for providing traction to at least one wheel 220 of the vehicle 200. The power management system 100 includes a plurality of control units 102 and 104 and a set of batteries 120 including a power battery pack 106 and a plurality of energy battery packs 110 including energy battery packs (110a and 110b). The power battery pack 106 includes a plurality of power cells and is configured to store all of the regeneration electric power from the motor 210 during a vehicle regeneration state. The plurality of energy battery packs (110a and 1 10b) includes energy cells for powering the motor 210.

[023] Each battery pack in the set of batteries 120 is a battery pack having cells such as Li-ion cells arranged in an array to achieve a desired power - current and voltage. The power battery pack 106 is a battery pack, which is capable of accepting high charge current. Each of the battery pack in the plurality of energy battery packs 1 10 is a battery pack including cells such as Li-ion cells arranged in an array to achieve the desired power as per requirement. In an embodiment, the vehicle 200 has more than two energy battery packs (1 10a and 110b).

[024] The plurality of control units (102 and 104) control and manage the set of batteries 120 and the motor 210 based upon a vehicle state of the vehicle 200.

[025] The vehicle state of the vehicle 200 may vary as per usage and user intervention and modification. The vehicle state includes a charging state, a driving state including the regeneration state and a resting/parked state (neither driving nor charging). In the charging state, a power status of the vehicle 200 is an ON condition and an external charging device connection status of the vehicle 200 is electrically connected to the external charging device 300 for charging the energy cells in the plurality of energy battery pack 1 10. In the driving state, the power status is still ON condition, and the external charging device connection status is disconnected as the vehicle 200 is disconnected from the external charging device 300. While in the driving state, when a driver of the vehicle 200 applies at least one brake of the vehicle 200 to slow down the vehicle 200, the vehicle 200 enters the regeneration state for the duration of application of the brake. In the resting/parked state, the power status is OFF condition, the external charging device connection status is not connected to an external charging device.

[026] In an embodiment, the vehicle 200 includes a communication module 130 for enabling communication with and within the power management system 100. For example, vehicle 200 has a Controller Area Network (CAN) bus-based communication system as the communication module 130. This bus allows many microcontrollers and different types of devices to communicate with each other in real time and also without a host computer.

[027] In an embodiment, the plurality of energy battery packs 110 and the power battery pack 106 are connected to the vehicle control unit 102 through the CAN bus. The motor control unit 104 and the vehicle control unit 102 are also connected through the CAN bus.

[028] In an embodiment, the plurality of control units (102 and 104) includes a vehicle control unit 102 and a motor control unit 104. The vehicle control unit 102 manages and controls the set of batteries 120 based on the vehicle state and upon inputs received from one or more sensors of the vehicle 200. The motor control unit 104 manages and controls the motor 210 of the vehicle 200.

[029] In an embodiment, the energy cells provide electric power to the motor 210 of the vehicle 200 through the motor control unit 104 during the driving state of the vehicle 200.

[030] In an embodiment, the power battery pack 106 receives and stores the complete regeneration electric power from the motor control unit 104. The power battery pack 106 is configured to supply power to the energy cells using the regeneration electric power so received and stored depending upon a state of charge of at least one of the cells in the set of batteries 120 of the vehicle 200.

[031] In an embodiment, the vehicle control unit 102, for managing and controlling the set of batteries 120, is configured to change a mode of the energy cells and the power cells between a charging mode, a discharging mode and a sleep mode, depending upon the vehicle state. During the charging mode, external power is supplied to the cells for charging. During the discharging mode, the cells supply power to an external load. During the sleep mode, the cells are idle, i.e., neither charging nor discharging.

[032] The vehicle control unit 102 is configured to put the energy cells on the charging mode and the power cells on the sleep mode if the vehicle 200 is in the charging state. The vehicle control unit 102 is configured to put the energy cells on the discharging mode and the power cells on the charging mode if the vehicle 200 is in the driving state. In an embodiment, in the vehicle state when the vehicle 200 is disconnected from the external charging device 300 and the power status is the ON condition, the vehicle control unit 102 puts the energy cells on the discharging mode to provide power to the motor 210 for providing traction to the at least one wheel 220 of the vehicle 200. Simultaneously, as and when the vehicle 200 is put in the driving state, the vehicle control unit 102 puts the power cells on the charging mode.

