Claims:We claim
1. A battery system (130) for electric vehicle, with two or more RESS battery packs of different chemistries with different working voltages, to overcome the vehicle range anxiety without compromising the battery life, comprising of :
a vehicle transmission system (121), for performing vehicle operations;
atleast an electric motor (122), in direct communication with the said vehicle transmission system (121);
atleast a vehicle controller unit (123), which on its one end is in direct communication with the brake (126) and accelerator (127) system of the vehicle, wherein said vehicle controller unit (123) at its other end is in direct communication with the electric motor (122);
atleast a inverter system (124), connected to the said vehicle controller unit (123); characterized in that,
a plurality of RESS packs (128a, 128b), connected in direct communication with the said inverter system (124), wherein said each of the RESS pack (128a, 128b) is provided with a battery management system (129a, 129b), wherein said each of the RESS pack (128a, 128b) connected to the inverter system (124) is of different chemistry with different working voltages, wherein said each of the RESS pack (128a, 128b) is connected to the said inverter system (124) by means of a plurality of electronic switches (131a, 131b);
a plurality of CAN communication systems (132a, 132b), connecting the said each of the battery management system (129a, 129b) in the RESS packs (128a, 128b) with the vehicle controller (123); and
atleast an electronic control unit (133), connecting the said vehicle controller unit (123) and said each of the electronic switch (131a, 131b).
wherein said electronic vehicle controller unit (123) switches on the appropriate electronic switch (131a, 131b) to connect specific RESS pack (128a, 128b) to the electrical bus of the vehicle based on battery parameters and on the instantaneous power requirement from vehicle controller unit (123) to achieve optimal performance from the energy storage system.

2. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said plurality of RESS packs (128a, 128b) with different chemistries is selected from lithium-ion based RESS battery packs.

3. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said plurality of RESS packs (128a, 128b) with different chemistries are selected from Lithium Nickel Manganese Cobalt Oxide (NMC), lithium ferrous phosphate (LFP), lithium-titanate-oxide (LTO), Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Cobalt Aluminum Oxide (NCA), and/or combinations thereof.

4. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said each of the electronic switch (131a, 131b) is placed in series to the positive terminal of the each RESS battery pack (128a, 128b) and the other terminal of each of the electronic switch (131a, 131b) is connected to the positive terminal of the said inverter system (124), negative terminals of all RESS battery packs (128a, 128b) are connected to the negative terminal of the inverter system (124).

5. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said of the each RESS battery pack (128a, 128b) is provided with a battery management system (BMS) (129a, 129b) and a centralized battery system controller communicating with every BMS (129a, 129b) of the said plurality of RESS battery packs (128a, 128b).

6. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said plurality of RESS packs (128a, 128b) of different chemistry with different working voltages are connected to the electrical bus of vehicle through an electro-mechanical relays.

7. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein said battery parameters includes but not limited to SOC, SOH, temperature of each of the battery, charge/discharge C-rate requirement of RESS, and power requirement from battery system.

8. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein the required energy capacity of vehicle battery system will be realized using the plurality of RESS battery packs (128a, 128b) involving different chemistries, power requirement are divided in proportion among said different RESS packs of different chemistries according to their capacity and run time.

9. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein sizing of different RESS battery packs for energy rating is arrived based on the detailed vehicle system level simulations.

10. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein logics to operate the said electronic control unit (133) is developed for providing high power from RESS battery pack of one chemistry and continuous power from RESS battery pack of another chemistry.

11. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein implementation of the said logics could be realized with a dedicated battery system controller which communicates with individual BMS (129a, 129b) of each of the RESS battery pack (128a, 128b) as well as vehicle controller (123).

12. The battery system for electric vehicle with two or more RESS battery packs of different chemistries, as claimed in claim 1, wherein the logics is implemented as a part of one of the BMS units of the RESS pack which would communicate with the said vehicle controller unit and other BMS units of the other RESS battery packs.

, Description:Field of Invention
The present invention relates generally to the field of batteries and battery modules. More specifically, the present disclosure relates to battery system for electrical vehicles with different chemistries and switching method thereof.
Background of the Invention
There is a growing need for the electrification of the transportation industry. Various strategies have emerged in the quest to develop commercially viable, energy advantageous vehicles that use electrical energy in full or in part to propel the vehicle. A vehicle that uses one or more battery systems for supporting propulsion, start/stop, and/or regenerative braking functions is referred to as an electrical vehicle. The term “electric vehicle” as used herein, includes vehicles having an electric motor for vehicle propulsion, such as battery electric vehicles (BEV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEV). Of great interest in the electrical vehicle is the way in which electrical energy is stored, controlled, and replenished in these different strategies. In addition, the cost and efficiency of storing and generating electrical power to run electrical vehicles has become increasingly important.

