Systems and methods for power management using adaptive power split ratio

Methods and systems of power management in a hybrid vehicle are disclosed. A control system of the hybrid vehicle obtains battery temperature and catalyst temperature. The control system determines (a) whether the battery temperature is within an optimal battery temperature range and (b) whether the catalyst temperature is within an optimal catalyst temperature range. The control system determines a power split ratio (PSR) based on the determination of (a) and (b). The control system controls the engine and the motor-generator based on the determined PSR.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to vehicles, especially to power management of hybrid vehicles having an electrical motor and a fuel-powered engine.

BACKGROUND OF THE DISCLOSURE

A hybrid power generation system may include a hybrid control system, a battery, a motor-generator, and an engine (e.g., a diesel engine). A control system of the hybrid vehicle may direct the battery and/or the engine/motor-generator to provide power to move the vehicle. Additionally, in some instances, the engine/motor-generator may also provide power to recharge the battery. For instance, currently, when a state of charge (SOC) for the battery is below a minimum charging threshold, the control system may direct the engine/motor-generator to recharge the battery up to a charging threshold. As such, power management strategies of the hybrid vehicle may incorporate using the motor-generator and the engine effectively for more options than when only one or the other is implemented.

However, existing power management strategies focus on meeting emission and fuel economy targets without considering the states of the individual components. For example, to reduce the emission, the motor-generator may be used more frequently than the engine, but the battery's performance is derated when the operating temperatures are above the pre-set thresholds. Also, over time, the battery may degrade. For example, initially, a battery may last eight hours under normal usage. But, over time and due to the battery's degradation, the battery might last only four hours. Additionally, and/or alternatively, severe conditions, such as weather-related conditions and/or natural disasters, may cause more usage of a battery than normal. Furthermore, the life of the aftertreatment catalyst may be affected adversely due to constant operation at very high temperatures. As such, it may be desirable to develop a hybrid control system that can effectively use the hybrid components (both the engine and the motor-generator) to eliminate or alleviate one or more operational disadvantages described above.

SUMMARY

Various embodiments of the present disclosure relate to methods of power management in a hybrid vehicle. The hybrid vehicle may include an engine, a motor-generator, an aftertreatment system operatively coupled to the engine, a battery operatively coupled to the motor-generator, and a control system. The method includes obtaining, by the control system, battery temperature and catalyst temperature. The control system determines (a) whether the battery temperature is within an optimal battery temperature range and (b) whether the catalyst temperature is within an optimal catalyst temperature range. The control system determines a power split ratio (PSR) based on the determination of (a) and (b). The control system controls the engine and the motor-generator based on the determined PSR.

In some examples, the control system decreases the PSR when the catalyst temperature is lower than the optimal catalyst temperature range. In some examples, the PSR decrease is based on a rate at which the battery temperature or the catalyst temperatures changes and/or a rate at which the state of charge of the temperature changes.

In some examples, the control system decreases the PSR when the catalyst temperature is within or lower than the optimal catalyst temperature range and the battery temperature is higher than the optimal battery temperature range. In some examples, the control system increases the PSR when the battery temperature is lower than the optimal battery temperature range and the catalyst temperature is within or higher than the optimal catalyst temperature range. In some examples, the control system increases the PSR when the catalyst temperature is higher than the optimal catalyst temperature range and the battery temperature is within or lower than the optimal battery temperature range.

In some examples, the control system obtains geofencing data and determines whether the vehicle is in or approaching a lower-emission zone based on the geofencing data. Then, the control system sets the PSR at 1 when the vehicle is in or approaching the lower-emission zone. In some examples, the control system obtains lookahead data and determines the PSR based on the lookahead data. The lookahead data may include current or forward route condition. In some examples, the control system maintains the PSR when the catalyst temperature and the battery temperature are both within or higher than the respective optimal temperature ranges.

