Patent Publication Number: US-2004044448-A1

Title: Vehicle systems controller with modular architecture

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates to a vehicle systems controller having a modular architecture and more particularly, to a vehicle systems controller for use with a hybrid electric vehicle and having a modular architecture which is logically partitioned based upon vehicle functionality, thereby allowing for relatively quick and easy modification or replacement of vehicle control processes or features.  
       [0003] 2. Background of the Invention  
       [0004] Vehicle systems controllers (“VSCs”) are devices used within automotive vehicles, such as a hybrid electric vehicle (“HEV”), in order to control various vehicle systems, processes and functions and are often part of the powertrain controller. One type of hybrid electric vehicle, commonly referred to as a “power split” type hybrid electric vehicle, includes three powertrain subsystems which cooperatively provide the torque necessary to power the vehicle, and a vehicle system controller which controls the three subsystems. A “parallel-series” type hybrid electric vehicle includes an engine subsystem (e.g., an internal combustion engine and controller), a generator subsystem (e.g., a motor/generator and controller), and a motor subsystem or an “electric drive subsystem” (e.g., an electric motor and controller).  
       [0005] This hybrid configuration provides improved fuel economy, and reduced emissions since the internal combustion engine can be operated at its most efficient/preferred operating points by use of the various subsystems. Additionally, this configuration can achieve better driveability, and may extend vehicle performance relative to a comparative conventional vehicle. In order to achieve the goal, appropriate coordination and control between subsystems in the HEV are essential. This goal is achieved by use of the VSC and a hierarchical control architecture.  
       [0006] The VSC is typically used to interpret driver inputs (e.g., gear selection, accelerator position and braking effort), to coordinate each of the vehicle subsystems, and to determine the vehicle system operating state. The VSC generates commands to the appropriate subsystems based on driver inputs and control strategies, and sends the generated commands to the respective subsystems. The generated commands sent to the respective subsystems are effective to cause the subsystems to take appropriate actions to meet the driver&#39;s demands.  
       [0007] Due to the numerous types of vehicle subsystems and processes which may vary from vehicle to vehicle, conventional VSCs are relatively complex and are designed to serve and/or function within a specific type of vehicle. Due to this complexity and design, it is relatively difficult to modify a conventional VSC to operate with a new vehicle system or functionality. For example and without limitation, if one were to replace the braking system or functionality within an HEV having a conventional VSC with a different type of system of functionality (e.g., series versus parallel regenerative braking), many control features within the powertrain controller would have to be modified or reprogrammed. This increases the cost and time required to make such a modification. Moreover, each different type of HEV typically requires a VSC with a somewhat different functionality, thereby reducing the uniformity among HEVs and increasing the overall cost of the HEVs.  
       [0008] There is therefore a need for a modular VSC which is partitioned into portions which corresponds to and/or provide a logical grouping of vehicle functions, thereby allowing the VSC to be easily modified to conform to new vehicle functions or features.  
       SUMMARY OF THE INVENTION  
       [0009] A first non-limiting advantage of the present invention is that the present invention provides a vehicle system controller (“VSC”) for a hybrid electric vehicle (“HEV”) which overcomes at least some of the previously delineated drawbacks of prior VSCs or powertrain controllers.  
       [0010] A second non-limiting advantage of the present invention is that the present invention provides a modular VSC which includes various portions which correspond to a logical grouping of vehicle functions, thereby allowing the vehicle functionality to be relatively easily modified.  
       [0011] A third non-limiting advantage of the present invention is that the present invention provides a VSC that is partitioned to take into account a logical grouping of vehicle functions, while maintaining a hierarchy of control within the VSC.  
       [0012] According to a first aspect of the present invention, a modular vehicle system controller is provided for use with a hybrid electric vehicle. The modular vehicle system controller includes a plurality of portions, wherein each of the plurality of portions corresponds to a certain vehicle functionality.  
       [0013] According to a second aspect of the present invention, a method of organizing a vehicle system controller for use with a hybrid electric vehicle is provided. The method includes the step of partitioning the controller into a plurality of control portions, each of the plurality of control portions corresponding to a particular vehicle functionality.  
       [0014] Further objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred embodiment of the invention and by reference to the following drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 is a block diagram of a hybrid electric vehicle which includes a vehicle system controller which is made in accordance with the teachings of a preferred embodiment of the present invention.  