A “start-stop vehicle” is defined as a vehicle that disables the combustion engine when the vehicle is stopped and utilizes a battery (energy storage) system to continue powering electrical components onboard the vehicle, including the entertainment system, navigation, lights, or other electronics, as well as to restart the engine when propulsion is desired.
A major concern for batteries in electric vehicles is the ‘range anxiety,’ or the electric driving range per charge. However, other major concerns of manufacturers include calendar/cycling life, low temperature performance, safety, and cost. The result of balancing these concerns results in battery manufacturers generally compromising the cell design to achieve increased power capability at the expense of reduced energy density of the battery. This translates to reduced driving range per charge, lower abuse tolerance, and higher cell costs.
In the past, various manners of storing and providing electrical energy to drive an electrical load, such as an electrical driving motor, have been proposed. Batteries are Re-chargeable Energy Storage System (RESS) used to store and release energy in either a slow or a quick manner depending on the need. Batteries can have many different performance, or design, ratings to assist a user in matching the battery to an application. The application need may be in terms of power (rate), total energy (capacity), quantity of cycling, depth of cycling, thermal characteristics, impedance, etc. or some combination of these design ratings. There are nearly always tradeoffs between the different choices of design ratings. For example, a long cycle life battery is typically costly and heavy. A high-volume consumer type battery can be inexpensive, but is typically neither high-power nor high cycling. For an EV application, there may be different demands on a battery performance that are not satisfied in a single given design. For example, one battery design may provide sufficient power for acceleration needs, but insufficient energy for extended use. While a combination of a high-energy battery with a high-power battery provides sufficient electrical resources. Different types of batteries, including lead-acid, lithium, nickel cadmium (Ni—Cd) and nickel metal hydride (Ni—MH), have been used in the past to drive electric vehicles. However, each type of battery has unique advantages and disadvantages.
Lead-acid batteries provide a high burst of power when required and also they can provide a large currents sufficient to accelerate and drive electrical loads, such as electrical motors and engines in vehicles. In particular, a burst of power is generally required to overcome stationary friction and the inertia of a stationary electrically driven vehicle, as well as for acceleration. However, lead-acid batteries suffer from the disadvantage of having low energy density, meaning that the energy provided per unit volume is low. Likewise, lead-acid batteries have relatively low specific energy, meaning that a relatively large mass is needed to store a substantial quantity of energy.
By contrast, lithium-based batteries, such as lithium batteries having anodes or negative electrodes of lithium metal or alloy, have higher energy density and specific energy characteristics than lead or nickel based electrochemical cells. For higher power delivery requirements we would need to use a power cell, which is expensive and needs to be well thermally managed. Furthermore, to prevent degradation, lithium based cells require thermal management techniques to maintain the battery at an acceptable temperature, such as -20° C to a maximum of 60° C. Power bursts in lithium ion cells generally generate larger amounts of heat energy, which, if not managed properly, can degrade the battery.
Therefore, in an electrical vehicle, it is desirable to have an energy storage device which has a high energy density, so that a minimum volume is occupied by the energy storage device, as well as a high specific energy, so that minimum weight is transported along with the vehicle. However, it is also desirable to have an energy storage device which can provide large bursts of power. It is noted that attempts have been made to redesign rechargeable lithium batteries to be able to provide higher currents, but this led to lower specific energies and lower energy densities of such battery devices.
EVs typically use Re-chargeable Energy Storage System (RESS) or batteries involving a single chemistry, in such cases there are challenges in meeting all the performance and reliability parameters such as Power, range, size, weight, life & cost. However, industry has not yet found a battery technology that is sufficiently low cost and durable to achieve widespread commercialization and consumer acceptance of these vehicles.
Therefore, there remains a desperate need in the art for a cost-effective and durable energy storage system for EVs.
United states patent 10766368 provides a system and method for dual function battery comprising of an energy storage system for supporting dual electrical functions of a vehicle includes an energy storage unit having a plurality of energy storage modules connected in series, a plurality of sensing units for sensing state of charges of the plurality of energy storage modules, and a pair of primary voltage terminals. The series connected plurality of energy storage modules is connectable across the pair of primary voltage terminals during a key-on state of the vehicle to supply energy storage power at a first voltage level to support primary electrical functions of the vehicle. The energy storage system is further configured to select a subset of the plurality of energy storage modules during a key-off state of the vehicle to connect across a pair of secondary voltage terminals using a switch network to supply energy storage power at a second voltage level.