[033] In an embodiment, the motor control unit 104 is configured to direct all of the regeneration electric power from the motor 210 towards the power cells when the vehicle 200 is in the regeneration state. For example, when the vehicle 200 is in the driving state and a driver applies a brake to slow down the vehicle 200, a regenerative electric current is produced. The motor control unit 104 directs all the regeneration electric current so produced to charge the power cells of the power battery pack 106. The power battery pack 106 is dedicated for the purpose of handling regeneration current only since even during the charging state of the vehicle 200, the external charging device 300 does not charge the power cells in the power battery pack 106.

[034] In an embodiment, the vehicle control unit 102 is configured to discharge the power cells to charge the energy cells depending upon the state of charge of the energy cells. The vehicle control unit 102 is configured to discharge the power cells to charge the energy cells when the difference in the state of charge of any two battery packs of the plurality of battery packs 110 is more than a predefined value. While in the resting/parked state, the vehicle control unit 102 checks for a pack-to-pack imbalance among the plurality of energy battery packs 1 10. When the difference between the state of charge of any two battery packs in the plurality of battery packs 110 is more than the predefined value, the vehicle control unit 102 discharges the cells of the power battery pack 106 to charge the cells of an energy battery pack (110a or 110b) which has a lower state of charge. The predefined value may be between 10%-100%. A more precise range for the predetermined value is 10%-80%.

[035] For example, the predetermined value is 20% and the state of charge of the energy battery pack 1 10a is 30% and the energy battery pack 110b is 65%. Now when the vehicle 200 is in the resting state, the vehicle control unit 102 calculates the power imbalance between the energy battery packs 110a and 110b, which is 35% and more than the predetermined value 20%. Subsequently, the vehicle control unit 102 starts discharging the power cells in the power battery pack 106 to charge the energy cells of the energy battery pack 110a, 110b which is at a lower state of charge, i.e., the energy battery pack 1 10a.

The charging continues until the power imbalance reduces to a value less the predetermined value of 20%. The charging continues only until the vehicle 200 is in the resting state.

[036] In another embodiment, the vehicle control unit 102 is configured to charge the energy cells using power from power cells when the state of charge of at least one of the plurality of energy battery packs (110a and 1 10b) is below a predefined state of charge value. In an embodiment, the predefined state of charge value is about 75-85%. In another embodiment, the predefined state of charge value is about 65-75%. While in the resting/parked state, the vehicle control unit 102 checks the state of charge of each of the energy battery pack (110a and 110b) in the plurality of energy battery packs 110. When the state of charge of any one of the energy battery packs 110 is less than the predefined state of charge value, the vehicle control unit 102 discharges the cells of the power battery pack 106 to charge the cells of the low state of charge (SOC) battery pack identified.

[037] For example, the predetermined state of charge value is 65% and the state of charge of the energy battery pack 110a is 30% and the energy battery pack 110b is 65%. Now when the vehicle 200 is in the resting state, the vehicle control unit 102 checks the state of charge of the energy battery packs 110a and 110b. Since the state of charge of the energy battery pack 110 at 30% is less than the predetermined state of charge value, which is 65%, the vehicle control unit 102 starts discharging the power cells in the power battery pack 106 to charge the energy battery pack 110a. The charging continues until the state of charge of the energy battery pack 110a reaches about a full state of charge value of about 90-95%. The charging continues only until the vehicle 200 is in the resting state. [038] Figure 2 is a flow chart illustrating a method 400 for managing power in a vehicle 200, in accordance with an embodiment of the invention. The vehicle 200 comprising parts including a power battery pack 106, a plurality of energy battery packs (110a and 110b), a plurality of control units and a motor 210. The plurality of control units includes a vehicle control unit 102 and a motor control unit 104 and manages and controls the set of batteries and motor of the vehicle 200, respectively, depending upon a vehicle state. The power battery pack 106 is configured to charge the plurality of energy battery packs (110a and 1 10b). The plurality of energy battery packs (110a and 1 10b) is configured to power the motor 210. The motor 210 provides traction to at least one wheel of the vehicle 200 depending upon the vehicle state of the vehicle 200.

[039] The method 400 includes, at step 402, checking a vehicle state of the vehicle 200. In an embodiment, the method 400 includes continuously checking a vehicle state of the vehicle 200. The vehicle state is one of a charging state, a driving state including a regeneration state, and a resting state. The vehicle state depends upon a power status of the vehicle 200 and an external charging device connection status of an external charging device 300. The power status is either one of an ON condition and an OFF condition. The power status is generally changed by intervention of a user of the vehicle 200.

