CN113370963A

CN113370963A - System and method for implementing dynamic operating modes and control strategies for hybrid vehicles

Info

Publication number: CN113370963A
Application number: CN202110539715.4A
Authority: CN
Inventors: 安德鲁·弗兰克; 林湛乔; 克利希纳·库马尔; 安东尼·塞拉
Original assignee: Cummins Electrified Power NA Inc
Current assignee: Cummins Electrified Power NA Inc
Priority date: 2013-02-08
Filing date: 2014-02-07
Publication date: 2021-09-10
Also published as: CN108313049B; CN103978974B; CN204136757U; CN108313049A; CN103978974A; CN103978880A; CN204236461U; CN103978880B

Abstract

Systems and methods for implementing dynamic operating modes and control strategies for hybrid vehicles are disclosed. Disclosed in one embodiment is a method comprising: determining a state of charge (SOC) of the battery; determining a speed of the vehicle; selecting a charge-depleting operating mode of the vehicle if the SOC is greater than a specified first threshold; selecting a charge-sustaining mode of operation of the vehicle if the SOC is less than a specified second threshold during operation of the vehicle. In another embodiment, a system is disclosed having a controller that operates a powertrain system according to various embodiments.

Description

System and method for implementing dynamic operating modes and control strategies for hybrid vehicles

The present application is a divisional application of an invention patent application having an application date of 2014, 7, national application number of 201810142940.2 entitled "system and method for implementing a dynamic operating mode and a control strategy for a hybrid vehicle". And the invention patent application having an application date of 2014, 2/7, an application number of 201810142940.2 and an invention name of "system and method for implementing dynamic operation mode and control strategy for hybrid vehicle" is a divisional application of the invention patent application having a national application number of 201410044794.1 and an invention name of "system and method for implementing dynamic operation mode and control strategy for hybrid vehicle".

Technical Field

The present application relates to hybrid vehicles and, more particularly, to systems and methods for implementing dynamic operating modes and control strategies for hybrid vehicles.

Background

In the field of Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), there are many possible powertrain (or powertrain) configurations that are capable of implementing multiple operating modes. For example, within the HEV realm alone, HEV powertrain systems can be configured to implement series, parallel, series-parallel, and all-electric modes of operation. Additionally, some of these modes may be configured to operate according to different strategies such as power conservation, power consumption, and the like.

These different modes and strategies provide advantages such as range extension, fuel efficiency, operation of the Internal Combustion Engine (ICE) on its ideal operating curve (IOL), and full electric operation. It is desirable to have a single powertrain system that can implement the various control strategies and operating modes described above based on desired driving characteristic metrics, such as fuel efficiency, range extension, maximum range of electrical energy, efficient battery usage, etc., during the various driving conditions that may exist and under the various strategies that may be employed.

Disclosure of Invention

The following presents a simplified summary of the invention in order to provide a basic understanding of some applications described herein. This summary is not an extensive overview of the claimed subject matter. This summary is not intended to identify key or critical elements of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Its sole purpose is to present some concepts of the claimed subject matter in a simplified form as a prelude to the more detailed description that is presented later.

Systems and/or methods for controlling a dual-motor, dual-clutch powertrain system for HEVs and PHEVs are disclosed. Disclosed in one embodiment is a method comprising: determining a state of charge (SOC) of the battery; determining a speed of the vehicle; selecting a charge-depleting operating mode of the vehicle if the SOC is greater than a specified first threshold; selecting a charge-sustaining mode of operation of the vehicle if the SOC is less than a specified second threshold during operation of the vehicle. In another embodiment, a system is disclosed having a controller that operates the power system in accordance with various embodiments.

Other features and applications of the present system presented in the following detailed description can be understood in conjunction with the figures provided within this application.

Drawings

Exemplary embodiments are shown with reference to the drawings. It is to be understood that the embodiments and figures disclosed herein are to be considered illustrative and not restrictive.

FIG. 1 illustrates one possible embodiment of a hybrid or plug-in hybrid vehicle implemented according to the principles of the present application.

FIG. 2 illustrates one possible embodiment of a powertrain architecture in a HEV or PHEV vehicle implemented according to the principles of the present application.

Fig. 3A to 3C show a schematic flow of different modes of operation achieved by the powertrain architecture of fig. 2.

Fig. 4A shows a feasible set of operating envelope curves and efficiency islands (efficiency island) for a motor-generator in a powertrain system configured as shown in fig. 2.

FIG. 4B illustrates one possible embodiment of a control flow diagram using the information shown in FIG. 4A.

Fig. 5A and 5B illustrate two possible embodiments of mode control and/or operation for a HEV and/or PHEV vehicle, such as may be configured as shown in fig. 2.

FIG. 6 is one possible embodiment of a control flow diagram for a HEV and/or PHEV vehicle, such as may be configured as shown in FIG. 2.

Fig. 7 and 8 illustrate dynamic operation diagrams for switching various modes for HEV and/or PHEV vehicles implemented according to the principles of the present application.

FIG. 9 is one possible embodiment of a state diagram for a mode transition flow diagram.

Fig. 10-12 illustrate various embodiments of advanced control operations designed to improve battery performance and life.

Detailed Description

As used herein, the terms "component," "system," "interface," and the like are intended to refer to a computer-related entity, such as hardware, software (e.g., in execution), and/or firmware. For example, a component may be a process running on a processor, an object, an executable, and/or a computer. By way of illustration, both an application running on a server and the server can be a component. One or more components can reside within a process and a component can be localized on one computer and/or distributed between two or more computers.

The claimed subject matter is described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject invention. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the subject invention.

Introduction to the word

In one embodiment, a control algorithm is provided for managing dynamic operating modes and/or control strategies for a Hybrid Electric Vehicle (HEV), which may be applied to both plug-in HEVs and non-plug-in HEVs. Additionally, these control algorithms may allow for efficient, cost-effective, and responsive operation of the battery and motor. In other embodiments, it may also allow the Prime Mover (PM) to be minimized to achieve a high degree of power mixing. Suitable PMs may include: an ICE, a fuel cell, or any other combustion, chemical, and/or fuel-based (e.g., known liquid or gaseous fuel) prime mover.

By "high power hybrid" is meant that the vehicle (e.g., HEV, PHEV, etc.) and/or powertrain may be designed to use as much electrical energy stored within the battery as possible during the driving cycle to provide motive power for the vehicle. The electrical energy stored within the battery may be derived from a number of sources: regenerative braking, PM charging operation, or external charging from a wall outlet or otherwise. In other embodiments, electrical power (e.g., derived from on-board and off-board sources and by an electric motor or motors and/or batteries) may be managed by multiple controllers connected together in various ways to enable proper management of the batteries to improve range, life, and performance.

It is known that in many cases the life of a battery in an electric or hybrid vehicle may be less than 1/4 for its expected life. In certain embodiments, hybrid vehicles (HEVs, PHEVs, etc.) manage how the vehicle is used and/or driven to achieve a desired range and life with a particular set of batteries. Thus, in certain embodiments, it is desirable to coordinate the control of the engine, transmission, and battery pack with a software controller to achieve a desired fuel economy or fuel consumption and possibly also a desired electric range and battery life.

It should be appreciated that the control software for the vehicle may run on one controller (and this controller sends signals to various components of the powertrain), or alternatively the control software may be distributed to multiple controllers in any known manner, where a subset of the multiple controllers may communicate with a subset of the multiple controllers. Thus, any reference to the term "controller" may also encompass embodiments comprising a plurality of controllers and distributed control software.