Also disclosed herein are hybrid vehicle systems with an engine, a motor-generator, an aftertreatment system operatively coupled to the engine, a battery operatively coupled to the motor-generator, and a control system which obtains battery temperature and catalyst temperature, determines (a) whether the battery temperature is within an optimal battery temperature range and (b) whether the catalyst temperature is within an optimal catalyst temperature range, determines a power split ratio (PSR) based on the determination of (a) and (b), and controls the engine and the motor-generator based on the determined PSR.

In some examples, the control system is further configured to decrease the PSR when the catalyst temperature is lower than the optimal catalyst temperature range. In some examples, the control system is further configured to decrease the PSR based on a rate at which the battery temperature or the catalyst temperatures changes. In some examples, the control system is further configured to decrease the PSR when the catalyst temperature is within or lower than the optimal catalyst temperature range and the battery temperature is higher than the optimal battery temperature range. In some examples, the control system is further configured to increase the PSR when the battery temperature is lower than the optimal battery temperature range and the catalyst temperature is within or higher than the optimal catalyst temperature range. In some examples, the control system is further configured to increase the PSR when the catalyst temperature is higher than the optimal catalyst temperature range and the battery temperature is within or lower than the optimal battery temperature range.

In some examples, the hybrid vehicle system further includes a telematics unit such that the control system obtains geofencing data from the telematics unit, determines whether the vehicle is in or approaching a lower-emission zone based on the geofencing data and sets the PSR at 1 when the vehicle is in or approaching the lower-emission zone. In some examples, the control system obtains lookahead data from the telematics unit and determines the PSR based on the lookahead data. The lookahead data may include current and/or forward route condition.

Also disclosed herein are control systems of a hybrid vehicle that includes an engine, a motor-generator, a battery operatively coupled to the motor-generator, and a control system. The control system is operable to obtain battery temperature and catalyst temperature, determine whether the battery temperature is within a predetermined optimal battery temperature range, determine whether the catalyst temperature is within a predetermined optimal catalyst temperature range, determine a power split ratio (PSR) based on the determination of the battery temperature, catalyst temperature, the rate of change of these temperatures, and a rate of change of state of charge (SOC) of the battery, and control the engine and the motor-generator based on the determined PSR.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the disclosure and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner. While the present disclosure is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the present disclosure to the particular embodiments described. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the present disclosure is practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure, and it is to be understood that other embodiments can be utilized and that structural changes can be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents.

Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more embodiments. Furthermore, the described features, structures, or characteristics of the subject matter described herein may be combined in any suitable manner in one or more embodiments.

For the purposes of promoting an understanding of the principles of the present disclosure, reference is now made to the embodiments illustrated in the drawings, which are described below. The exemplary embodiments disclosed herein are not intended to be exhaustive or to limit the disclosure to the precise form disclosed in the following detailed description. Rather, these exemplary embodiments were chosen and described so that others skilled in the art may utilize their teachings.

The terms “couples,” “coupled,” and variations thereof are used to include both arrangements wherein two or more components are in direct physical contact and arrangements wherein the two or more components are not in direct contact with each other (e.g., the components are “coupled” via at least a third component), but yet still cooperate or interact with each other. Furthermore, the terms “couples,” “coupled,” and variations thereof refer to any connection for machine parts known in the art, including, but not limited to, connections with bolts, screws, threads, magnets, electro-magnets, adhesives, friction grips, welds, snaps, clips, etc.

Throughout the present disclosure and in the claims, numeric terminology, such as first and second, is used in reference to various components or features. Such use is not intended to denote an ordering of the components or features. Rather, numeric terminology is used to assist the reader in identifying the component or features being referenced and should not be narrowly interpreted as providing a specific order of components or features.