United States patent application 20050285559 discloses a dual battery vehicle electrical switchable system for a vehicle having an engine. The vehicle comprises a first load and a second load. The vehicle is switchable between an ON state in which the engine is running, an OFF state in which the engine is not running and a START state, in which the first load requires power. The system comprises a first battery arranged to provide power to the first load and a second battery arranged to provide power to the second load. A switch is provided between the first battery and the second battery and control means is arranged to open the switch only when the vehicle is in the OFF state. A connection system is also provided having a plurality of output terminals for connection to a plurality of primary and secondary loads and two input terminals for connection to the first and second batteries respectively.
United States Patent 6323608 relates to a dual voltage battery for a motor vehicle capable of powering an automobile system having electrical equipment that requires different supply voltage. The battery allows idle stop, assisted drive and regeneration to be performed more efficiently by cooperative control of a controller and a DC/DC converter. Commonly performed external powering and starting can also be carried out if the battery has expired. The single dual-voltage battery is obtained by equipping a 12-V battery with a 24-V battery of a different type and adapted to supply power to respective electrical components. The 12-V battery unit is provided with a charging controllable DC/DC converter or downverter. The ancillary battery condition is monitored and controlled. External powering and starting is facilitated by using an ultracapacitor as the ancillary battery. The battery can be used with a single relay.
United States patent US6909201 provides a dual voltage architecture for automotive electrical system includes a generator for generating a first nominal voltage on a first voltage bus and a bi-directional DC/DC converter for converting the first nominal voltage to a second nominal voltage on a second voltage bus, the second nominal voltage being lower than said first nominal voltage. A battery is coupled to the first voltage bus and selectably coupled to the second voltage bus, and is capable of supplying power to loads on both the first voltage bus and the second voltage bus.
None of the existing energy storage systems have attempted to use batteries with different chemistries, if at all an energy system with batteries of different chemistries are considered, each RESS would have differing terminal voltages leading to difficulties in parallel operation of RESS with different working voltage windows. Hence a sort of compromised solution with a single chemistry is considered practically for applications currently which reasonably meets various system requirements such as top speed, range, power, weight, life cost etc. in spite of the challenges highlighted above.
The present invention is proposed to overcome the challenges where dual or more RESS involving different chemistry for individual RESS could be realized to meet the above criteria. The present invention focusses on relieving the limitation of using RESS with single chemistry thereby providing a more optimal solution in terms of performance, life etc. The present invention proposes to realize the vehicle energy requirement with two or more RESS whose working voltages differ due to the cells of different chemistries. The battery system of present invention uses one or more RESS packs of different chemistries in a vehicle to overcome the range anxiety issue, without compromising the battery Life. The present invention also provides an efficient switching technique that helps in choosing the appropriate RESS packs such that cells of a single pack are not detoriated faster. By this we will be able to achieve a higher target range with single time charge of both or multiple RESS packs. The battery packs with different chemistries and switching technique of the present invention can be used on any electric vehicle, more particularly in two wheelers where RESS packs are more compact & portable, where this kind of techniques are much needed.
Objects of the Invention:
The main object of the present invention is to provide a battery system with different chemistries for electric vehicle which focusses on relieving the limitation of using RESS with single chemistry thereby providing a more optimal solution in terms of battery performance and life.
The primary object of the present invention to provide a battery system which uses RESS packs of different chemistries in an electric vehicle to overcome the range anxiety issue, without compromising the battery life.
It is another object of the present invention to provide a battery system which uses RESS packs of different chemistries and switching method which automatically realizes the vehicle energy requirement with two or more RESS whose working voltages differ due to the cells of different chemistries.
Still another object of the present invention is to provide a battery system with different chemistries and efficient switching technique that helps in choosing the appropriate RESS packs such that cells of a single pack are not detoriated faster.
It is another object of the present invention is to provide a battery system with different chemistries which enables to achieve a higher target range with single time charge of one or more RESS packs.
It is another object of the present invention to provide a battery system with different chemistries and switching technique which can be used on any electric vehicle.
Although the present invention is mainly designed as a battery system with two or more RESS packs of different chemistries for two wheeler battery which are more compact and portable, it goes without saying that the present invention can be applied and adapted for battery packs with more than two or multiple RESS of different chemistries adopting the same switching techniques as disclosed in the present invention and are also applicable to all types of electric vehicles.
