Patent Publication Number: US-8118903-B2

Title: Method for preferential selection of modes and gear with inertia effects for a hybrid powertrain system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/985,271 filed on Nov. 4, 2007 which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure pertains to control systems for hybrid powertrain systems. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Known hybrid powertrain architectures include torque-generative devices, including internal combustion engines and electric machines, which transfer torque through a transmission device to an output member. One exemplary hybrid powertrain includes a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving tractive torque from a prime mover power source, preferably an internal combustion engine, and an output member. The output member can be operatively connected to a driveline for a motor vehicle for transferring tractive torque thereto. Electric machines, operative as motors or generators, generate a torque input to the transmission, independently of a torque input from the internal combustion engine. The electric machines may transform vehicle kinetic energy, transferred through the vehicle driveline, to electrical energy that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange among the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed. 
     SUMMARY 
     A method for controlling a hybrid powertrain system selectively operative in one of a plurality of operating range states including an engine includes monitoring an operator torque request and a rotational speed of the output member, determining inertial effects of the transmissions, determining motor torque outputs from the electrical machines and an engine based upon the inertial effects, and selecting a preferred operating range state and a preferred input speed from the engine to the transmission based upon the operator torque request and the inertial effects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of an exemplary powertrain, in accordance with the present disclosure; 
         FIG. 2  is a schematic diagram of an exemplary architecture for a control system and powertrain, in accordance with the present disclosure; 
         FIG. 3  illustrates a control system architecture for controlling and managing torque in a hybrid powertrain system, in accordance with the present disclosure; 
         FIG. 4  is a schematic flow diagram illustrating the strategic optimization control scheme, in accordance with the present disclosure; 
         FIG. 5  is a schematic flow diagram illustrating several aspects of a strategic manager, in accordance with the present disclosure; 
         FIG. 6  is a schematic flow diagram illustrating the strategic optimization scheme, in accordance with the present disclosure; 
         FIGS. 7-9  are schematic flow diagrams, in accordance with the present disclosure; and 
         FIG. 10  is a datagraph, in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein the showings are for the purpose of illustrating certain exemplary embodiments only and not for the purpose of limiting the same,  FIGS. 1 and 2  depict an exemplary electro-mechanical hybrid powertrain system. The exemplary electro-mechanical hybrid powertrain system in accordance with the present disclosure is depicted in  FIG. 1 , comprising a two-mode, compound-split, electro-mechanical hybrid transmission  10  operatively connected to an engine  14  and torque generating machines comprising first and second electric machines (‘MG-A’)  56  and (‘MG-B’)  72 . The engine  14  and first and second electric machines  56  and  72  each generate mechanical power which can be transferred to the transmission  10 . The power generated by the engine  14  and the first and second electric machines  56  and  72  and transferred to the transmission  10  is described in terms of input and motor torques, referred to herein as T I , T A , and T B  respectively, and speed, referred to herein as N I , N A , and N B , respectively. 
     The exemplary engine  14  comprises a multi-cylinder internal combustion engine selectively operative in several states to transfer torque to the transmission  10  via an input shaft  12 , and can be either a spark-ignition or a compression-ignition engine. The engine  14  includes a crankshaft (not shown) operatively coupled to the input shaft  12  of the transmission  10 . A rotational speed sensor  11  monitors rotational speed of the input shaft  12 . Power output from the engine  14 , comprising rotational speed and engine torque, can differ from the input speed N I  and the input torque T I  to the transmission  10  due to placement of torque-consuming components on the input shaft  12  between the engine  14  and the transmission  10 , e.g., a hydraulic pump (not shown) and/or a torque management device (not shown). 