     [0016]FIG. 2 is a block diagram illustrating the vehicle system controller architecture which is utilized within the hybrid electric vehicle shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION  
     [0017] Referring now to FIG. 1, there is shown an automotive hybrid electric vehicle  10  having a powertrain, propulsion or drive system  12  and a modular vehicle system controller  40  which is made in accordance with the teachings of the preferred embodiment of the present invention. As should be appreciated to those of ordinary skill in the art, propulsion system  12  is a “parallel-series” type propulsion system, and includes an internal combustion engine  14 , an electric generator/motor  16 , and a motor subsystem  18 . While the modular vehicle system controller  40  of the preferred embodiment of the invention is described as being used with a power split type HEV, it should be appreciated that the modular controller  40  is capable of controlling various other drive system configurations and methodologies.  
     [0018] The engine  14  and generator  16  are interconnected by use of a conventional planetary gear set  20 , including a carrier  22 , a sun gear  24  and a ring gear  26 , which is operatively coupled to drive line  28 . System  12  further includes a conventional one-way clutch  30  which is operatively coupled to the output shaft  32  of engine  14 , and a brake or clutch assembly  34  which is operatively coupled to generator  16 . A conventional electrical energy storage device  36  (e.g., a battery or other electrical energy storage device) is operatively coupled to generator  16  and motor  18 . Battery  36  receives and provides power from/to generator  16  and provides power to/from motor  18 .  
     [0019] In the preferred embodiment of the invention, the engine  14  is a conventional internal combustion engine, and is physically and operatively coupled to the carrier  22  of the planetary gear set  20 . Generator  16  is a conventional motor/generator and is physically and operatively coupled to the sun gear  24  of the planetary gear set  20 . Planetary gear set  20  allows engine  14  and generator  16  to selectively cooperate as a “single power source” which provides a power or torque output from the ring gear  26  of the planetary gear set  20  to the drive line  28 . It should be appreciated that planetary gear set  20  further serves as a power split device that splits the output from engine  14  to the generator  16  and to the drive line  28 , and as a continuous variable transmission (CVT) between the engine  14  and the ring gear  26 , which is operatively coupled to and drives the wheels of vehicle  10 .  
     [0020] The electric motor  18  is a conventional electric motor which acts as a “second power source” that provides torque and power to the vehicle drive line  28  independently from the first power source (i.e., engine  14  and generator  16 ). In this manner, the two power sources (i.e., the internal combustion engine  14  generator  16  and the electric motor  18 ) can cooperatively deliver torque and power to the vehicle  10  simultaneously and/or independently.  
     [0021] Referring now to FIG. 2; there is illustrated the vehicle system controller  40  which is employed within vehicle  10 . In the preferred embodiment of the invention, the vehicle system controller (“VSC”)  40  is electrically and communicatively coupled to conventional user or driver operated controls or components  42 , to one or more conventional vehicle operating condition sensors  44 , and to subsystem controllers  46 - 52  by way of a conventional bus or other electrical signal routing assembly. Controller  40  receives signals and/or commands generated by driver inputs, vehicle operating condition sensors (e.g., gear selection, accelerator position, and braking effort), and subsystem controllers (i.e., feedback) and processes and utilizes the received signals to determine the amount of torque which is to be provided to the vehicle&#39;s drive train  28  and to generate commands to the appropriate subsystems or controllers  46 - 52  to selectively provide the desired torque to the drive train  28  and to provide the requisite functionality to vehicle  10 .  
     [0022] Each subsystem  46 - 52  includes or shares one or more microprocessors as well as other chips and integrated circuits which cooperatively control the operation of vehicle  10 . In the preferred embodiment, controller  46  comprises a conventional battery controller, controller  48  comprises a conventional transaxle controller for controlling the electric motor  18  and generator  16  (i.e., the electrical components of the transaxle) of vehicle  10 , controller  50  comprises a conventional engine controller, and controller  52  comprises a conventional braking controller which includes a conventional friction braking system (e.g., a hydraulically actuated system) and an anti-lock braking system. In the preferred embodiment, VSC  40  shares a microprocessor with at least one of controllers  46 - 52  (e.g., VSC  40  and engine controller  50  share a microprocessor) in order to reduce cost and decrease packaging size.  
     [0023] VSC  40  receives feedback from each of controllers  46 - 52  and uses the received feedback along with commands from driver inputs  42  and signals from sensors  44  to generate control commands to the relevant controllers  46 - 52  and the vehicle&#39;s instrument panel or cluster assembly  54 . VSC  40  is effective to determine the total amount of torque which is to be provided or delivered to drive train  28  and to partition or divide the total amount of torque between the various subsystems (e.g., divides the torque between the power source, transmission assembly, and braking assembly). The commands, signals and feedback received and provided by VSC  40  are described below.  