SUMMARY OF THE INVENTION
From the above discussion of the background, it is apparent that the basic concept of battery system with RESS packs of single chemistry is widely present in the state of the art technology. The present invention focusses on relieving the limitation of using RESS packs with single chemistry thereby providing a more optimal solution in terms of performance, life etc. The present invention provides a battery system for electric vehicle, which uses two or more RESS battery packs of different chemistries with different working voltages, to overcome the vehicle range anxiety without compromising the battery life, comprising of : a vehicle transmission system; at least an electric motor, in direct communication with the said vehicle transmission system; atleast a vehicle controller unit, which is in direct communication with the electric motor; atleast a inverter system, connected to the said vehicle controller unit; characterized in that, a plurality of RESS packs, connected in direct communication with the said inverter system, wherein said each of the RESS pack connected to the inverter system is of different chemistry with different working voltages, wherein said each of the RESS pack is connected to the said inverter system by means of an electronic switch; a plurality of CAN communication systems; and atleast an electronic control unit, connecting the said vehicle controller unit and said each of the electronic switch.
In the preferred embodiment of the present invention, wherein said each of the RESS pack is provided with a battery management system.
In the preferred embodiment of the present invention, wherein said plurality of RESS packs with different chemistries is selected from lithium-ion based RESS battery packs.
In the preferred embodiment of the present invention, wherein said each of the electronic switch is placed in series to the positive terminal of the each RESS battery pack and the other terminal of each of the electronic switch is connected to the positive terminal of the said inverter system. Negative terminals of all RESS battery packs are connected to the negative terminal of the inverter system, each RESS battery pack is provided with a battery management system (BMS) and a centralized battery system controller communicating with every BMS of all RESSs.
The present invention proposes to realize the vehicle energy requirement with two or more RESS whose working voltages differ due to the cells of different chemistries. The battery system of present invention uses one or more RESS packs of different chemistries in a vehicle to overcome the range anxiety issue, without compromising the battery Life. The present invention also provides an efficient switching technique that helps in choosing the appropriate RESS packs such that cells of a single pack are not detoriated faster.
In an embodiment of the present invention, wherein said electronic vehicle controller unit turns on the appropriate electronic switch to connect specific RESS pack to the electrical bus of the vehicle based on parameters and/or status of each RESS pack and also based on the instantaneous power requirement from battery system to achieve optimal performance from the energy storage system. Depending of vehicle system requirement, a particular RESS pack will be selected at an instant to be connected to the electrical bus of vehicle based on various factors such as power demand from battery, SOC as well as SOH of each RESS, charge/discharge C-rate requirement of RESS, etc. By this we will be able to achieve a higher target range with single time charge of both or multiple RESS packs.
In the preferred embodiment of the present invention, sizing of different RESS battery packs for energy rating is arrived based on the detailed vehicle system level simulations.
In an embodiment of the present invention, logics to operate the electronic control unit can be developed providing high power from RESS battery pack of one chemistry and continuous power from RESS battery pack of another chemistry, balanced and long life by appropriate strategy of selection of RESS based on SOC / SOH / power level and best range. Implementation of the said logics could be realized with a dedicated battery system controller which communicates with individual BMS of each of the RESS battery pack as well as vehicle controller.
Other features and advantages of embodiments will be apparent from the accompanying drawings and from the detailed description that follows.
Brief Description of the Drawings
Fig.1 represents electric vehicle architecture platform with RESS battery pack of single chemistry as existing in the prior-art.
Fig. 2 represents electric vehicle architecture platform supporting two RESS battery pack of different chemistries with different working voltages and switching control method thereof in accordance with the present invention.
Fig. 3 represents electric vehicle architecture platform supporting three RESS battery pack of different chemistries with different working voltages and switching control method thereof in accordance with the present invention.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concept of the term appropriately to describe its own invention in the best way. The present invention should be construed as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, it should be understood that equivalents and modifications are possible.
Detailed Description of the Invention with Respect to the Drawings
The present invention as embodied by "Electric vehicle battery system with different chemistries and switching method thereof" succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/ modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The term “electric vehicle” or “EV” as used herein, includes vehicles having an electric motor for vehicle propulsion, such as battery electric vehicles (BEV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEV).
Fig. 1 shows the schematic representation of the existing EV architecture platform (120) supporting single RESS battery pack consisting of a single chosen chemistry. It comprises of a inverter system (124) with its one end in direct communication with the single chemistry RESS pack (125) and at its other end connected in series to the vehicle controller system (123), electric motor (122) and vehicle transmission (121), for controlling the vehicle operations such as brake, accelerator etc. When RESS packs (125) of similar capacity/ chemistry is used as shown in Fig.1, the parallel or series operation can be done easily. But when RESS packs of different chemistries and capacity/sizes are used, due to difference in the working voltage of different chemistries RESS packs, the controller will not be able to function with different working voltage windows.