FIG.1shows a vehicle system100that includes an engine power source101, which may be an internal combustion engine for example, and a motor-generator106power source in parallel hybrid vehicles. The vehicle100may be configured as any type of hybrid-powered vehicle (e.g., a series hybrid electric vehicle, a strong parallel hybrid electric vehicle, a mild parallel hybrid electric vehicle, etc.). As such, the vehicle100may be configured as a plugin or non-plugin and an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up truck), tanks, airplanes, off-highway equipment such as mining equipment, etc. The various components of the vehicle100may be described as follows. The vehicle100is shown to generally include a powertrain system110, an exhaust aftertreatment system108, and a control system109, where the control system109is communicably coupled to each of the engine101, the exhaust aftertreatment system108operatively coupled with the engine101, the motor-generator106, and a battery107operative coupled with the motor-generator106. An inverter is omitted from the figure for simplicity, but it is understood that an inverter can be placed between the motor-generator106and the battery107to convert between alternating current (AC) and direct current (DC). In some examples, the vehicle100may also include telematics systems to facilitate exchange of information or data in an intelligent transportation system (ITS).

The powertrain system110facilitates power transfer from the engine101and/or motor-generator106to power and/or propel the vehicle100. The powertrain system110includes an engine101and a motor-generator106operably coupled to a transmission102that is operatively coupled to a drive shaft103, which is operatively coupled to a differential104, where the differential104transfers power output from the engine101and/or motor-generator106to the final drive (shown as wheels105) to propel the vehicle100. In this regard, the powertrain system110is structured as an electrified powertrain. The electrified powertrain includes the motor-generator106, where the motor-generator106may include a torque assist feature, a regenerative braking energy capture ability, a power generation ability, and any other feature of motor-generators used in hybrid vehicles. In this regard, the motor-generator106may be any conventional motor-generator that is capable of generating electricity and producing a power output to drive the transmission102. The motor-generator106includes a power conditioning device such as an inverter and motor control system. The electrified powertrain may also include any one or more of several electrified accessories including, but not limited to, an electrically driven/controlled air compressor, an electrically driven/controlled engine cooling fan, an electrically driven/controlled heating venting and air conditioning system, an alternator, etc., where the controllability may stem from the control system109. It should be understood that the present disclosure contemplates any and all other types of electrically and mechanically powered accessories that may be a part of the powertrain system110and/or separate from the powertrain system110but included in the vehicle100.

As a brief overview, the engine101receives a chemical energy input (e.g., a fuel such as gasoline or diesel) and combusts the fuel to generate mechanical energy, in the form of a rotating crankshaft. In comparison, the motor-generator106may be in a power receiving relationship with an energy source, such as battery107that provides an input energy (and stores generated electrical energy) to the motor-generator106for the motor-generator106to output in form of useable work or energy to in some instances propel the vehicle100alone or in combination with the engine101. In this configuration, the hybrid vehicle100has a parallel drive configuration. However, it should be understood, that other configurations of the vehicle100are intended to fall within the spirit and scope of the present disclosure (e.g., a series configuration and non-hybrid applications, such as a full electric vehicle, etc.). As a result of the power output from at least one of the engine101and the motor-generator106, the transmission102may manipulate the speed of the rotating input shaft (e.g., the crankshaft) to effect a desired drive shaft103speed. The rotating drive shaft103is received by a differential104, which provides the rotation energy of the drive shaft103to the final drive105. The final drive105then propels or moves the vehicle100.

The engine101may be structured as any internal combustion engine (e.g., compression-ignition or spark-ignition), such that it can be powered by any fuel type (e.g., diesel, ethanol, gasoline, etc.). Similarly, although termed a “motor-generator”106throughout the pages of the disclosure, thus implying its ability to operate as both a motor and a generator, it is contemplated that the motor-generator component, in some embodiments, may be an electric generator separate from the electric motor of the hybrid vehicle100. Furthermore, the transmission102may be structured as any type of transmission, such as a continuous variable transmission, a manual transmission, an automatic transmission, an automatic-manual transmission, a dual clutch transmission, etc. Accordingly, as transmissions vary from geared to continuous configurations (e.g., continuous variable transmission), the transmission can include a variety of settings (gears, for a geared transmission) that affect different output speeds based on the engine speed. Like the engine101and the transmission102, the drive shaft103, differential104, and final drive105may be structured in any configuration dependent on the application (e.g., the final drive105is structured as wheels in an automotive application and a propeller in an airplane application). Further, the drive shaft103may be structured as a one-piece, two-piece, and a slip-in-tube driveshaft based on the application.