One embodiment of a vehicle/powertrain system

FIG. 1 is a vehicle and/or powertrain capable platform (100) in a variety of vehicle and/or powertrain capable embodiments in which the techniques of the present invention may find application.

The vehicle 100 (shown in fig. 1) includes a dual clutch-dual motor HEV/PHEV powertrain that is capable of dynamically operating as an all-electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle at different times during a travel cycle through control operations. The engine (or any suitable PM)102 is disposed on a common drive shaft 112 carrying the two

motors

106 and 110. The clutch 104 is located between the engine 102 and the electric machine 106 and the clutch 108 is located between the electric machine 106 and the electric machine 110. As will be described in further detail below, the

clutches

104 and 108 may be actuated to achieve different operating modes of the vehicle 100.

The battery 114 uses the electrical charge to power the

motors

106 and 110. The battery 114 may draw power through on-board charging (e.g., using the engine 102 and the electric machine 106), regenerative braking (e.g., using the electric machine 110 alone or in combination with the electric machine 106), or through an optional wall charger 116. The wall charger 116 may draw power from a wall outlet and the charger 116 may be designed according to local standards for grid distribution.

The drive shaft 112 delivers and outputs mechanical power to and from a final drive (final drive)120, which the final drive 120 then delivers to

wheels

122A and 122B, which are rear wheels in this embodiment. Final drive 120 may include a differential optionally combined with additional gearing, such as from a manual transmission, an automatic transmission, a mechanical or electronic Continuously Variable Transmission (CVT), or a Power Split Device (PSD) as used in toyota pluris vehicles. Additionally, it should be appreciated that front wheel drive or all wheel drive embodiments are also possible embodiments and are within the scope of the present application. Other possible embodiments may include: (1) a front wheel driving structure of a front engine/double motors; (2) a structure of a front engine/single motor or double motor/variable transmission (e.g., CVT, automatic transmission, manual transmission, electronic transmission, planetary transmission, etc.); and (3) the structure of a front engine/single motor gearbox and a rear motor gearbox. Several such embodiments are disclosed in a commonly owned patent application having a patent application number of 13/762,860 entitled "POWERTRAIN architecture FOR dual MOTOR, dual CLUTCH HYBRID vehicle" (TWO-CLUTCH configuration FOR TWO-MOTOR, TWO-CLUTCH HYBRID ELECTRIC VEHICLES) "filed on even date herewith (and incorporated herein by reference).

In one embodiment, the motor 110 may have a higher torque and/or power rating than the motor 106. The rated power of the two motors can be adjusted according to the application of the vehicle; in one embodiment, however, the electric machine 106 may be 1/2 for the power and torque of the electric machine 110 and the PM may be approximately the power of the electric machine 106. In another embodiment, where the all-electric mode may have higher performance than in ICE operation, the ICE and the electric machine 106 may be much smaller than the electric machine 110. Such vehicles may be used in certain situations where limited charging facilities are to be used to provide electrical power for full electric operation and other possible situations.

In another embodiment, both

motors

106 and 110 may be downsized for reduced cost/weight. In such an embodiment, it may be desirable to operate both

motors

106 and 110 by closing the clutch 108 more frequently to make sufficient torque available and/or to achieve a desired level (e.g., a 30% level) when the vehicle is launched. Such motor dimensions may be specifically designed according to the size, weight and/or intended function of the intended vehicle (e.g., passenger vehicle, light truck, cargo vehicle, etc.). In certain embodiments, the motor 110 comprises a high torque motor and the motor 106 comprises a low torque motor.

FIG. 2 illustrates one embodiment of one possible control system 200 for a vehicle and/or powertrain, according to the principles and/or design of FIG. 1. The controller 202 may include a suitable combination of hardware, firmware, and/or software for inputting various system signals and outputting various control signals to achieve desired operation of the vehicle 100. Signals may be input into the controller 202 from sensors and/or actuators via a CAN bus architecture as is known in the art. Possible signal inputs to the controller 202 may include: vehicle speed, degree of drive shaft rotation, degree of crankshaft rotation, state of charge (SOC) of the battery, driver demand via actuation of the accelerator pedal and brake pedal, clutch slip, and other possible signals related to vehicle operation under various different possible conditions.

Other signals for the controller 202 may also include the following:

(1) external charger information, i.e., level 1, level 2, and other characteristics such as charging time, grid-to-vehicle, vehicle-to-grid, charging history, etc.

(2) Battery management system information such as state of charge (SOC), temperature of the battery pack and individual batteries, state of health (SOH), SOC and temperature history, instantaneous power capacity, fault codes, contactor status, battery voltage and current, etc.

(3) Engine controller data such as SOH, fuel usage, speed, throttle, temperature, torque, etc.

(4) Data of the clutch 1, such as on/off, clutch position, engine start/series operation, temperature, etc.

(5) Data of the motor 1(M1), such as motoring or generating, on/off, rotational speed, torque, temperature, voltage, current, and the like.

(6) Data for clutch 2, such as on/off, position, pressure, M1+ M2 electric, engine + M1+ M2 in parallel, engine + M1 operating in series with M2, temperature, etc.

(7) Motor drives with M2 include data such as on/off, speed, torque, temperature, voltage, current, single motor drive, dual motor drive, series operation, parallel operation temperature, etc.

Other system signals and/or control signals may be connected to the controller 202 through various interfaces and/or subsystem controllers, such as the engine controller 102a, the clutch actuators 104a and 108a, the motor controllers 106a and 110a, and the battery management system 114 a. It should be appreciated that the controller 202 may input other signals and send control signals from other sensors and/or actuators.

Working mode examples

A number of possible operating modes for HEV and PHEV vehicles are contemplated for a vehicle/powertrain similar to that of fig. 1 and 2, including:

(1) all Electric Mode (AEM): in this mode, energy may be provided by the battery without having to be concerned about where the energy comes from (e.g., on-board or off-board). Such a mode may implement a "charge-depleting" strategy whereby it may be desirable to provide as many "all-electric" miles as possible (e.g., according to some suitable metric or state) before initiating a PM. The AEM can be implemented by one motor or two motors operating (e.g., using energy from a battery pack).

(2) Prime mover mode 1(PMM 1): in this mode, the vehicle may be substantially powered by the PM and the battery's electrical energy may be used to boost performance. This mode may implement a "charge retention" strategy whereby electrical energy may be subsequently returned to the battery via the PM to provide a solid foundation for the SOC of the battery. This mode may also be used to achieve a temporary maximum speed when power of the PM is added to the motor. Sustained maximum speed can be achieved with PM only.

(3) Prime mover mode 2(PMM 2): in this mode, the electric machine 110 provides substantially all of the driving power (motive power) and the electric machine 106 provides electrical energy to drive the vehicle through the electric machine 110 and maintain the battery within a desired SOC range. This mode may also implement a "charge retention" strategy.

Fig. 3A-3C illustrate only the three modes enumerated above, although there are many possible intermediate modes that can be implemented on the vehicle 100. Fig. 3A shows the AEM mode. In this mode, electrical energy is delivered from the battery 114 to one or both of the motor 110 and/or the motor 106 under control signals sent by the controller 202. The clutch 108 may be opened or closed as desired. Dashed line 302 illustrates the driving of the wheels by motor 110 (or in some cases by motor 110 and motor 106, with clutch 108 engaged as needed) and possible regenerative braking. In the AEM mode, the clutch 104 may not be engaged, and thus the engine 102 may remain in a deactivated (OFF) state. Depending ON the desired state (e.g., driver power and/or torque demand), the electric machine 106 may be in an activated (ON) or deactivated (OFF) state with the clutch 108 engaged or disengaged as appropriate (as indicated by dashed line 303).