     The exemplary transmission  10  comprises three planetary-gear sets  24 ,  26  and  28 , and four selectively engageable torque-transferring devices, i.e., clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75 . As used herein, clutches refer to any type of friction torque transfer device including single or compound plate clutches or packs, band clutches, and brakes, for example. A hydraulic control circuit  42 , preferably controlled by a transmission control module (hereafter ‘TCM’)  17 , is operative to control clutch states. Clutches C 2   62  and C 4   75  preferably comprise hydraulically-applied rotating friction clutches. Clutches C 1   70  and C 3   73  preferably comprise hydraulically-controlled stationary devices that can be selectively grounded to a transmission case  68 . Each of the clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75  is preferably hydraulically applied, selectively receiving pressurized hydraulic fluid via the hydraulic control circuit  42 . 
     The first and second electric machines  56  and  72  preferably comprise three-phase AC machines, each including a stator (not shown) and a rotor (not shown), and respective resolvers  80  and  82 . The motor stator for each machine is grounded to an outer portion of the transmission case  68 , and includes a stator core with coiled electrical windings extending therefrom. The rotor for the first electric machine  56  is supported on a hub plate gear that is operatively attached to shaft  60  via the second planetary gear set  26 . The rotor for the second electric machine  72  is fixedly attached to a sleeve shaft hub  66 . 
     Each of the resolvers  80  and  82  preferably comprises a variable reluctance device including a resolver stator (not shown) and a resolver rotor (not shown). The resolvers  80  and  82  are appropriately positioned and assembled on respective ones of the first and second electric machines  56  and  72 . Stators of respective ones of the resolvers  80  and  82  are operatively connected to one of the stators for the first and second electric machines  56  and  72 . The resolver rotors are operatively connected to the rotor for the corresponding first and second electric machines  56  and  72 . Each of the resolvers  80  and  82  is signally and operatively connected to a transmission power inverter control module (hereafter ‘TPIM’)  19 , and each senses and monitors rotational position of the resolver rotor relative to the resolver stator, thus monitoring rotational position of respective ones of first and second electric machines  56  and  72 . Additionally, the signals output from the resolvers  80  and  82  are interpreted to provide the rotational speeds for first and second electric machines  56  and  72 , i.e., N A  and N B , respectively. 
     The transmission  10  includes an output member  64 , e.g. a shaft, which is operably connected to a driveline  90  for a vehicle (not shown), to provide output power to the driveline  90  that is transferred to vehicle wheels  93 , one of which is shown in  FIG. 1 . The output power at the output member  64  is characterized in terms of an output rotational speed N O  and an output torque T O . A transmission output speed sensor  84  monitors rotational speed and rotational direction of the output member  64 . Each of the vehicle wheels  93  is preferably equipped with a friction brake  94  and a sensor (not shown) adapted to monitor wheel speed, the output of which is monitored by a control module of a distributed control module system described with respect to  FIG. 2 , to determine vehicle speed, and absolute and relative wheel speeds for braking control, traction control, and vehicle acceleration management. 
     The input torque from the engine  14  and the motor torques from the first and second electric machines  56  and  72  (T I , T A , and T B  respectively) are generated as a result of energy conversion from fuel or electrical potential stored in an electrical energy storage device (hereafter ‘ESD’)  74 . The ESD  74  is high voltage DC-coupled to the TPIM  19  via DC transfer conductors  27 . The transfer conductors  27  include a contactor switch  38 . When the contactor switch  38  is closed, under normal operation, electric current can flow between the ESD  74  and the TPIM  19 . When the contactor switch  38  is opened electric current flow between the ESD  74  and the TPIM  19  is interrupted. The TPIM  19  transmits electrical power to and from the first electric machine  56  by transfer conductors  29 , and the TPIM  19  similarly transmits electrical power to and from the second electric machine  72  by transfer conductors  31  to meet the torque commands for the first and second electric machines  56  and  72  in response to the motor torque commands T A  and T B . Electrical current is transmitted to and from the ESD  74  in accordance with whether the ESD  74  is being charged or discharged. 