Moreover, the battery107may be configured as any type of rechargeable (i.e., primary) battery and of any size. That is to say, the battery107may be structured as any type of electrical energy storing and providing device, such as one or more capacitors (e.g., ultra-capacitors, etc.) and/or one or more batteries typically used or that may be used in hybrid vehicles (e.g., Lithium-ion batteries, Nickel-Metal Hydride batteries, Lead-acid batteries, etc.). The battery107may be operatively and communicably coupled to the control system109to provide data indicative of one or more operating conditions or traits of the battery107. The data may include a temperature of the battery, a current into or out of the battery, a number of charge-discharge cycles, a battery voltage, etc. As such, the battery107may include one or more sensors coupled to the battery107that acquire such data. In this regard, the sensors may include, but are not limited to, voltage sensors, current sensors, temperature sensors, etc. In some examples, the sensors are part of a battery management system (BMS) which is operable with the control system109of the vehicle to monitor the state of the battery107as needed. In some examples, the BMS is implemented in the control system109as a battery monitoring module that receives and processes data from the sensors.

As also shown, the vehicle100includes an exhaust aftertreatment system108in fluid communication with the engine101. The exhaust aftertreatment system108receives the exhaust from the combustion process in the engine101and reduces the emissions from the engine101to less environmentally harmful emissions (e.g., reduce the NOx amount, reduce the emitted particulate matter amount, etc.). The exhaust aftertreatment system108may include any component used to reduce diesel exhaust emissions, such as a selective catalytic reduction catalyst, a diesel oxidation catalyst, a diesel particulate filter, a diesel exhaust fluid doser with a supply of diesel exhaust fluid, and a plurality of sensors for monitoring the system108(e.g., a NOx sensor). It should be understood that other embodiments may exclude an exhaust aftertreatment system and/or include different, fewer, and/or additional components than that listed above. All such variations are intended to fall within the spirit and scope of the present disclosure.

The vehicle100is also shown to include a telematics unit111. The telematics unit111may be structured as any type of telematics control unit. Accordingly, the telematics unit111may include, but is not limited to, a location positioning system (e.g., global positioning system) to track the location of the vehicle (e.g., latitude and longitude data, elevation data, etc.), one or more memory devices for storing the tracked data, one or more electronic processing units for processing the tracked data, and a communications interface for facilitating the exchange of data between the telematics unit111and one or more remote devices (e.g., a provider/manufacturer of the telematics device, etc.). In this regard, the communications interface may be configured as any type of mobile communications interface or protocol including, but not limited to, Wi-Fi, WiMax, Internet, Radio, Bluetooth, Zigbee, satellite, radio, Cellular, GSM, GPRS, LTE, and the like. The telematics unit111may also include a communications interface for communicating with the control system109of the vehicle100. The communication interface for communicating with the control system109may include any type and number of wired and wireless protocols (e.g., any standard under IEEE 802, etc.). For example, a wired connection may include a serial cable, a fiber optic cable, an SAE J1939 bus, a CAT5 cable, or any other form of wired connection. In comparison, a wireless connection may include the Internet, Wi-Fi, Bluetooth, Zigbee, cellular, radio, etc. In one embodiment, a control system area network (CAN) bus including any number of wired and wireless connections provides the exchange of signals, information, and/or data between the control system109and the telematics unit111. In other embodiments, a local area network (LAN), a wide area network (WAN), or an external computer (for example, through the Internet using an Internet Service Provider) may provide, facilitate, and support communication between the telematics unit111and the control system109. In still another embodiment, the communication between the telematics unit111and the control system109is via the unified diagnostic services (UDS) protocol. All such variations are intended to fall within the spirit and scope of the present disclosure.