Fig. 3B shows the PMM1 mode. In this mode, both

clutches

104 and 108 are engaged and the engine 102 may be placed in an activated (ON) state and provide driving power to the wheels. The electric machine 106 and/or the electric machine 110 may be in an activated (ON) or deactivated (OFF) state depending ON the power and/or torque requested by the driver, the SOC of the battery, or any other desired state monitored and/or controlled by the controller 202.

Fig. 3C shows the PMM2 mode. In this mode, clutch 104 may be engaged and clutch 108 may be disengaged. With the clutch 104 engaged, the engine 102 may be active and drive the electric machine 106 as a generator to provide electrical energy to the battery (as indicated by dashed line 310). In addition, the motor 110 may be in an activated state and provide driving power to the wheels according to a desired state generated by the controller.

In another embodiment, the electric machine 106 may be driven by the engine 102 and provide electrical energy directly to the electric machine 110 (as indicated by dashed line 313) when the clutch 108 is open. This may be desirable when it is not possible or desirable to convert electrical energy of the motor 106 to chemical energy within the battery.

During PMM2, engine torque and speed may be designed to run on an ideal operating curve (IOL) or not at all while running. Controller 202 (or any other suitable controller) may determine which mode to operate in and when to switch to another mode based on a set of desired states. In one embodiment, the PMM2 mode may operate at any vehicle speed from zero to a maximum AEM speed. The AEM mode may be used in a range from zero speed to some minimum threshold according to desired control rules. The maximum speed in the AEM may not be as high as the PMM 1. In one embodiment, the PMM1 may be operated above a certain threshold speed and used for highway driving and to obtain optimal fuel efficiency.

An accelerator pedal (accelerator pedal) for an HEV or PHEV needs to control torque or power of the vehicle according to vehicle speed and motor characteristics. The driver desired torque (T) and/or desired power (P) may be determined by characteristics of the electric machine and PM. Specifically, the angular velocity (corner speed) at which the constant torque characteristic intersects the constant power characteristic is a curve defining the motor and may be added to the torque-rotation speed characteristic of the PM.

Embodiments of AEM mode

As noted above, the AEM mode is desired for low speed, zero emissions operation, where substantially all of the drive power is from electrical power. For PHEV embodiments, such electrical energy may be obtained from outside the vehicle (e.g., from a public or private power grid) or from an on-board generator, such as from liquid fuel. It may be desirable to use offboard power because it may be more efficient and provide electrical energy with zero emissions from the vehicle. The AEM mode may be achieved in the configuration of fig. 1 by using only motor 110 or by closing clutch 108 and using

motors

106 and 110 with clutch 104 in the open state. When only the motor 110 is used, the clutch 108 can be opened or closed because the motor 106 can be controlled to provide zero torque or zero power at any speed.

In the AEM mode, both

motors

106 and 110 may be used for operation in embodiments where final drive 120 includes a differential (but not necessarily with another variable-ratio transmission, such as an automatic transmission, CVT, etc.). Only the electric motor 110 may provide the vehicle 100 with driving power at certain points in time within a given driving cycle, particularly at low speeds, and up to a given efficiency of the electric motor 110. However, if the driver requires more power and/or torque, or if the driving conditions so require, the motor 106 may provide drive power simultaneously with the motor 110. In this case, it may be desirable for the controller 202 to operate the

motors

106 and 110 to have the

motors

106 and 110 work together with better efficiency than using either motor alone.

In one embodiment, it may be desirable to have one or both motors operate substantially on their respective IOLs while the vehicle is operating. Without a variable ratio transmission, then one electric machine can be used to control the vehicle in torque mode. If there are two motors in parallel, one embodiment may tend to be able to meet a particular torque request in time for the motor that has the best efficiency at that instant. Since the two motors are located on the same or parallel shafts, this switching can be performed substantially immediately or with a slight delay by electronic control.

The vehicle 100 may start in the AEM mode starting from zero speed, or if the engine 102 is running, the controller 202 may increase the engine torque by slipping the clutch while controlling the engine speed. Controller 202 may select the initial acceleration torque based on a request placed by the driver via the accelerator pedal. For low accelerator pedal starting, the motor 106 may be used, particularly if the motor 106 is designed to have a lower torque and/or power specification than the motor 110. In this case, the clutch 108 should be closed. Thus, the vehicle may be launched with the electric machine 106 or the electric machine 110 or the electric machine 106 plus the electric machine 110 (e.g., in a high torque/high traction electric mode). Such a high torque/high traction electric mode may also be used when the vehicle is at some non-zero speed and the driver commands additional power and/or torque as needed.

Fig. 4A shows a possible mapping 400 of torque-to-speed characteristics for a small motor (shown as dashed line 406) and a large motor (shown as solid line 408). Additionally, their corresponding envelope curves for the exemplary vehicle are shown given as envelope curves 404 and 402, respectively.

With this mapping, the relative efficiency of the vehicle can be determined by the instantaneous power required and the instantaneous power provided by electric machines 1(106) and 2 (110). For example, in fig. 4A, substantially the same efficiency can be obtained using motor 1 or 2 if the torque or power demand is as indicated by point 410. So that either motor can be used at this point. However, if at that time the operating point 410 shows that the torque and/or power is high, then the use of the electric machine 2(110) should be preferred. If the torque at point 410 is low, then motor 1(106) should preferably be used. The difference may become apparent as the required power or torque becomes lower.

This is also further illustrated in fig. 4A. Assuming that point a is the desired operating point requested by the accelerator pedal, then if the accelerator pedal is depressed further to request torque and power at point B, the motor 1 can be used later, since the motor 1 behaves more efficiently at that point. If the accelerator pedal is depressed further to power point C, the motor 2 can be used with motor 1 set to zero torque, since this configuration is more efficient at this point. It should be appreciated that at certain operating points, it may be more efficient to use some combination of drive power from motor 1(M1) and motor 2(M2), e.g., (a x M1) + (b x M2), for better efficiency, where a and b are determined by the corresponding efficiencies of M1 and M2. Finally, if the accelerator pedal is retracted to the power represented by point D on the motor map, then only motor M1 is used, as this is more efficient.

It should be appreciated that the motor efficiency information shown in fig. 4A may be determined by specification, testing, etc. of the motor. This information may be provided to the controller in various forms-for example, into a look-up table (LUT) or may be determined by modeling and calculation. In any embodiment, the motor efficiency data may be provided to the controller to make such switching decisions based on any performance metric desired.

In embodiments where the final drive includes a variable ratio gearbox (e.g., a mechanical CVT, an electronic CVT, an automatic gearbox, a manual gearbox, a planetary gear set, etc.), the motor 110 may be controlled by the controller 202 (or any other suitable controller within the system) to operate on its IOL at substantially all points in its operation. In such vehicles provided with some kind of variable ratio gearbox, the control of the vehicle may be as described in us patents (1)5842534, (2)6054844, (3)6116363, (4)6809429, (5)6847189, (6)6931850, (7)7217205, (8)7261672, (9)7713166, all of which are hereby incorporated by reference in their entirety.

Fig. 4B presents one possible embodiment of a control algorithm/flow diagram for operating a dual motor drive vehicle such as that shown in fig. 2. It should be appreciated that such a control algorithm may be applicable to a purely electric vehicle equipped with at least two electric machines, i.e., without an ICE/gas engine.