The present invention focusses on relieving the limitation of using RESS with single chemistry thereby providing a more optimal solution in terms of battery performance, battery life etc. The present invention proposes to realize the vehicle energy requirement with two or more RESS battery packs whose working voltages differ due to the cells of different chemistries.
The present invention provides a battery system for electric vehicle (130), which uses two or more RESS battery packs of different chemistries with different working voltages, to overcome the vehicle range anxiety without compromising the battery life, comprising of : a vehicle transmission system (121), for performing vehicle operations; at least an electric motor (122), in direct communication with the said vehicle transmission system (121); atleast a vehicle controller unit (123), which on its one end is in direct communication with the brake (126) and accelerator (127) system of the vehicle, wherein said vehicle controller unit (123) at its other end is in direct communication with the said electric motor (122); atleast a inverter system (124), connected to the said vehicle controller unit (123); characterized in that, a plurality of RESS packs (128a,128b), connected in direct communication with the said inverter system (124), wherein said each of the RESS pack (128a,128b) is provided with a battery management system (129a,129b), wherein said each of the RESS pack (128a,128b) connected to the inverter system (124) is of different chemistry with different working voltages, wherein said plurality of RESS packs (128a,128b) is connected to the said inverter system (124) by means of a plurality of electronic switch (131a,131b); a plurality of CAN communication systems (132a,132b), connecting the said each of the battery management system (129a,129b) in the RESS pack with the vehicle controller; and atleast an electronic control unit (133), connecting the said vehicle controller unit (123) and said each of the electronic switch (131a,131b).
In the preferred embodiment of the present invention, wherein said plurality of RESS packs (128a, 128b) with different chemistries is selected from lithium-ion based RESS battery packs. In particular, RESS packs (128a,128b) with different chemistries are selected from Lithium Nickel Manganese Cobalt Oxide (NMC), lithium ferrous phosphate (LFP), lithium-titanate-oxide (LTO), Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Cobalt Aluminum Oxide (NCA), and/or combinations thereof.
In the preferred embodiment of the present invention, wherein said plurality of RESS packs (128a,128b) of different chemistry with different working voltages are connected to the electrical bus of vehicle through a plurality of electronic switches (131a,131b). Wherein said each of the electronic switch (131a, 131b) is placed in series to the positive terminal of the each RESS battery pack (128a, 128b) and the other terminal of each of the electronic switch (131a, 131b) is connected to the positive terminal of the said inverter system (124). Negative terminals of all RESS battery packs (128a,128b) are connected to the negative terminal of the inverter system (124), each RESS battery pack is provided with a battery management system (BMS) (129a,129b) and a centralized battery system (not shown) controller communicating with every BMS of all RESSs (128a,128b).
In an embodiment of the present invention, wherein said plurality of RESS packs (128a, 128b) of different chemistry with different working voltages are connected to the electrical bus of vehicle through an electro-mechanical relays.
In the preferred embodiment of the present invention, wherein said electronic switch (131a, 131b) could be a MOSFET with appropriate current rating typically controlled by a driver IC or it could be a MOSFET with in-built protection mechanisms for higher reliability such as PROFET, a Protected MOSFET, offering protection against overvoltage, short circuit, excessive temperature etc.
In the preferred embodiment of the present invention, based on battery parameters such as SOC, SOH, temperature of each of the battery as well as power requirement from battery system, centralized battery system controller identifies the RESS pack most appropriate to be used at a given instant and turns on the electronic switch in series to appropriate RESS.
In an embodiment of the present invention, wherein said electronic vehicle controller unit (123) turns on the appropriate electronic switch (131a, 131b) to connect specific RESS pack (128a, 128b) to the electrical bus of the vehicle based on parameters and/or status of each RESS pack and also based on the instantaneous power requirement to achieve optimal performance from the energy storage system. Depending on vehicle system requirement, a particular RESS pack (128a, 128b) will be selected at an instant to be connected to the electrical bus of vehicle based on various factors such as power demand from battery, SOC as well as SOH of each RESS, charge/discharge C-rate requirement of RESS, etc.
In the preferred embodiment of the present invention, wherein the required energy capacity of vehicle battery system will be realized using two or more RESS packs (128a, 128b) involving different chemistries. For say about 100% of total run duration system capacity, RESS/ batterypack with one chemistry could be considered for around 30% would be for Peak power whereas rest 70% would be for continuous power. Similarly in case of more than two RESS battery packs (128a, 128b) of different chemistries are involved, then power requirement are divided in proportion among those different RESS packs of different chemistries according to their capacity and run time.