     [0024] Driver operated controls  42  provide several commands to VSC  40 . Particularly, driver operated controls  42  provide an ignition key command representing the state or position of the ignition key (i.e., OFF, START, RUN, ACCESSORIES), gear shifter commands representing the desired gear engagement of vehicle  10  (i.e., Park, Reverse, Neutral, Drive, and Low or PRNDL), accelerator and brake pedal commands, cruise control commands, and air conditioning commands. Vehicle sensors  44  provide vehicle attribute data to VSC  40 , such as vehicle speed data, DC/DC converter operating condition data and other vehicle operating attribute data. Battery controller  46  provides feedback to VSC  40  from battery  36 , such as an estimation of the battery&#39;s state of charge, battery voltage data, battery limits data, battery operating status data (e.g., recharging), and battery fault data. Transaxle controller  48  provides feedback to VSC  40  from the transaxle (i.e., motor  18  and generator  16 ), such as estimated torque values provided by motor  18  and generator  16 , motor/generator speed values, limits values, motor/generator status data, and motor/generator fault data. Engine controller  50  provides feedback to VSC  40  from engine  14 , such as estimated engine-produced torque, engine speed, engine limits data, engine operating status, and engine fault data. Brake controller  52  provides feedback to VSC  40  from the braking assemblies or system  38 , such as negative torque request data, anti-lock braking system status and operating data, braking system status data, and braking system fault data.  
     [0025] In the control system architecture, the VSC  40  is the “superior” controller, with subsystems  46   54  (i.e., controllers  46   52  and instrument cluster  54 ) acting as “subordinate” controllers or assemblies. Exceptions may exist to allow one or more of subsystems  46   54  to override a command from VSC  40  with a “peer” subsystem command (e.g., a command from another of subsystems  46   54 ) under certain predetermined conditions. In such instances, each subsystem  46   54  communicates with the VSC  40  to inform the VSC  40  of the actual action undertaken which deviates from the VSC commanded action. Each subsystem  46   54  further communicates a signal to VSC  40  when one or more faults are detected in the respective subsystem  46   54 , thereby notifying VSC  40  that a fault condition is present. Fault conditions, in another non-limiting embodiment, may also be communicated to a driver of vehicle  10  through instrument cluster assembly  54 .  
     [0026] As shown in FIG. 2, the VSC  40  is modular and is composed of different control portions  56 - 70  which correspond to certain vehicle functions or features. Each portion may represent a removable hardware and/or software segment, portion or device of the VSC  40  which is electrically and/or communicatively interconnected with the other portions of VSC  40 . The partitioning of the vehicle features within the VSC  40  provides a logical grouping of functions and also takes into account the hierarchy of control within the VSC  40 . The architecture of VSC  40  also enables relatively easy replacement of one type of functionality for another (e.g., series versus parallel regenerative braking). Particularly, a certain vehicle functionality may be replaced by removing (e.g., disconnecting or deleting) a certain portion of controller  40  and installing (e.g., connecting or loading) a replacement portion which provides the desired functionality.  
     [0027] In the preferred embodiment of the invention, control portion  56  provides a vehicle mode control process; control portion  58  provides an output torque requestor control process; control portion  60  provides a battery management control process; control portion  62  provides a driver information control process; control portion  64  provides an energy management control process; control portion  66  provides a brake system control process; control portion  68  provides an engine start/stop control process and control portion  70  provides a torque estimation control process.  
     [0028] Vehicle mode control portion  56  determines the operating mode for the VSC  40 . Portion  56  comprises the “top layer” controller for complete powertrain control. Portion  56  communicates the operating mode of the vehicle, as determined by the ignition key position (e.g., OFF, RUN, START, ACCESSORIES), to the other control processes or portions  58 - 70 , that the other portions  58 - 70  may function according to the current vehicle mode. Portion  56  further checks each system  46 - 52  for faults prior to starting and stopping the vehicle  10  and during vehicle  10  operation. In providing these functions, portion  56  checks to make sure the other processes  58 - 70  respond to its commands before proceeding. When a fault is detected within any of the vehicle components (e.g., within the engine  14 , generator  16 , traction motor  18 , or battery  36 ) portion  56  either selects a limited operating strategy (“LOS”) mode with which to operate the remaining functional powertrain components or shuts down the vehicle  10 .  