     The TPIM  19  includes the pair of power inverters (not shown) and respective motor control modules (not shown) configured to receive the motor torque commands and control inverter states therefrom for providing motor drive or regeneration functionality to meet the commanded motor torques T A  and T B . The power inverters comprise known complementary three-phase power electronics devices, and each includes a plurality of insulated gate bipolar transistors (not shown) for converting DC power from the ESD  74  to AC power for powering respective ones of the first and second electric machines  56  and  72 , by switching at high frequencies. The insulated gate bipolar transistors form a switch mode power supply configured to receive control commands. There is typically one pair of insulated gate bipolar transistors for each phase of each of the three-phase electric machines. States of the insulated gate bipolar transistors are controlled to provide motor drive mechanical power generation or electric power regeneration functionality. The three-phase inverters receive or supply DC electric power via DC transfer conductors  27  and transform it to or from three-phase AC power, which is conducted to or from the first and second electric machines  56  and  72  for operation as motors or generators via transfer conductors  29  and  31  respectively. 
       FIG. 2  is a schematic block diagram of the distributed control module system. The elements described hereinafter comprise a subset of an overall vehicle control architecture, and provide coordinated system control of the exemplary hybrid powertrain described in  FIG. 1 . The distributed control module system synthesizes pertinent information and inputs, and executes algorithms to control various actuators to meet control objectives, including objectives related to fuel economy, emissions, performance, drivability, and protection of hardware, including batteries of ESD  74  and the first and second electric machines  56  and  72 . The distributed control module system includes an engine control module (hereafter ‘ECM’)  23 , the TCM  17 , a battery pack control module (hereafter ‘BPCM’)  21 , and the TPIM  19 . A hybrid control module (hereafter ‘HCP’)  5  provides supervisory control and coordination of the ECM  23 , the TCM  17 , the BPCM  21 , and the TPIM  19 . A user interface (‘UI’)  13  is operatively connected to a plurality of devices through which a vehicle operator controls or directs operation of the electro-mechanical hybrid powertrain system. The devices include an accelerator pedal  113  (‘AP’), an operator brake pedal  112  (‘BP’), a transmission gear selector  114  (‘PRNDL’), and a vehicle speed cruise control (not shown). The transmission gear selector  114  may have a discrete number of operator-selectable positions, including the rotational direction of the output member  64  to enable one of a forward and a reverse direction. 
     The aforementioned control modules communicate with other control modules, sensors, and actuators via a local area network (hereafter ‘LAN’) bus  6 . The LAN bus  6  allows for structured communication of states of operating parameters and actuator command signals between the various control modules. The specific communication protocol utilized is application-specific. The LAN bus  6  and appropriate protocols provide for robust messaging and multi-control module interfacing between the aforementioned control modules, and other control modules providing functionality including e.g., antilock braking, traction control, and vehicle stability. Multiple communications buses may be used to improve communications speed and provide some level of signal redundancy and integrity. Communication between individual control modules can also be effected using a direct link, e.g., a serial peripheral interface (‘SPI’) bus (not shown). 
     The HCP  5  provides supervisory control of the hybrid powertrain, serving to coordinate operation of the ECM  23 , TCM  17 , TPIM  19 , and BPCM  21 . Based upon various input signals from the user interface  13  and the hybrid powertrain, including the ESD  74 , the HCP  5  determines an operator torque request, an output torque command, an engine input torque command, clutch torque(s) for the applied torque-transfer clutches C 1   70 , C 2   62 , C 3   73 , C 4   75  of the transmission  10 , and the motor torque commands T A  and T B  for the first and second electric machines  56  and  72 . 