Such a combination would facilitate achieving maximum power using RESS pack of one chemistry whenever required and rest of the time, RESS with another chemistry could be used. Thus the limitation of maximum power and life expectancy for the complete battery system could be resolved considering the combination of two or more RESSs packs with different chemistries. Since some batteries are expected to operate for lower duration compared to other battery chemistries, overall life of battery system is balanced. By such balancing based on RESS packs of different chemistries, the space constraint could be avoided. Also by such division RESS battery packs fitment would be ideal.
In the preferred embodiment of the present invention, Wherein said Li-ion batteries for RESS packs (128a,128b) of two different chemistries selected are Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium ferrous phosphate (LFP).
NMC has a typical charge and discharge rating of 0.5C and 1C; peak charge and discharge rates of 1C and 3C for a short duration respectively. While LFP chemistry has a typical charge and discharge rating of 0.5C and 1C respectively, whereas Peak Charge and discharge rates of 1C and 2C or 3C respectively. Also, NMC has a typical life of 1000 cycles (limiting the 85% or 90% depth of discharge would improve the lifecycles with reduction in the usable capacity) while LFP chemistry would provide for 2000 similar cycles typically, which could increase considering the DOD% & usable capacity.
If RESS pack Li-ion batteries of single chemistry only with NMC chemistry is alone selected for a given application, continuous maximum power delivered would be better than that of LFP chemistry, however, life would be inferior to the RESS battery pack with LFP chemistry. In case, RESS pack Li-ion batteries of single chemistry with LFP chemistry is used for entire energy requirement, life of RESS would be far better (corresponding to 2000 cycles) than that of RESS with NMC chemistry whereas the continuous maximum power that could be realized from the RESS with LFP chemistry would be significantly less compared to RESS using NMC chemistry. Therefore in such cases, due to limitation of use of single chemistry to realize battery system, compromises are made in terms of parameters such as maximum power, life etc.
In the preferred embodiment of the present invention, RESS battery pack (128a,128b) with specific chemistry is operated based on factors, including but not limited to, power demand, SOC/SOH parameters of RESSs, mode of operation by battery i.e. discharge mode or charge mode (regenerative braking).
In the preferred embodiment of the present invention, sizing of different RESS battery packs (128a, 128b) for energy rating is arrived based on the detailed vehicle system level simulations. Further based on environmental factors and battery parameters, it is possible to ensure safety of RESS battery packs following the conventional practices.
In an embodiment of the present invention, in case of higher power requirement, more than 2 RESS battery packs with appropriate chemistry could be combined to the battery system. For instant use of 3 different chemistries for three different RESS battery packs (135a, 135b, 135c) is shown in Fig 3. In this case, maximum continuous power would be taken care for by a RESS with a specific chemistry, peak power requirement for short duration would be addressed by another chemistry meant for power application where the continuous C-rates are generally like 4C or 6C with peak C-rates up to 10C to 15C, which would also require good thermal dissipation for optimal performance and life requirement would be addressed by RESS with relevant chemistry.
In particular, RESS packs (135a,135b,135c) with different chemistries are selected from Lithium Nickel Manganese Cobalt Oxide (NMC), lithium ferrous phosphate (LFP), lithium-titanate-oxide (LTO), Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Cobalt Aluminum Oxide (NCA), and/or combinations thereof.
In the preferred embodiment of the present invention, sizing of energy capacity of the said RESS battery packs could be arrived at by appropriate vehicle level simulations for relevant scenarios.
In an embodiment of the present invention, wherein more than three or multiple RESS battery packs (135a,135b,135c) with different chemistries can also be incorporated into the battery system with similar electronic switching (131a,131b) system to meet specific vehicle requirements ensuring battery performance and life requirements. Logics to ensure a balanced life for the multiple RESS battery packs (135a,135b,135c) is assured by appropriate duty to relevant battery based on SOH parameter in addition to SOC parameter of RESS battery packs.
In an embodiment of the present invention, logics to operate the electronic control unit (133) can be developed which provides for high power from RESS battery pack of one chemistry and continuous power from RESS battery pack of another chemistry, balanced and long life by appropriate strategy of selection of RESS based on SOC / SOH / power level and best range. Implementation of the said logics could be realized with a dedicated battery system controller which communicates with individual BMS of each of the RESS battery pack as well as vehicle controller or alternatively, the logics could be implemented as a part of one of the BMS units corresponding RESSs which would also communicate with vehicle controller and other BMS units. Alternatively, various options could be considered to integrate the roles of individual BMS units and controller for overall battery system with fewer controllers. These logics can be changed depending on the cell performance characteristics and test results, which could be based on the best SoC % & SoH %.