An operator input/output device112enables an operator of the vehicle to communicate with the vehicle100and the control system109. For example, the operator input/output device112may include, but is not limited, an interactive display (e.g., a touchscreen, etc.), an accelerator pedal, a clutch pedal, a shifter for the transmission, a cruise control input setting, etc. Via the input/output device112, the operator can designate preferred characteristics of one or more vehicle parameters. In some examples, the touchscreen may be part of a computing device or processing device that receives certain information from the operator, such as the destination of the vehicle100, the expected mileage for a predetermined period of time, and/or the minimal distance to be traveled. A thermometer113that is operatively coupled with the battery107and the control system109allows for the control system109to receive data of how hot or cold the battery107is getting during the operation of the vehicle100. Furthermore, the engine101and the motor-generator106define a genset114which is capable of charging the battery107by activating the engine101whose mechanical power is converted into electrical power via the motor-generator106and transferred to the battery107.

FIG.2shows the function and structure of the control system109, are shown according to one example embodiment. The control system109is shown to include a processing circuit200including a processor201and a memory202. The processor201may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital signal processor (DSP), a group of processing components, or other suitable electronic processing components. The one or more memory devices202(e.g., NVRAM, RAM, ROM, Flash Memory, hard disk storage, etc.) may store data and/or computer code for facilitating the various processes described herein. Thus, the one or more memory devices202may be communicably connected to the control system109and provide computer code, or data, or instructions to the control system109for executing the processes described in regard to the control system109herein. Moreover, the one or more memory devices202may be or include tangible, non-transient volatile memory or nonvolatile memory. Accordingly, the one or more memory devices202may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

The memory202is shown to include various modules for completing the activities described herein. More particularly, the memory202includes an internal information module203, a power split ratio (PSR) strategy module204, and a control module205. The internal information module203is a data-collection module that receives raw data from each of the components. The raw data may include one or more of the following: battery status data206such as the SOC of the battery107, catalyst and/or emission data207such as catalyst temperature and onboard emission estimation as received from the exhaust aftertreatment system108, GPS, geofencing, and/or lookahead data208as received from the telematics unit111, operator's power demand and/or destination data209as received from the operator input/output device112, and battery temperature data210as received from the thermometer113. The lookahead data208may include current or forward route condition, for example.

Upon receiving the raw data using the internal information module203, the PSR strategy module204calculates a target power level for the genset114and the battery107, taking into consideration factors such as trip distance, battery SOC, catalyst and battery temperatures, onboard emission level, and GPS location, for example. In some examples, the raw data may be used in distance-to-destination calculation, vehicle route calculation, traffic estimation, etc. The control module205then uses the target power level calculated by the PSR strategy module204to send an engine control signal211to the engine101and a battery control signal212to the battery107. For example, the engine control signal211may indicate whether to activate the engine101to use the genset114in providing electrical power to the battery107, and the battery control signal212may control the battery to provide electrical power to the motor-generator106to move the vehicle100instead of the engine101.

As examples, the trip distance is used to define a SOC target level300to achieve a blended mode operation302as shown inFIG.3, which compares the SOC target level300of the blended mode, shown in a dotted line, with an actual SOC profile of the blended mode302in a driver cycle, shown in a solid line. The battery SOC feedback is used to increase or decrease battery usage to bring the SOC closer to the target level. The catalyst and battery temperatures are used to control engine and battery usage by updating PSR accordingly. For example, when the battery temperature is high, battery power is lowered and engine power is increased so that the battery is allowed to cool down to prevent derating. The onboard emission estimation can be used to optimize engine usage. For example, thermal management strategies can be employed when the estimated emissions exceed predefined thresholds. The geofencing zone information can indicate which areas require that the battery alone is used.

While various modules with particular functionality are shown inFIG.2, it should be understood that the control system109and memory202may include any number of modules for completing the functions described herein. For example, the activities of multiple modules may be combined as a single module, as additional modules with additional functionality may be included, etc. Further, it should be understood that the control system109may further control other vehicle activity beyond the scope of the present disclosure.