     The ECM  23  is operatively connected to the engine  14 , and functions to acquire data from sensors and control actuators of the engine  14  over a plurality of discrete lines, shown for simplicity as an aggregate bi-directional interface cable  35 . The ECM  23  receives the engine input torque command from the HCP  5 . The ECM  23  determines the actual engine input torque, T I , provided to the transmission  10  at that point in time based upon monitored engine speed and load, which is communicated to the HCP  5 . The ECM  23  monitors input from the rotational speed sensor  11  to determine the engine input speed to the input shaft  12 , which translates to the transmission input speed, N I . The ECM  23  monitors inputs from sensors (not shown) to determine states of other engine operating parameters including, e.g., a manifold pressure, engine coolant temperature, ambient air temperature, and ambient pressure. The engine load can be determined, for example, from the manifold pressure, or alternatively, from monitoring operator input to the accelerator pedal  113 . The ECM  23  generates and communicates command signals to control engine actuators, including, e.g., fuel injectors, ignition modules, and throttle control modules, none of which are shown. 
     The TCM  17  is operatively connected to the transmission  10  and monitors inputs from sensors (not shown) to determine states of transmission operating parameters. The TCM  17  generates and communicates command signals to control the transmission  10 , including controlling the hydraulic circuit  42 . Inputs from the TCM  17  to the HCP  5  include estimated clutch torques for each of the clutches, i.e., C 1   70 , C 2   62 , C 3   73 , and C 4   75 , and rotational output speed, N O , of the output member  64 . Other actuators and sensors may be used to provide additional information from the TCM  17  to the HCP  5  for control purposes. The TCM  17  monitors inputs from pressure switches (not shown) and selectively actuates pressure control solenoids (not shown) and shift solenoids (not shown) of the hydraulic circuit  42  to selectively actuate the various clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75  to achieve various transmission operating range states, as described hereinbelow. 
     The BPCM  21  is signally connected to sensors (not shown) to monitor the ESD  74 , including states of electrical current and voltage parameters, to provide information indicative of parametric states of the batteries of the ESD  74  to the HCP  5 . The parametric states of the batteries preferably include battery state-of-charge, battery voltage, battery temperature, and available battery power, referred to as a range P BAT     —     MIN  to P BAT     —     MAX . 
     A brake control module (hereafter ‘BrCM’)  22  is operatively connected to friction brakes  94  on each of the vehicle wheels  93 . The BrCM  22  monitors the operator input to the brake pedal  112  and generates control signals to control the friction brakes  94  and sends a control signal to the HCP  5  to operate the first and second electric machines  56  and  72  based thereon. 
     Each of the control modules ECM  23 , TCM  17 , TPIM  19 , BPCM  21 , and BrCM  22  is preferably a general-purpose digital computer comprising a microprocessor or central processing unit, storage mediums comprising read only memory (‘ROM’), random access memory (‘RAM’), electrically programmable read only memory (‘EPROM’), a high speed clock, analog to digital (‘A/D’) and digital to analog (‘D/A’) circuitry, and input/output circuitry and devices (‘I/O’) and appropriate signal conditioning and buffer circuitry. Each of the control modules has a set of control algorithms, comprising resident program instructions and calibrations stored in one of the storage mediums and executed to provide the respective functions of each computer. Information transfer between the control modules is preferably accomplished using the LAN bus  6  and serial peripheral interface buses. The control algorithms are executed during preset loop cycles such that each algorithm is executed at least once each loop cycle. Algorithms stored in the non-volatile memory devices are executed by one of the central processing units to monitor inputs from the sensing devices and execute control and diagnostic routines to control operation of the actuators, using preset calibrations. Loop cycles are executed at regular intervals, for example each 3.125, 6.25, 12.5, 25 and 100 milliseconds during ongoing operation of the hybrid powertrain. Alternatively, algorithms may be executed in response to the occurrence of an event. 
     The exemplary hybrid powertrain selectively operates in one of several states that can be described in terms of engine states comprising one of an engine-on state (‘ON’) and an engine-off state (‘OFF’), and transmission operating range states comprising a plurality of fixed gears and continuously variable operating modes, described with reference to Table 1, below. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Engine 
                 Transmission Operating 
                 Applied 
               