The control algorithm 450 may begin at 452 by determining the maximum torque limits of M1 and M2, and possibly also a performance envelope curve and an efficiency island. This information may be the code mapped in FIG. 4A and stored in electronic memory accessible to one or more controllers/processors disposed in the power system, such as shown in FIG. 2. As previously mentioned, each of these controllers has electronic memory accessible and this information can be stored in a variety of formats, including look-up tables (LUTs) or by modeling and computational determination of motor performance envelope curves and/or efficiency islands encoding.

The control algorithm may additionally adjust this information based on various sensor inputs such as current motor speed, temperature readings from various locations (e.g., ambient air temperature, operating temperature of M1, M2, engine, battery, or other locations related to motor/vehicle efficiency), voltage, current, etc.

At 454, the control algorithm may receive a torque request from the driver from any source, such as an accelerator pedal, a brake pedal, other torque requests from an electronic source, and the like. These torque demand signals are input into the processing module 454 and the module may determine the space of allowable torque combinations/configurations of M1 and M2 that are able to meet a given torque demand.

The module 456 may then find the best torque combination of M1 and M2 that has the highest efficiency (or meets some other desired metric for vehicle operation). This may be accomplished by traversing the space of allowable combinations and performing some minimum/maximum computation, such as traversing the efficiency map and gradients seen in fig. 4A. Once it is determined that the best combination of M1 and M2 is found to meet the torque demands, the torque demand signals for M1 and M2 may be sent to the associated controller to achieve these respective torque demands.

Embodiments of PMM parallel mode

In PMM parallel operation (as shown in FIG. 3B), both clutch 104 and clutch 108 are closed, and the engine and the two electric machines may all be directly connected to the final drive and wheels. In one embodiment, the motor 102 may be controlled on its IOL by the controller 202, as described above in PMM series mode.

To maintain the battery, the motor/generator 106 may be used to add the incremental power needed to maintain the battery's SOC for the next time increment, e.g., 60 seconds, while the motor 110 may be used to supplement the power of the engine 102 to provide acceleration and power. In one embodiment, since the engine 102 may be directly connected to the final drive gear set that drives the wheels, it may not be desirable to implement the PMM parallel mode until a minimum threshold speed is reached. Such a threshold speed may be set as a compromise after taking into account fuel economy and performance, and drive system smoothness. In one embodiment, the threshold speed for this mode may be set at about 30 km/h, depending on the vehicle and its specifications.

This mode may be more mechanically efficient than the PMM series mode since the engine 102 is directly driving the wheels during many portions of the driving cycle. However, in embodiments without a gearbox between the engine and final drive, it may be necessary to throttle the engine 102 to maintain the desired drive torque or power, so that more fuel may be used to generate the required power to drive the vehicle and maintain the battery. In such a case, there may be a difference in fuel efficiency between the PMM series mode and the PMM parallel mode. The controller 202 may determine this difference by continuously monitoring the two modes. The slightly throttled engine 102 may also be more efficient than feeding energy into the battery and then retrieving it.

In one embodiment, it may be desirable to set the strategy for switching from series mode to parallel mode or vice versa based on the most efficient operating conditions over a period of time (e.g., the first 60 seconds). If controller 202 determines that the first 60 seconds may use less fuel through the other mode, controller 202 may switch modes at the next 60 seconds. To avoid shifting between modes too frequently, an optional delay may be added.

Embodiments of PMM tandem mode

In PMM series operation (as shown in fig. 3C), the clutch 108 is open, and the electric machine 106 may act as a generator to generate power for the electric machine and maintain the battery within a desired range. Thus, the clutch 108 may be rarely used in the open state. This strategy may allow for less use of clutch release bearings. In addition, this may tend to extend the life as needed to meet the durability requirements of the vehicle.

This condition may occur if the battery has been depleted to its minimum SOC by driving the vehicle and the vehicle is at a low speed (e.g., below 50 km/h). In this case, the clutch 108 may be open and the vehicle may be placed in a series operating mode or PMM2 mode, where power from the PM and generator M1 may be used to charge the battery and drive the vehicle. The division of power may depend on the torque required by the PM and the charging strategy. Additional power may also be required for accessory loads and the like. The PM may run on its IOL for generating the total power required at that time. The recharge strategy may depend on the control strategy for recharging set into the program of the controller 202. In general, one feasible strategy may be to recharge to the upper limit of the SOC at the slowest possible depending on the driving regime requirements. In PMM2 or series mode, vehicle speed may be zero to a maximum maintained by electric machine 110. In one embodiment, the motor 110 may be controlled substantially as in the AEM mode. The PM (e.g., engine 102) may operate along its IOL as shown in fig. 3C and under the direction of the controller to provide the driver-requested power (e.g., by closing clutch 104) and to provide a power source to maintain the battery.

In another embodiment, the controller may control the engine 102 and the electric machine 106 to charge the battery with suitable power to maintain a desired SOC in the battery during the current driving cycle. Thus, for example, the power demanded by the driver/vehicle may be 50kW at a particular instant, then the IC engine and generator may be set to generate 50kW plus the additional power increase required to maintain the battery for a predetermined period of time according to a priori known travel cycle measurements.

Continuing with the present example, the time period may be determined to be, for example, a minimum of 10kW to charge the battery to the high SOC in 60 seconds. The engine 102 and motor/generator 106 may be set at 60kW until the battery reaches a predetermined high SOC, respectively. However, if the threshold is not reached within the desired time period, the delta power required to maintain the SOC for the next 60 seconds may be increased by an expected (e.g., proportional) amount based on the deviation value. In this way, the SOC is maintained automatically, regardless of how the driver is acting and how the terrain or driving cycle is requested.

In another embodiment, if the driver demand is determined by the controller 202 to be unreasonable (e.g., if the driver is hard on the accelerator pedal and hard on the brake pedal and may have a high cycle frequency, as may be detected by the controller from the pedal detection sensor), then an indication may be sent to the driver to signal that more fuel is being consumed than is reasonably expected. The indicator may be in the form of a bar graph or other proportional visual indicator that the driver is not anticipating traffic and is wasting energy. In another embodiment, controller 202 may dynamically change the setting of the accelerator pedal to limit the instantaneous desired acceleration rate and power. This may be used as an economy mode for the vehicle, and such economy mode may be selected by the driver to help conserve fuel. It is also possible to display the difference in fuel consumption per kilometer so that the driver can see the difference in fuel consumption in real time through such selection.

Further dynamic operating mode selection/control

As described above, the AEM is a viable operating mode for a pure EV equipped with two or more motor drives or a plug-in hybrid electric vehicle (PHEV) such as that shown in FIGS. 1 and 2. For a PHEV, the number of possible operating modes should be increased due to the opportunity to use a gas engine or other ICE to provide driving power. Fig. 5A and 5B are two embodiments of allowable operating mode spaces for various vehicles as described herein. FIG. 5A illustrates an operating mode space on a state of charge (SOC) versus vehicle speed grid 500. As can be seen, if substantially the SOC is high enough, the vehicle tends to use more of the electrical energy stored in the battery (rather than other power, gas engine, etc.).

This may be illustrated with an exemplary histogram to the left of the grid 500. As can be seen, if the system indicates that the SOC is high (i.e., greater than or equal to the "SOC _ high" threshold), the system may be inclined to operate in a "charge depleting" mode. In this mode, the system may preferentially operate with AEM 502 (but may operate in series, parallel, or some other mode of operation for the different scenarios described herein). Alternatively, if the system indicates that the SOC is low (i.e., less than the "SOC _ high" threshold), the system may be biased to operate in a "charge-sustaining" mode. In this mode, the system may preferentially operate in the parallel hybrid mode 504, the series hybrid mode 506, or some combination of modes (but may operate in the AEM for a limited period of time for different situations).