[040] When the vehicle 200 is in the charging state, during which the power status is the ON condition and the external charging device connection status is connected to the vehicle 200, the method 400 includes, performing steps 410 and 412. At step 410, the method includes putting on a charging mode and charging the plurality of energy battery packs (110a and 110b) of the vehicle 200. At step 412, the method includes putting on a sleep mode the power battery pack via the vehicle control unit 102. In an embodiment, at step 410, the method includes putting on a charging mode, via the vehicle control unit 102, and charging, via the external charging device 300 at least one of the plurality of energy battery packs (110a and 110b) of the vehicle 200. The plurality of energy battery packs (110a and 110b) are charged based on their state of charge. In an exemplary embodiment, only energy battery packs with state of charge less than 75% are charged. In another exemplary embodiment, energy battery packs with state of charge more than 90% are not charged.

[041] When the vehicle is not in the charging state, i.e., when the power status is in the ON condition and the vehicle is not connected to any external charging device, the method includes, at step 450, putting on charging mode the power battery pack 106. In an embodiment, the step 450 includes putting on charging mode, via the vehicle control unit 102, the power battery pack 106.

[042] When the vehicle 200 is in the driving state wherein the vehicle power status is in the ON condition and the external charging device connection status is disconnected from the vehicle 200, the method includes performing steps 460 and 462. At step 460, the method includes putting on the discharging mode, via the vehicle control unit 102, the plurality of energy battery packs (110a and 110b). During the driving mode the plurality of energy battery packs 110 provide power to the motor 210.

[043] When in the driving state, the vehicle enters the regeneration state, step 462 is performed. The vehicle enters the regeneration sate when a brake of the vehicle is applied to the vehicle. A regeneration power is produced as a result of application of the brake to the vehicle. At step 462, the method includes charging the power battery pack (106) using a regeneration electric power. In an embodiment, at step 462, the method includes directing the complete regeneration electric power towards the power battery pack (106) via the motor control unit (104) and charging the power battery pack (106) using the complete regeneration current.

[044] When the vehicle (200) is in the resting state, during which the power status of the vehicle (200) is in the OFF condition and the external charging device status is not connected to the external device, the method 400 includes performing steps 470 to 476. At step 470, power battery pack 106 is put in the discharging mode.

[045] At step 472, the method includes calculating a power imbalance value and checking a state of charge of each of the battery pack 110a, 110b in the energy battery packs 110. In an embodiment, the power imbalance is calculated via the vehicle control unit 102 by comparing a state of charge of each battery pack (110a, 110b, and so on) in the plurality of energy battery packs 110.

[046] In case of power imbalance, i.e. , when the difference between the state of charge of any two battery packs (110a or 110b) in the plurality of battery packs 110 is more than the predefined value, the method includes performing step 476. At step 476, the method includes discharging the cells of the power battery pack 106 to charge the cells of the energy battery packs 110. In an embodiment, at step 476, the method includes discharging the cells of the power battery pack 106 to charge the cells of an energy battery pack which has a lower state of charge. The predefined value may be between ten and hundred. A more precise range for the predetermined value is ten to eighty.

[047] When the state of charge of at least one of energy battery pack in the plurality of energy battery packs (110a and 110b) is below a predefined state of charge value, step 474 is performed. At step 474, the method includes charging the energy cells using power from power cells. In an embodiment, at step 476, the power from the power battery pack 106 is directed via the vehicle control unit 102 to charge the energy cells when the state of charge of at least one of the plurality of energy battery packs (110a and 110b) is below a predefined state of charge value. In an embodiment, the predefined state of charge value is about 75-85%. In another embodiment, the predefined state of charge value is about 65- 75%. While in the resting/parked state, the vehicle control unit 102 checks the state of charge of each of the energy battery pack (110a and 110b) in the plurality of energy battery packs 110. When the state of charge of any one of the energy battery packs (110a or 1 10b) is less than the predefined state of charge value, the vehicle control unit 102 discharges the cells of the power battery pack 106 to charge the cells of the low SOC battery pack identified.

[048] Advantageously, the system and method for managing power in the vehicle provided by the invention reduces the wastage of available regeneration power and provides for maximum utilisation of the regeneration power. The invention provides an extra driving range with a lower frequency of charge requirement of the vehicle.

[049] The invention also reduces occurrence of pack-to-pack imbalance because even in the resting or parked state, the imbalance is taken care of by the power battery pack. Similarly, the power battery pack also takes care of the issue of deep discharging by charging the battery packs with low state of charge in the rested or parked state of the vehicle.

[050] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and Y1 modification may be made without departing from the scope of the invention as defined in the following claims.