               
                 Description 
                 State 
                 Range State 
                 Clutches 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 M1_Eng_Off 
                 OFF 
                 EVT Mode 1 
                 C1 70 
                   
               
               
                 M1_Eng_On 
                 ON 
                 EVT Mode 1 
                 C1 70 
               
               
                 G1 
                 ON 
                 Fixed Gear Ratio 1 
                 C1 70 
                 C4 75 
               
               
                 G2 
                 ON 
                 Fixed Gear Ratio 2 
                 C1 70 
                 C2 62 
               
               
                 M2_Eng_Off 
                 OFF 
                 EVT Mode 2 
                 C2 62 
               
               
                 M2_Eng_On 
                 ON 
                 EVT Mode 2 
                 C2 62 
               
               
                 G3 
                 ON 
                 Fixed Gear Ratio 3 
                 C2 62 
                 C4 75 
               
               
                 G4 
                 ON 
                 Fixed Gear Ratio 4 
                 C2 62 
                 C3 73 
               
               
                   
               
            
           
         
       
     
     Each of the transmission operating range states is described in the table and indicates which of the specific clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75  are applied for each of the operating range states. A first continuously variable mode, i.e., EVT Mode  1 , or M 1 , is selected by applying clutch C 1   70  only in order to “ground” the outer gear member of the third planetary gear set  28 . The engine state can be one of ON (‘M 1 _Eng_On’) or OFF (‘M 1 _Eng_Off’). A second continuously variable mode, i.e., EVT Mode  2 , or M 2 , is selected by applying clutch C 2   62  only to connect the shaft  60  to the carrier of the third planetary gear set  28 . The engine state can be one of ON (‘M 2 _Eng_On’) or OFF (‘M 2 _Eng_Off’). For purposes of this description, when the engine state is OFF, the engine input speed is equal to zero revolutions per minute (‘RPM’), i.e., the engine crankshaft is not rotating. A fixed gear operation provides a fixed ratio operation of input-to-output speed of the transmission  10 , i.e., N I /N O . A first fixed gear operation (‘G 1 ’) is selected by applying clutches C 1   70  and C 4   75 . A second fixed gear operation (‘G 2 ’) is selected by applying clutches C 1   70  and C 2   62 . A third fixed gear operation (‘G 3 ’) is selected by applying clutches C 2   62  and C 4   75 . A fourth fixed gear operation (‘G 4 ’) is selected by applying clutches C 2   62  and C 3   73 . The fixed ratio operation of input-to-output speed increases with increased fixed gear operation due to decreased gear ratios in the planetary gears  24 ,  26 , and  28 . The rotational speeds of the first and second electric machines  56  and  72 , N A  and N B  respectively, are dependent on internal rotation of the mechanism as defined by the clutching and are proportional to the input speed measured at the input shaft  12 . 
     In response to operator input via the accelerator pedal  113  and brake pedal  112  as captured by the user interface  13 , the HCP  5  and one or more of the other control modules determine torque commands to control the torque generative devices comprising the engine  14  and the first and second electric machines  56  and  72  to meet the operator torque request at the output member  64  and transferred to the driveline  90 . Based upon input signals from the user interface  13  and the hybrid powertrain including the ESD  74 , the HCP  5  determines the operator torque request, a commanded output torque from the transmission  10  to the driveline  90 , the input torque from the engine  14 , clutch torques for the torque-transfer clutches C 1   70 , C 2   62 , C 3   73 , C 4   75  of the transmission  10 ; and the motor torques for the first and second electric machines  56  and  72 , respectively, as is described hereinbelow. 
     Final vehicle acceleration can be affected by other factors including, e.g., road load, road grade, and vehicle mass. The engine state and the transmission operating range state are determined based upon operating characteristics of the hybrid powertrain. This includes the operator torque request communicated through the accelerator pedal  113  and brake pedal  112  to the user interface  13  as previously described. The transmission operating range state and the engine state may be predicated on a hybrid powertrain torque demand caused by a command to operate the first and second electric machines  56  and  72  in an electrical energy generating mode or in a torque generating mode. The transmission operating range state and the engine state can be determined by an optimization algorithm or routine which determines optimum system efficiency based upon operator demand for power, battery state of charge, and energy efficiencies of the engine  14  and the first and second electric machines  56  and  72 . The control system manages torque inputs from the engine  14  and the first and second electric machines  56  and  72  based upon an outcome of the executed optimization routine, and system efficiencies are optimized thereby, to manage fuel economy and battery charging. Furthermore, operation can be determined based upon a fault in a component or system. The HCP  5  monitors the torque-generative devices, and determines the power output from the transmission  10  at output member  64  that is required to meet the operator torque request while meeting other powertrain operating demands, e.g., charging the ESD  74 . As should be apparent from the description above, the ESD  74  and the first and second electric machines  56  and  72  are electrically-operatively coupled for power flow therebetween. Furthermore, the engine  14 , the first and second electric machines  56  and  72 , and the electro-mechanical transmission  10  are mechanically-operatively coupled to transfer power therebetween to generate a power flow to the output member  64 . 