Based on specific performance behavior expected from battery system, sizing of RESS of different chemistries as well as logics to operate individual RESS could be arrived at by experts in the art.
EXAMPLE 1
The present invention focusses on relieving the limitation of using RESS with single chemistry thereby providing a more optimal solution in terms of battery performance, battery life, etc., The present invention provides a battery system (130) for electric vehicle, which uses two or more RESS battery packs of different chemistries with different working voltages, to overcome the vehicle range anxiety without compromising the battery life, comprising of : a vehicle transmission system (121) which is in direct communication with an electric motor (122). The said electric motor (122) is connected to the vehicle controller unit (123) at its one end. Said vehicle controller unit (123) at its one end is in direct communication with the brake (126) and accelerator (127) system of the vehicle and at its other end is in direct communication with a inverter system (124). The inverter system (124) is in direct communication with a dual RESS packs (128a, 128b) of different chemistry with different working voltages. Said each of the RESS (128a, 128b) pack is provided with a battery management system (129a, 129b). Said each of the RESS pack (128a, 28b) is connected to the said inverter system (124) by means of a plurality of electronic switch (131a, 131b). A plurality of CAN communication systems (132a, 132b) is provided connecting the said each of the battery management system (129a,129b) in the RESS packs (128a,128b) with the vehicle controller (123); and an electronic control unit (133), connecting the said vehicle controller unit (123) and said each of the electronic switch (131a, 131b). Said each of the electronic switch (131a, 131b) is placed in series to the positive terminal of the each RESS battery pack (128a,128b) and the other terminal of each of the electronic switch (131a, 131b) is connected to the positive terminal of the said inverter system (124). Negative terminals of all RESS battery packs (128a,128b) are connected to the negative terminal of the inverter system (124), each RESS battery pack (128a,128b) is provided with a battery management system (BMS) (129a, 129b) and a centralized battery system controller communicating with every BMS (129a,129b) of all RESSs (128a, 128b). Lithium-ion based battery packs are selected as RESS battery packs, more preferably for RESS packs of two different chemistries Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium ferrous phosphate (LFP) are selected. RESS battery pack with specific chemistry is operated based on factors such as power demand, SOC/SOH parameters of RESSs, mode of operation by battery i.e. discharge mode or charge mode, regenerative braking etc. Based on battery parameters such as SOC, SOH, temperature of each of the battery as well as power requirement from battery system, centralized battery system controller identifies the RESS pack (128a, 128b) most appropriate to be used at a given instant and turns on the electronic switch (131a, 131b) in series to appropriate RESS. The electronic vehicle controller unit (123) turns on the appropriate electronic switch (131a, 131b) to connect specific RESS pack (128a, 128b) to the electrical bus of the vehicle based on parameters and/or status of each RESS pack and also based on the instantaneous power requirement from battery system to achieve optimal performance from the energy storage system. Depending of vehicle system requirement, a particular RESS pack will be selected at an instant to be connected to the electrical bus of vehicle based on various factors. When the required energy capacity of vehicle battery system will be realized using two RESS packs (128a, 128b) involving different chemistries say ‘NMC’ and ‘LFP’. During peak power requirement say of about 100%, RESS battery pack (128a) with one chemistry say NMC could be considered for around 30% of total energy capacity and the rest 70% with RESS battery pack of another chemistry (128b) in particular LFP. Sizing of different RESS battery packs for energy rating is arrived based on the detailed vehicle system level simulations. Further based on environmental factors and battery parameters, it is possible to ensure safety of RESS battery packs following the conventional practices. Logics to operate a battery system can be developed for providing high power from RESS battery pack of one chemistry and continuous power from RESS battery pack of another chemistry, balanced and long life by appropriate strategy of selection of RESS based on SOC / SOH / power level and best range. Implementation of the said logics could be realized with a dedicated inverter system (124) controller which communicates with individual BMS (129a, 129b) of each of the RESS battery pack (128a, 128b) as well as vehicle controller (123) or alternatively, the logics could be implemented as a part of one of the BMS units corresponding RESSs which would also communicate with vehicle controller and other BMS units.