It should be appreciated that for a vehicle that is prioritized for operation in the charge-depleting operating mode, the SOC is substantially greater than or equal to the SOC _ high threshold as the first threshold. In addition, for a vehicle that is preferentially operated in the charge-sustaining mode of operation, the SOC may be less than or equal to the SOC _ high threshold as the second threshold. The first and second thresholds may be substantially the same threshold (i.e., SOC _ high). However, in other embodiments, the first and second thresholds may be different SOC values. This may be desirable from the standpoint of reducing switching between operating modes used by the vehicle. In other embodiments, the first and second thresholds may be functionally related to vehicle speed or other vehicle conditions (e.g., battery state of health, driver demand, etc.) and the SOC of the battery.

Additionally, it can be seen that at some point where the SOC is sufficiently low, the system can switch between AEM 502 and parallel hybrid mode 504. At the lower SOC point, the system may dynamically switch between series hybrid mode 506 and parallel hybrid mode 504. As shown in fig. 5A, the switching may be performed according to the vehicle speed and also according to the SOC. Other switching conditions are also possible. For example, the switching mode may also depend on the driver's torque request, traffic pattern, state of health of the battery, speed of the drive shaft, etc.

FIG. 5B is another embodiment of an operating mode feasible space (550) that may be used for a suitable vehicle. As can be seen, the space 550 can operate in a combination of AEM and series mode 552 at low speed/sufficiently high SOC. At higher speeds, the system may switch to a combination of series and parallel modes 554. At sufficiently high speeds, the system may preferentially operate in parallel mode 556.

As can also be seen, there may be an envelope curve 560 that determines a "minimum SOC" region 558 below which the system may be operated in a mode where the engine is on and the system is attempting to add energy back to the battery. This may limit the amount of switching between modes by the system controller. Above the minimum SOC line, there may be another envelope curve 562 that distinguishes between "charge retention" regions and "charge consumption" modes. In the charge-sustaining region, the system may be inclined to select a mode of increasing and/or conserving energy in the battery. In charge-depleting mode, the system may prefer to select a mode that uses the energy in the battery preferentially over the liquid fuel on-board the vehicle.

It can also be seen that the system can optionally raise the envelope curve upwards as the speed increases. Thus, at higher speeds, the system may dynamically adjust the envelope curve to favor mode switching at higher SOC levels. This can be used to compensate for faster energy usage rates at higher vehicle speeds.

One embodiment

FIG. 6 is one possible flow diagram embodiment for implementing dynamic switching between the disclosed modes of operation. It should be appreciated that there are other possible control algorithm implementations, such as those used in fig. 5A and 5B above, and that the present application contemplates all such suitable control algorithms.

At 602, the system and/or controller may read all system inputs including SOC, SOH, vehicle speed, engine temperature, etc. from sensors, etc., as previously described. At 604, the controller may make a determination as to whether the SOC is at a sufficiently high level (e.g., SOC > SOC _ high). If the answer is yes, then the system/controller may select AEM 614 (or high-tractive-effort electric mode if desired). If the answer is no, then a determination may be made as to whether the engine has a sufficiently high temperature 606. If the answer is yes, the system/controller may select the series hybrid mode 616. If the answer is no, a determination may be made as to whether the SOC is above a minimum SOC (SOC > SOC _ Low), and the vehicle may also be temporarily operated in PMM2 or series mode to warm the engine to its operating range. If the answer is yes, then a determination may be made at 612 as to whether the vehicle speed is above a certain threshold. If the answer is yes, then the system/controller may select an AEM at 618. If the answer is no, the system/controller may select the parallel hybrid mode 620.

If the determination at 608 indicates that the SOC is not at a level greater than or equal to the threshold, another determination may be made at 610 to determine whether the vehicle speed is above a certain threshold. If the answer is yes, then the system/controller may select the parallel hybrid mode 622. If the answer is no, the system/controller may select the series hybrid mode 624.

It should be appreciated that the threshold values themselves for various states (e.g., SOC, vehicle speed) may vary depending on the state of the vehicle.

Dynamic operation/mode conversion

Fig. 7 and 8 show two examples of dynamic operation in the control algorithm as described herein. Fig. 7 shows an exemplary driving cycle in two graphs. The upper diagram shows the rotational speeds of the electric machine 1, the electric machine 2 and the engine over a time segment. The lower graph shows vehicle speed over the same time segment (associated with the RPM of the drive shaft). The above figures illustrate how one control algorithm embodiment matches and switches the operating modes of the vehicle based on the travel cycle.

At 702, during a time segment from zero to about 440 seconds, it can be seen that the controller has selected a parallel mode for the vehicle. During this time, the rotational speeds of the electric machine 1, the electric machine 2 and the engine are matched, since they all run on the same drive shaft, with both clutches closed. At point 704, the system/controller detects that the user commands the vehicle to stop. However, the system/controller may be required to switch to series mode between 440 seconds and 480 seconds, taking into account the SOC or other appropriate conditions.

At this time, the engine and the motor 1 can be separated from the motor 2. Thus, the engine and the electric machine 1 can continue to operate along the curve 708 to generate electric energy to be sent back to the battery. At the same time, the motor 2 may continue to run along curve 706 to stop the vehicle or freewheel. At about 470 seconds, it can be seen that the user commands the vehicle to accelerate and the motor 2 responds to speed up the vehicle. The PM (e.g., the engine 102) and the motor 1 may run along its IOL to power the motor 2 as well as to provide additional power for maintaining the battery.

At point 710, it can be seen that the system/controller needs to be switched to parallel mode for around 480 seconds. In this case, it is necessary to engage the clutch 108 to engage the engine and motor 1 with the remainder of the drive shaft to power the wheels directly. It is now necessary to have the speed at which the drive shaft is disengaged from the motor 1 substantially match the starting speed of the drive shaft at the motor 2. Thus, for example, for smooth transitions, the rotational speeds of the engine and the electric machine 1 are slowed to a substantially matching degree and the clutch 108 is closed. For the remainder of fig. 7, it can be seen that the system/controller operates and switches the operating mode of the vehicle in a similar manner.

FIG. 8 is an exemplary travel cycle chart similar to FIG. 7. In fig. 8, the system/controller switches primarily between aem (ev) mode and parallel mode. As can be seen at 802, the vehicle is operating in parallel mode and the rotational speeds of the electric machine 1, the electric machine 2 and the engine are matched because they are all engaged on the main drive shaft. At point 804, the system/controller switches from the parallel mode to the AEM mode at approximately 1277 seconds. As can be seen, the clutch 108 is open and the engine and motor 1 go to zero speed (i.e., stop). In this process, the electric machine 1 may be actively torque or speed controlled to reduce engine-off vibrations.

The vehicle may be driven by the motor 2 and at approximately 1290 to 1296 seconds the system/controller detects a condition (e.g. torque requested by the user) to ensure switching to the parallel mode. At point 808, the engine can be seen being started by motor 1, with clutch 104 closed and clutch 108 open. At this time, the rotational speeds of the engine and the motor 1 at this time can be controlled to match the rotational speed of the motor 2 (or the drive shaft) (because the motor 1 has been disengaged from the drive shaft). During speed synchronization, the clutch 108 is closed and the engine is available to provide torque to the drive shaft with substantially no or little torque disturbance to the drive shaft.