FIG.4shows an example of a method400performed by the PSR strategy module204according to some embodiments. A PSR is defined as the ratio of the power to be provided by the motor-generator106to the total power demanded by the operator. Therefore, if only the motor-generator106is to provide power, the PSR would be 1, and if only the engine101is to meet all the power demand, the PSR would be 0. The PSR can be written as a function of various input data, such as:
PSR=f(DDP,SOC,Tbatt,TAT,Dist,EVreq,Emission)
where DDP is the driver demand power at wheels, SOC is the current state-of-charge of the battery, Tbattis the temperature of the battery, TATis the temperature of the aftertreatment system, Dist is the distance to be traveled, EVreqis the all-electric vehicle requirement in which certain zones may require the vehicle to operate in all-electric mode without activating the engine, and Emission is the estimated emission level of the vehicle.

In the method400, an initial PSR is derived in view of optimizing fuel economy of the vehicle100using any method that are known and existing in the industry; step401. The PSR strategy module204then determines whether this initial PSR is to be changed, and if so, by how much, using the following steps. In some examples, the GPS location is obtained; step402. The GPS location may indicate whether the vehicle100is in a geofenced location or any other areas with a certain emission level limit requirement, such as low-emission or zero-emission zones; step403. For example, zero-emission zones only allow all-electric vehicles, in which case the PSR must be set to 1. Upon determining that the vehicle100is in the low-emission zone as indicated by the geofencing of the area, the algorithm may set the PSR to 1; step404. Additionally, the GPS location can be used to calculate the distance to destination and update the PSR in-order to reach the desired target SOC.

Otherwise, when there is no geofencing, the PSR strategy module204proceeds to obtain the battery temperature; step405. The battery temperature (e.g., battery temperature data210) is obtained from the thermometer113coupled with the battery107as previously explained. The PSR strategy module204decides whether the battery temperature is within a predetermined optimal temperature range; step406. If so, the catalyst temperature is obtained, per step407. Note that the catalyst temperature is included in the catalyst and/or emission data207provided by the exhaust aftertreatment system108in some examples, as previously explained. Subsequently, the PSR strategy module204decides if the catalyst temperature is within the predetermined optimal range, per step410. If the catalyst temperature is also within optimal range, the PSR is kept unchanged, in step413. If the catalyst temperature is lower than the optimal range, the PSR is reduced to enable the exhaust aftertreatment system108to warm up, per step415. If the catalyst temperature is higher, the PSR is increased to allow the catalyst temperature to cool down, in step414. The PSR is modulated based on the rates at which the battery and catalyst temperatures change to ensure the temperatures of battery and catalyst would not reach thermal limits and frequency of performance derates is reduced.

If in step406, the battery temperature is determined to be higher than the optimal range, the catalyst temperature is determined, in step408. The catalyst temperature is checked to determine if the catalyst temperature is within the predetermined optimal range, in step411. If the catalyst temperature is determined to be within or lower than optimal range, then the PSR is reduced to allow the battery temperature to cool down, as shown in step415. If at step411, the catalyst temperature is determined to be higher than the optimal range, then the PSR is maintained, as shown in step416.

If in step406, the battery temperature is determined to be lower than the optimal temperature threshold, the catalyst temperature is determined, in step409. The catalyst temperature is checked to determine if the catalyst temperature is within the predetermined optimal range, in step412. If the catalyst temperature is determined to be lower than the optimal range, then the PSR is reduced to warm up the exhaust aftertreatment system108, per step417. At this step, the warming up of the exhaust aftertreatment system is given priority over warming up of the battery, since the temperature of the exhaust aftertreatment system can directly affect the tail-pipe emissions. If the catalyst temperature is determined to be within the optimal range or higher than the optimal range, the PSR is increased to warm up the battery107, prioritizing the warming up of the battery over cooling down of the catalyst, per step418. Along with the optimal range, the rate of change of SOC and the rate of change of temperature are also used to calculate the PSR and/or the changes in the PSR.

Table 1 below summarizes the decisions regarding PSR in determining different values for the battery temperature and the catalyst temperature, based on the flow chart ofFIG.4. The increment value of PSR is calibrated based on the powertrain architecture and component sizes (battery size, types of aftertreatment being used, etc.). In some examples, the increment value at which the PSR changes may be greater for series hybrid architecture than parallel hybrid architecture.