EXAMPLE 2
The present invention focusses on relieving the limitation of using RESS with single chemistry thereby providing a more optimal solution in terms of battery performance, battery life etc. The present invention provides a battery system (140) for electric vehicle, which uses three RESS battery packs of different chemistries with different working voltages, to overcome the vehicle range anxiety without compromising the battery life, comprising of: a vehicle transmission system (121) which is in direct communication with an electric motor (122). The said electric motor (122) is connected to the vehicle controller unit (123) at its one end. Said vehicle controller unit (123) at its one end is in direct communication with the brake (126) and accelerator (127) system of the vehicle and at its other end is in direct communication with a inverter system (124). The inverter system (124) is in direct communication with three RESS packs (135a, 135b, 135c) of different chemistry with different working voltages. Said each of the three RESS pack (135a, 135b, 135c) is provided with a battery management system (136a, 136b, 136c). Said each of the three RESS (135a, 135b, 135c) pack is connected to the said inverter system (124) by means of a plurality of electronic switches (131a, 131b). Three CAN communication systems (132a, 132b, 132c) is provided connecting the said each of the battery management system (136a, 136b, 136c) in the three RESS pack (135a, 135b, 135c) with the vehicle controller (123); and an electronic control unit (133), connecting the said vehicle controller unit (123) and said each of the electronic switch (131a, 131b). Said each of the electronic switch (131a, 131b) is placed in series to the positive terminal of the each RESS battery pack (135a, 135b) and the other terminal of each of the electronic switch (131a, 131b) is connected to the positive terminal of the said inverter system (124). Negative terminals of the RESS battery packs (135a, 135b) are connected to the negative terminal of the inverter system (124), each of the three RESS battery pack is provided with a battery management system (BMS) (136a, 136b, 136c) and a centralized battery system controller communicating with every BMS (136a, 136b, 136c) of all RESSs (135a, 135b, 135c). Lithium-ion based battery packs are selected as RESS battery packs, more preferably for RESS packs of three different chemistries Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium ferrous phosphate (LFP) and lithium-titanate-oxide (LTO) are selected. RESS battery pack with specific chemistry is operated based on factors such as power demand, SOC/SOH parameters of RESSs, mode of operation by battery i.e. discharge mode or charge mode, regenerative braking etc. Based on battery parameters such as SOC, SOH, temperature of each of the battery as well as power requirement from battery system, centralized battery system controller identifies the RESS pack most appropriate to be used at a given instant and turns on the electronic switch in series to appropriate RESS. The electronic vehicle controller unit turns on the appropriate electronic switch to connect specific RESS pack to the electrical bus of the vehicle based on parameters and/or status of each RESS pack and also based on the instantaneous power requirement from battery system to achieve optimal performance from the energy storage system. Depending of vehicle system requirement, a particular RESS pack will be selected at an instant to be connected to the electrical bus of vehicle based on various factors. when the required energy capacity of vehicle battery system will be realized using three RESS packs involving different chemistries say ‘NMC’, ‘LFP’ and ‘LTO’, maximum continuous power would be taken care for by a RESS with a specific chemistry say NMC (135a), peak power requirement for short duration would be addressed by another chemistry LTO (135b) meant for power application where the continuous C-rates are generally like 4C or 6C with peak C-rates up to 10C to 15C, which would also require good thermal dissipation for optimal performance and life requirement would be addressed by RESS with relevant chemistry, such as LFP (135c). Such a combination would facilitate achieving maximum power using RESS pack of one chemistry whenever required and rest of the time, RESS with another chemistry could be used. Thus the limitation of maximum power and life expectancy for the complete battery system could be resolved considering the combination of two or more RESSs packs with different chemistries. By such balancing based on RESS packs of different chemistries, the space constraint could be avoided. Also by such division RESS battery packs fitment would be ideal.
Sizing of different RESS battery packs (135a, 135b, 135c) for energy rating is arrived based on the detailed vehicle system level simulations. Further based on environmental factors and battery parameters, it is possible to ensure safety of RESS battery packs following the conventional practices. Logics to operate the electronic control unit (133) can be developed for providing high power from RESS battery pack of one chemistry and Continuous power from RESS battery pack of another chemistry, balanced and long life by appropriate strategy of selection of RESS based on SOC / SOH / power level and best range. Implementation of the said logics could be realized with a dedicated battery system controller which communicates with individual BMS (136a, 136b, 136c) of each of the RESS battery pack (135a, 135b, 135c) as well as vehicle controller (123) or alternatively, the logics could be implemented as a part of one of the BMS units corresponding RESSs which would also communicate with vehicle controller and other BMS units.
Although the proposed concept has been described as a way of example with reference to various models, it is not limited to the disclosed embodiment and that alternative designs could be constructed without deviating from the scope of invention as defined above.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the scope of the invention may be made by a person skilled in the art.