Another embodiment

To control the mode transition as shown in fig. 7 and 8, the controller may possess an algorithm for determining the mode action and transition. In one embodiment shown in FIG. 9, the controller may have a state machine that defines hybrid system "permanent states (or modes)" such as full electric mode 904, series hybrid mode 906, parallel hybrid mode 908, and fault mode 910. The powertrain system typically operates in one of these permanent modes until a mode transition triggering condition is detected and/or satisfied. The transition triggering condition from the source mode to the target mode may be designed according to a high level strategy as in fig. 5A,5B or fig. 6, for example. Prior to achieving the target perpetual mode, the powertrain transitions to transitional modes such as the AEM-PMM2 transitional mode 912, the PMM1-PMM2 transitional mode 914, and the AEM-PMM1 transitional mode 916. The transition mode is a temporary mode in which the powertrain may be controlled or configured to support operation in transitioning to the target mode. Transitions are only allowed after fault and diagnostic based checks are completed and a new powertrain mode request is satisfied. For example, points 704 and 710 in FIG. 7 correspond to the parallel-series (PMM1-PMM2) transition mode 1014.

Points

804 and 808 in fig. 8 correspond to the all-electric-parallel (AEM-PMM1) transition pattern 916 in fig. 9.

Fault tolerant policy

A fault algorithm may be implemented in each of the powertrain modes to detect whether a fault has occurred while the vehicle is operating in that mode. FIG. 9 is one embodiment of a control algorithm/state diagram to implement fault tolerance processing. Upon detection of a system fault, the powertrain transitions to a fault mode 910 to continue operating the vehicle in a safe manner. The failure mode may force the powertrain to operate at a reduced level, such as reducing motor torque. In some cases, if the severity of the fault is high and the vehicle is not allowed to travel, the fault mode may force the powertrain to stop operating completely. After the fault condition is resolved, the powertrain may be allowed to transition back to the appropriate permanent mode (904,906, and 908). One possible fault tolerant design is that if the system is operating in a transition mode (912,914 or 916) and the transition time before entering the target mode exceeds a predetermined threshold due to component aging, the system state transitions to the failure mode 910. The system may remain in the failure mode or transition back to the source mode depending on the severity of the failure.

It should be appreciated that there may be other situations that cause the system to assume a failure mode process. The following are examples of other such conditions/faults:

failure example 1: if the motor temperature sensor feedback is not normal (e.g., out of range fault), the system may enter fault mode operation 910. In this mode, the motor torque may be significantly reduced and a warning may be issued to the driver.

Failure example 2: in series mode (PMM2)906, if the system detects that motor 1 is not generating power (e.g., due to a motor 1 failure or engine failure), the series mode may be terminated and the fault mode may be entered. The failure mode may shut down the engine and run the vehicle electrically driven only by the electric machine 2. If the fault condition is relieved, the system may be allowed to resume full electric mode 904 for normal operation.

Failure example 3: if the clutch position cannot be confirmed from the sensor (e.g., due to sensor failure), the system may enter a failure mode 910. In the failure mode only the electric machine 2 can be used to drive the vehicle. No clutch actuation is allowed.

Advanced battery management embodiment

In another application of the present application, it may be desirable to incorporate appropriate battery management to improve battery life and performance. Although most batteries provided by battery manufacturers typically include a Battery Management System (BMS)119A, these BMS do not adequately and/or optimally manage vehicle batteries for HEVs/PHEVs. Thus, a typical BMS can provide information to a higher level controller (e.g., controller 202) and rely on that controller to further control secondary factors such as efficient use of electrical energy and maintenance of proper battery usage. Such an additional control system, a Battery Monitoring and Maintenance System (BMMS), may be implemented by the controller 202 shown in FIG. 1.

In one BMMS embodiment implemented according to the principles of the present application, when discharging a battery pack to generate the motive power required by the vehicle and the driver, it may be desirable to provide motive power to maximize the use of electrical energy while driving the vehicle in an AEM or PMM (e.g., PMM1 and/or PMM2) mode in order to promote healthy use of the battery to extend battery life. If the battery system has limitations on available power and/or current (as may be determined by the BMMS considering battery SOC), then the temperature and temperature profile, battery age, and other parameters may be considered by the BMMS (and/or the controller 202). The BMMS and/or controller 202 may limit power and/or current performance to protect the battery from sudden adverse impacts. Such an adverse impact may occur, for example, at the start of the vehicle. In this case, the controller 202 may actively control the current output of the battery and thus the motor output. In this embodiment, it is thus possible to achieve reduced performance compared to that achieved if such a restriction is not imposed. However, this performance limitation can translate into longer battery life and greater power range in vehicles driven in AEM or PMM modes.

It is known that all cells have internal resistance and that loss of internal resistance in the battery pack can cause the battery pack to heat. But the loss is proportional to I²Xr, where I is the current of the battery and R is the instantaneous internal resistance of the battery. Such internal resistance of the battery tends to vary depending on the type of battery, SOC, temperature, age, and the like. Thus, in one embodiment, the BMMS may regulate the discharge of the battery pack based on the state of health (SOH), state of charge (SOC), temperature, and other factors of the battery, as may be required to affect the life of the battery pack.

Additionally, when recharging the batteries within the vehicle via the vehicle's primary PM (e.g., engine 102, fuel cell) or other power generation device or kinetic energy of the vehicle during regenerative braking, the BMMS and/or controller 202 may determine a maximum current to meet the power required to maintain the driveline energy demand and charge the battery pack with a minimum current sufficient to replenish the amount of power consumed by the specified driving event. Such driving events may occur over a specified period of time, such as within the past "X" seconds, where X may be a function of the driving event, such as a crowded city road or mountain road trip. The current limit for such recharging may also be determined by the driving characteristics of the driver and the environmental conditions of the vehicle, such as traffic conditions, ambient temperature, etc.

In one embodiment, the control program may be integrated into the BMMS controller. FIG. 10 is one embodiment of an advanced battery management control strategy. FIG. 10 shows a coordinate grid of SOC versus vehicle speed and illustrates an exemplary travel cycle and speed profile 1006 that results in an instantaneous discharge. An average discharge and speed curve 1008 is derived from and plotted alongside curve 1006.

The driving cycle is managed and/or controlled between two SOC values, namely a maximum SOC cutoff envelope curve 1002 and a minimum SOC cutoff envelope curve 1004.

Curves

1002 and 1004 are illustrated as straight lines for purposes of illustration only, but it should be understood that other envelope curves are possible. Fig. 10 shows that the average vehicle speed is low when the battery is discharged (i.e., when the battery is shifted from the upper-limit state of charge to the lower-limit state of charge line) and the vehicle speed is high when the battery is charged. This is not always the case, but can be used to distinguish between taking energy from the battery and charging energy back into the battery. These states may be, for example, about the same speed. The division of the speed is to clarify the concept. The trace shows the change with the charge and discharge of the battery and the vehicle speed. The green line is the average trajectory of the discharge or charge. It should be noted that the discharge trajectory may be shorter in time than charging, since it may be desirable to charge as slowly as possible to significantly improve charging efficiency as well as reduce battery heating and enhance battery health. The charging time can be maximized by BMMS. FIG. 10 further illustrates that the threshold value may be a function of vehicle speed, since the energy required to propel the vehicle is a function of vehicle speed.

The upper SOC threshold 1002 and the lower SOC threshold 1004 may be straight lines or curves, which may be a function of vehicle speed and other parameters. Currently, hybrid vehicles tend to maintain a high SOC and a low SOC of a battery independent of speed. In one embodiment, the BMMS implements a curve or other dependency between these thresholds. In another embodiment, the BMMS may implement a curve or other dependency between (1) the different relationships between the high SOC threshold and the vehicle speed and (2) the low SOC threshold and the vehicle speed. These relationships may be determined by the requirements of the vehicle and the battery pack. The combination of curves for the range of the vehicle and the battery specifications may vary and may also depend on the application and possible driver instructions.