     [0029] Output torque requestor control portion  58  receives and handles all torque commands from requesting devices within the vehicle  10  (e.g., accelerator pedal, brake pedal, cruise control system, traction control system), and determines the final wheel torque (positive or negative) that the powertrain and regenerative braking system must produce. In order to provide this determination, portion  58  combines the driver demands from the accelerator and brake pedal, and arbitrates from other “torque requesters” such as cruise control, traction control (if program required), interactive vehicle dynamics, and vehicle speed limiting systems. Based upon the signals received from all requestors, portion  58  divides or partitions the total requested torque between the vehicle&#39;s powertrain (i.e., engine  14  and motor  18 ) and brake assemblies  38  and issues corresponding commands to the engine controller  50 , transaxle controller  48  and brake controller  52 .  
     [0030] Battery management control portion  60  interfaces with the battery controller  46  and controls the opening and closing of the contactors in the battery pack  36 , based upon the vehicle mode signals received from portion  56 . Portion  60  also reads and processes discharge/charge power limits from the battery controller  46 , monitors the battery  36  for faults and communicates this information to the other VSC  40  control portions  56 ,  58 , and  62   70 .  
     [0031] Driver information control portion  62  receives signals from the vehicle sensors  44  and controllers  46 - 52  and calculates vehicle operating data that is conveyed to the driver. Particularly, portion  62  receives measured data from sensors  44 , calculates values for vehicle operating conditions (e.g., vehicle speed, battery state of charge, available battery power, and other values) by use of conventional algorithms, and communicates signals representing these values to the instrument panel or cluster  54 , and to other vehicle displays or data providing devices.  
     [0032] Energy management control portion  64  controls the power flow between the engine  14 , motor  18 , generator  16 , battery  36 , and the wheels. Portion  64  aims to meet the driver needs of power, security and climate control, the program requirements of meeting or exceeding fuel economy, emissions, performance and driveability targets and component requirements such as the maintenance of the battery state of charge within a certain range. The above requirements are met within the constraints imposed by the various components, such as the battery  36 , the transaxle, the regenerative braking system, the engine  14 , the cooling system, the fuel system and the exhaust system. Portion  64  also processes system faults and based on the LOS mode, portion  64  takes appropriate action to modify the powertrain operating mode (e.g., electric versus hybrid) and the operating point (e.g., desired engine torque and speed).  
     [0033] Brake system control portion  66  implements the regenerative braking control process of the VSC  40  (whether it be for series regenerative braking or for parallel regenerative braking). Portion  66  may also control the components (i.e., engine  14 , output shaft  32 , planetary gear set  20 , and drive train  28 ) to utilize engine compression braking when regenerative braking is not available.  
     [0034] Engine start/stop control portion  68  coordinates the timing and operation of the “startup” and “shutdown” of the vehicle&#39;s engine  14 . Portion  68  contains the logical condition used to decide whether to turn on/off the engine  14  or, if already “on”, whether to keep engine  14  “running”. Portion  68  also coordinates the process of engine startup among the engine controller  50  and the transaxle controller  48  in order to minimize undesirable noise, vibrations, “harshness”, and emissions.  
     [0035] Torque estimation control portion  70  estimates the torque produced by the engine  14  and the transaxle (i.e., motor  18  and generator  16 ). Portion  70  receives torque estimates from the engine controller  50  and transaxle controller  48 , and compares the engine controller  50  estimate to the transaxle controller  48  estimate to ensure these estimates are similar. If the estimates vary beyond a certain threshold value, portion  70  notifies portion  56  of a potential fault condition.  
     [0036] In operation, VSC  40  receives commands from driver controls  42 , signals from sensors  44  and feedback from controllers  46 - 52 . Particularly, controller  40  receives signals and/or commands generated by driver inputs, vehicle operating condition sensors (e.g., gear selection, accelerator position, and braking effort), and subsystem controllers (i.e., feedback) and processes and utilizes the received signals to determine the amount of torque which is to be provided to the vehicle&#39;s drive train  28  and to generate commands to the appropriate subsystems or controllers  46 - 52  which selectively provide the desired torque to the drive train  28  and to provide the requisite functionality to vehicle  10 . Each portion  56 - 70  of the VSC  40  performs a unique vehicle function as set forth above. This unique arrangement allows for the vehicle components and processes to be easily switched or replaced, without requiring a reprogramming or replacement of the entire controller. This allows modifications to vehicle  10  to be performed relatively quickly, and also allows this VSC  40  to be used on various types of vehicles with portions  56 - 70  being selected and/or adjusted based upon the particular vehicle&#39;s functionality.  
     [0037] It is understood that the invention is not limited by the exact construction or method illustrated and described above, but that various changes and/or modifications may be made without departing from the spirit and/or the scope of the inventions.