FIG.5shows an alternative partial design of a vehicle500that implements the PSR strategy module204as disclosed herein according to some embodiments. Some components fromFIG.1such as the exhaust aftertreatment system108, the control system109, the operator input/output device112, and the telematics unit111are omitted from this figure for simplicity, but it is understood that any additional components may be included as suitable for the purpose. The vehicle500includes two inverters501and502as well as two motor-generators106and503. When the engine101is activated to provide mechanical energy for the motor-generator106, the AC power generated by the motor-generator106is converted to DC power by the first inverter501. The DC power can either be used to charge the battery107or be converted back to AC power through the second inverter502. The second inverter502can then power the second motor-generator503to provide mechanical energy to operate the transmission102, thereby moving the vehicle500. The battery107can also provide DC power to the inverter502if the battery107has a sufficiently high SOC, in which case the engine101can be deactivated to reduce emission.

Controlling the PSR value based not only on meeting emission and fuel economy targets but also considering the states of the individual components in the hybrid vehicle system allows for emphasis to be placed on the life and state-of-health of the components such as the battery, motor-generator, engine, aftertreatment system, etc., without derating system performance. For example, an electrical power (P) to be supplied is calculated as shown below, where DDP is the driver demand power at the wheels, ηTMis the efficiency of the transmission102, and ηEMis the efficiency of the electric motor of the motor-generator503:

The electrical power provided by the battery107(Pbatt) is calculated as follows: Pbatt=PSR*P, and the electrical power provided by the genset114(Pgenset) is calculated as follows: Pgenset=(1−PSR)*P. The Pbattvalue can be affected by the SOC and the temperature of the battery107. The Pgensetvalue can be affected by the emission level and the aftertreatment temperature.

There is a plurality of different power split management strategies that impact the sizing of energy sources (engine and battery). For example, a “baseline” strategy as known in the art may use the charge-depleting (uses the battery for power) mode until the battery reaches a predetermined SOC and then use the charge-sustaining (use the genset for power) mode to maintain the battery SOC. A “blended mode” strategy uses both power sources in various ways. One type of such blended mode strategy involves dynamically adjusting the SOC target such that depletion of the battery is better controlled. The blended mode strategy which involves changing the PSR value as explained above is compared against baseline strategy.

Table 2 below compares the two aforementioned strategies.FIGS.3and6show the difference between trajectories of the SOC curve when each strategy is applied. For example, the SOC curve of the blended mode (302inFIG.3) shows a steady decrease in the SOC from 90% to 20% during the 10 hours in which the vehicle is in operation, whereas the SOC curve of the charge-depleting-and-charge-sustaining mode (a.k.a. “baseline method” as represented by a charge depleting mode600and a charge sustaining mode602inFIG.6) shows a steep decrease from 90% to 20% SOC in the first 4 hours in the charge depleting mode600during which the battery107is in operation, thereby depleting the SOC of the battery107. Thereafter, the baseline method maintains 20% SOC in the battery107for the remainder of the 10-hour operation in the charge sustaining mode602by using the engine101to provide the power to drive the vehicle100instead of the battery107. The baseline method600,602is known in the art. When the SOC curves in the two different modes are compared, it is observed that the baseline method (600and602) ofFIG.6shows the measured SOC curve in the charge depleting mode600decreasing at a much faster rate than the blended mode method302inFIG.3because the baseline method600,602relies on depleting the battery until a certain threshold, after which the engine takes over to provide the power.

Table 2 above shows the resulting improvements in fuel economy, battery life, and emission after each of the blended mode302is implemented, when compared with the baseline method600,602. The blended mode method302improves not only the fuel economy but also the battery life and emissions. As such, the blended mode method302has the better overall system level performance when compared with the baseline method600,602. The aforementioned Table 2 andFIGS.3and6were obtained in simulation, using an electronic model (for example, a virtual computer model) of a class 5 vehicle weighing 19,500 lb. (approximately 8850 kg) and having a 2.8-liter natural gas engine, a range extender architecture with e-axle, and two compact batteries (39.5 kWh and 34.6 kWh).

Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. The scope is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.”

Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B or C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C.