Embodiments based on driver characteristics

Driver demand can be measured by driver actuation of the accelerator and brake pedals. It is desirable to collect this information for feedback into the BMMS. In one embodiment, this may be accomplished by measuring the average accelerator and brake pedal actuation and the second moment of these pedal positions to determine the offset and frequency of actuation. This data may be used to determine the aggressiveness of the driver. Since the energy required to drive a particular vehicle speed profile tends to be proportional to the driver's actions, this statistical information can be used to determine the energy consumption or energy efficiency of the vehicle for each of the specified vehicle travel distances.

This information may be compared to "standard" or controlled test conditions and in one embodiment may display an indication with a time history to the driver to provide driver feedback regarding a more appropriate driving style. An indication of feasible modification may be provided to the driver to encourage him to minimize changes in the accelerator and brake pedals, thereby reducing power consumption and increasing power range and vehicle efficiency.

In addition, this information can be used to set the range of variation and the average state of charge (SOC) of the battery pack. In one embodiment, the more aggressive and frequent the accelerator and brake pedals are used, the higher the minimum SOC threshold may be set in order to avoid the battery SOC becoming too low during driving. This is done because the requirements of a road or other overload condition need to be met to allow the battery SOC to temporarily decrease outside of the lower bound. In one such example, crossing the lower boundary may be allowed if the accelerator pedal is depressed to a limit beyond a first time period (e.g., 5 seconds, etc.), for example, meaning that the driver continues to demand high power for that time period and thus may need to operate carefully to demand full power for the vehicle. Beyond this first time period, power may be reduced by a degradation strategy that does not compromise security but protects the battery, as will be discussed with reference to fig. 11 herein.

In another embodiment, the BMMS may also be used to notify the system when changing from AEM mode (e.g., power consumption) to series or parallel PMM (e.g., power retention) or vice versa. Since the average vehicle speed can be a determining factor for the energy used over time, this information in combination with the accelerator pedal demand can determine the power used. In one embodiment, speed and accelerator and brake pedal requirements can be used as inputs that can be used to determine the power required and the energy required over a particular period of time, provided that future actions are assumed to have the same statistical characteristics in terms of road load and driver behavior.

From this information it is possible to predict or estimate what the future time period (e.g., the next ten (10) seconds, etc.) may be. One strategy may be to use the same maximum power and energy for the first ten (10) seconds or any suitable period of time. It should be appreciated that other strategies may be used. For example, the prediction time and the data collection time need not be the same. Once the predicted value of the charging current is determined, the power levels of the engine and generator can then be determined. If the current level is too high for the current state of the battery (determined by the temperature, state of charge, state of health, etc. of the battery), then the performance of the vehicle may be limited by the vehicle controller. In the case of pure EVs, all vehicles that are driven only by battery packs may have limited performance under certain circumstances. The BMMS may limit performance in advance to protect the battery and provide the longest anticipated travel for battery only.

One embodiment

Figure 11 illustrates one embodiment of a dynamic BMMS control strategy that may be derived in accordance with the principles of the present application.

Fig. 11 is a map of vehicle speed and SOC. As can be seen, the BMMS module may dynamically select among several curves for high or low SOC thresholds. In one embodiment, the BMMS may set such charge and discharge limits based on battery demand rather than vehicle speed demand. The driver may not be able to discern these differences, but the battery is better protected.

There may be an optional adequate minimum allowable SOC at the bottom of this graph in fig. 11, below which the BMMS does not allow the battery to drain. If included in the BMMS, this value may be determined by a variety of factors, such as battery specifications, warranty factors, and the like. Other curves that can be achieved are: a high SOC threshold for charge retention (1108), a low SOC for large changes in acceleration and/or braking actions (1106), a low SOC for average acceleration and/or braking actions (1104), and a low SOC for small changes in acceleration and/or braking actions (1102). As described above, these profiles may be selected based on the driver's acceleration and/or braking actions and any identifiable associated statistical information (e.g., 1110).

The BMMS may determine that low speed travel in AEM mode may drain the battery to a minimum SOC boundary, and then the powertrain system should switch to PMM or series or parallel mode. To determine an appropriate SOC for a given vehicle speed, driver action, an average and standard distribution of speeds may be measured and/or calculated. In one embodiment, the low SOC may be set as small as possible based on these data. For example, if the average vehicle speed is below a certain speed (e.g., 30 km/h) and the speed variation is also small, the SOC may be set to this minimum allowed by battery durability and projected vehicle instantaneous power and energy considerations. However, if the speed changes too quickly indicating an emergency stop and start of traffic situation, the low SOC boundary should be set to a higher value to allow higher power to be used for a longer period of time. Such a situation may occur, for example, in road travel where the traffic flow is large.

When the vehicle is in a PMM state in charge-sustaining or series or parallel mode, the charge rate may be set to a minimum value determined by the vehicle state and battery characteristics described above. As described above, the charge rate may depend on vehicle motion and driver motion. The statistical information may be used to determine a charge rate for the battery pack and the average SOC and Δ SOC. It may be necessary to set the maximum SOC line and the minimum SOC line and the rated SOC or the intermediate SOC according to the vehicle speed. Then, based on the driving statistics, the high and low SOC lines can be modified to be narrower by the statistics. This narrowing may result in better maintenance of the battery and energizing the battery in a shorter stroke to thereby extend life.

An example

FIG. 12 illustrates an exemplary travel cycle and battery SOC control as a function of vehicle speed and time. Fig. 12 helps to describe BMMS control and mode switching. The vehicle mode shown here is AEM (or charge drain), where the battery can regenerate power by braking the vehicle. Fig. 12 also shows a series or parallel PMM charge retention mode.

As can be seen, the BMMS may optionally set a minimum SOC floor (1202) that is shown to avoid battery damage or protect warranty obligations.

Fig. 12 shows a map of the battery state of charge SOC, the vehicle speed, and time. Curve 1208 illustrates this exemplary travel cycle. The curve 1208 starts from the stopping point (vehicle speed ═ 0) and at high SOC. Since the vehicle is traveling in AEM mode, the battery is shown as being drained. The vehicle travels along the black line in the AEM mode until the battery SOC reaches the high SOC plane (1206) at point a. At this point, the vehicle may remain in AEM mode or change to PMM mode, but the battery may continue to drain to the low SOC plane at point B (1204).

At point B, the vehicle may switch to the PMM and the battery may be charged until the SOC again reaches the high SOC plane at point C. The battery may be drained again while being driven in the PMM mode or the AEM mode. In the case of a vehicle in a mountain road or continuously high load condition (e.g., pulling a trailer), the SOC may fall below the low SOC plane. This may be required to maintain performance or for safety reasons. However, for such high performance requirements, the battery may continue to discharge until a minimum SOC plane (1202) is reached, below which the battery is not allowed to fall.

In one embodiment, the vehicle controller may then alert the driver that he can no longer continue driving at this performance level and begin limiting performance to protect the battery. The vehicle may be slowed down to protect the battery as power may be reduced. The reduction in power may begin before the SOC floor is reached to alert the driver that the floor is approaching by gradually reducing the available power by some amount, for example by about 5% every 10 seconds.

FIG. 12 also helps to illustrate the relationship between the three planes high SOC, low SOC, and bottom surface. In one application, the BMMS strategy may be used to achieve minimum fuel consumption, and in one embodiment, the engine may be reduced to a minimum size to maintain constant speed travel on a flat road. The battery can reach the bottom surface without taking into account a slight change in the road or the road load, and the output power of the vehicle and the power performance of the vehicle can be reduced. The torque performance of the vehicle can be maintained by switching the gearbox to a higher reduction gear or a lower gear, if any.

In another embodiment, the "hybrid dynamics" or relative size of the engine and motor/battery pack may determine the potential minimum SOC and Δ SOC. For example, if the engine is minimized and the average power demand of the vehicle is high and the magnitude of the change is large, the minimum SOC should be set higher because the battery and the motor may need to be frequently depowered from the engine. If the engine or prime mover is large, the SOC may be set lower for longer all-electric range (AER), but the highway fuel economy of the vehicle in charge-sustaining mode may be lower due to the larger engine and thus less efficient operation of the engine.

In one embodiment, the vehicle may be designed such that when the engine is running, the engine should be large enough to carry a set full load on a level or near level road. The average SOC and Δ SOC should also be relatively large or dynamically increased when the possibility of continuously high loads arises, such as when driving on a mountain road or towing a trailer. The prime mover power must be large enough to meet the load at the required speed and the specific load and grade conditions for long periods or steady state. The engine may be further reduced, but accordingly may not be able to maintain speed for a long period of time for a particular load. A compromise must be made between the degree of mixing and the ability to maintain speed on level or minimum grade roads.

For example, the maximum speed of the vehicle may be determined by the sum of the power of the prime mover and the electric machine and the battery power. But how long this speed can be maintained can be determined by the specifications of the battery pack. After the battery pack is depleted to a minimum SOC determined by the battery program of the vehicle controller, the speed is gradually reduced to a speed that can be maintained by the engine alone. The hybrid dynamics are limited by the maintained vehicle speed.

The degree of mixing may also be used to determine battery size and motor size. The minimum cost may be determined by the minimum battery size and power. Optimal battery capacity (kwh) and power (kw) may be determined to meet performance requirements and cost targets. Optimization algorithms as a function of the driving expectations, the fuel economy expectations, and the acceleration performance specifications may be determined to minimize vehicle cost and oil consumption. A refund amount that saves 40% fuel on a standard vehicle regardless of hybrid dynamics may be an overall rule that can determine the required engine size.

The vehicle control strategy described above can be implemented to maximize the hybrid DOH of the vehicle, and also protect the battery from regions where the life and performance of the battery may be affected below that expected by the battery manufacturer.

In general, PHEVs may be used to replace fossil fuels and to enable the utilization of renewable energy. It may also be desirable to later use a larger stack that is capable of a longer AEM stroke. Thus, the utilization of renewable energy from local sun and wind can be integrated into a high DOH vehicle.

This concept may allow high DOH vehicles to replace most fossil fuels while still maintaining performance through the battery. This performance may not be maintained for too long, but the duration is still sufficient to meet the user's driving demand of over 90%. The few cases where performance drops below the low SOC plane and reaches the lowest level where performance may be curtailed should be as few as possible based on the specifications of the vehicle. If the frequency of reaching the bottom floor is frequent and the driver and owner require more performance, the PHEV may be equipped with a larger engine for this purpose. For PHEV manufacturers, a variety of vehicle variations may be provided, for example, having 3 or more engine sizes. It may also be desirable to provide 3 or more DOH configurations for the same vehicle. It should be noted that battery management may take DOH into account with the architecture as they all affect the robustness of the BMMS.

What has been described above includes examples of the subject invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the subject invention are possible. Accordingly, it is intended that the claimed subject matter embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.

In particular and in regard to the various functions performed by the above described components, devices, circuits, systems and the like, the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary implementations of the claimed subject matter. In this regard, it will also be recognized that the innovation includes a system as well as a computer-readable medium having computer-executable instructions for performing the acts and/or events of the various methods of the claimed subject matter.

In addition, while a particular feature of the subject invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "includes" and "including" and variants thereof are used in either the detailed description or the claims, such terms are to be understood as being inclusive in a manner similar to the term "comprising".

Claims

1. A method of controlling operation of a powertrain of a hybrid HEV vehicle, the HEV vehicle including a prime mover; a first motor-generator; a battery electrically connected to the first motor-generator, the battery configured to provide electrical energy to the first motor-generator; and a controller configured to receive signals from one or more sensors and provide control signals to the prime mover and the first motor-generator; the method comprises the following steps:

determining an energy usage pattern of a driver over time, the energy usage pattern comprising: the driver's action on an accelerator pedal and action on a brake pedal;

selecting a first state of charge (SOC) threshold curve among a set of SOC threshold curves, the first SOC threshold curve dependent on the energy usage pattern of the driver;

selecting an operating mode of the HEV based on SOC and vehicle speed;

selecting a second SOC threshold curve, higher than the first SOC threshold curve, to run the vehicle if the driver's energy usage pattern over time exhibits a first change over time in at least one of accelerator pedal actuation and brake pedal actuation; and

selecting a second SOC threshold curve lower than the first SOC threshold curve to run the vehicle if the driver's energy usage pattern over time exhibits a second change over time in at least one of accelerator pedal actuation and brake pedal actuation that is less than the first change.

2. The method of claim 1, wherein determining an energy usage pattern of the driver over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.

3. The method of claim 2, further comprising: driver demand information is displayed to give the driver advice to improve energy efficiency.

4. The method of claim 2, further comprising: predicting a future energy demand of the driver, and selecting an SOC threshold curve based on the prediction.

5. The method of claim 1, wherein the prime mover comprises a fuel cell.

6. The method of claim 5, wherein determining the driver's energy usage pattern over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.

7. The method of claim 1, wherein the powertrain for the HEV vehicle comprises: a first clutch through which the first motor-generator is mechanically connected to the prime mover; a second motor-generator and a second clutch, the second motor-generator being mechanically connected to the first motor-generator through the second clutch; the battery is electrically connected to the second motor-generator, the battery being configured to provide electrical energy to the second motor-generator; and the controller is configured to provide control signals to the first clutch, the second clutch, and the second motor-generator.

8. The method of claim 7, wherein determining an energy usage pattern of the driver over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.

9. A system for controlling operation of a powertrain of a hybrid HEV vehicle, the HEV vehicle including a prime mover; a first motor-generator; a battery electrically connected to the first motor-generator, the battery configured to provide electrical energy to the first motor-generator; and a controller configured to receive signals from one or more sensors and provide control signals to the prime mover and the first motor-generator; the controller executes the following computer-implemented instructions, including:

selecting an operating mode of the HEV based on SOC and vehicle speed;

10. The system of claim 9, wherein determining the driver's energy usage pattern over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.

11. The system of claim 10, further comprising: driver demand information is displayed to give the driver advice to improve energy efficiency.

12. The system of claim 10, further comprising: predicting a future energy demand of the driver, and selecting an SOC threshold curve based on the prediction.

13. The system of claim 9, wherein the prime mover comprises a fuel cell.

14. The system of claim 13, wherein determining the driver's energy usage pattern over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.

15. The system of claim 9, wherein the powertrain for the HEV vehicle comprises: a first clutch through which the first motor-generator is mechanically connected to the prime mover; a second motor-generator and a second clutch, the second motor-generator being mechanically connected to the first motor-generator through the second clutch; the battery is electrically connected to the second motor-generator, the battery being configured to provide electrical energy to the second motor-generator; and the controller is configured to provide control signals to the first clutch, the second clutch, and the second motor-generator.

16. The system of claim 15, wherein determining the driver's energy usage pattern over time further comprises: measuring an average accelerator pedal effort and an average brake pedal effort; and measuring a second torque of the accelerator pedal actuation and the brake pedal actuation.