       FIG. 3  shows a control system architecture for controlling and managing signal flow in a hybrid powertrain system having multiple torque generative devices, described hereinbelow with reference to the hybrid powertrain system of  FIGS. 1 and 2 , and residing in the aforementioned control modules in the form of executable algorithms and calibrations. The control system architecture is applicable to alternative hybrid powertrain systems having multiple torque generative devices, including, e.g., a hybrid powertrain system having an engine and a single electric machine, a hybrid powertrain system having an engine and multiple electric machines. Alternatively, the hybrid powertrain system can utilize non-electric torque-generative machines and energy storage systems, e.g., hydraulic-mechanical hybrid transmissions (not shown). 
     In operation, the operator inputs to the accelerator pedal  113  and the brake pedal  112  are monitored to determine the operator torque request. The operator inputs to the accelerator pedal  113  and the brake pedal  112  comprise individually determinable operator torque request inputs including an immediate accelerator output torque request (‘Output Torque Request Accel Immed’), a predicted accelerator output torque request (‘Output Torque Request Accel Prdtd’), an immediate brake output torque request (‘Output Torque Request Brake Immed’), a predicted brake output torque request (‘Output Torque Request Brake Prdtd’) and an axle torque response type (‘Axle Torque Response Type’). As used herein, the term ‘accelerator’ refers to an operator request for forward propulsion preferably resulting in increasing vehicle speed over the present vehicle speed, when the operator selected position of the transmission gear selector  114  commands operation of the vehicle in the forward direction. The terms ‘deceleration’ and ‘brake’ refer to an operator request preferably resulting in decreasing vehicle speed from the present vehicle speed. The immediate accelerator output torque request, the predicted accelerator output torque request, the immediate brake output torque request, the predicted brake output torque request, and the axle torque response type are individual inputs to the control system. Additionally, operation of the engine  14  and the transmission  10  are monitored to determine the input speed (‘Ni’) and the output speed (‘No’). The immediate accelerator output torque request is determined based upon a presently occurring operator input to the accelerator pedal  113 , and comprises a request to generate an immediate output torque at the output member  64  preferably to accelerate the vehicle. The predicted accelerator output torque request is determined based upon the operator input to the accelerator pedal  113  and comprises an optimum or preferred output torque at the output member  64 . The predicted accelerator output torque request is preferably equal to the immediate accelerator output torque request during normal operating conditions, e.g., when any one of antilock braking, traction control, or vehicle stability is not being commanded. When any one of antilock braking, traction control or vehicle stability is being commanded the predicted accelerator output torque request remains the preferred output torque with the immediate accelerator output torque request being decreased in response to output torque commands related to the antilock braking, traction control, or vehicle stability control. 
     The immediate brake output torque request is determined based upon a presently occurring operator input to the brake pedal  112 , and comprises a request to generate an immediate output torque at the output member  64  to effect a reactive torque with the driveline  90  which preferably decelerates the vehicle. The predicted brake output torque request comprises an optimum or preferred brake output torque at the output member  64  in response to an operator input to the brake pedal  112  subject to a maximum brake output torque generated at the output member  64  allowable regardless of the operator input to the brake pedal  112 . In one embodiment the maximum brake output torque generated at the output member  64  is limited to −0.2 g. The predicted brake output torque request can be phased out to zero when vehicle speed approaches zero regardless of the operator input to the brake pedal  112 . When commanded by the operator, there can be operating conditions under which the predicted brake output torque request is set to zero, e.g., when the operator setting to the transmission gear selector  114  is set to a reverse gear, and when a transfer case (not shown) is set to a four-wheel drive low range. 
     A strategic control scheme (‘Strategic Control’)  310  determines a preferred input speed (‘Ni_Des’) and a preferred engine state and transmission operating range state (‘Hybrid Range State Des’) based upon the output speed and the operator torque request and based upon other operating parameters of the hybrid powertrain, including battery power limits and response limits of the engine  14 , the transmission  10 , and the first and second electric machines  56  and  72 . The predicted accelerator output torque request and the predicted brake output torque request are input to the strategic control scheme  310 . The strategic control scheme  310  is preferably executed by the HCP  5  during each 100 ms loop cycle and each 25 ms loop cycle. The desired operating range state for the transmission  10  and the desired input speed from the engine  14  to the transmission  10  are inputs to the shift execution and engine start/stop control scheme  320 . 
     The shift execution and engine start/stop control scheme  320  commands changes in the transmission operation (‘Transmission Commands’) including changing the operating range state based upon the inputs and operation of the powertrain system. This includes commanding execution of a change in the transmission operating range state if the preferred operating range state is different from the present operating range state by commanding changes in application of one or more of the clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75  and other transmission commands. The present operating range state (‘Hybrid Range State Actual’) and an input speed profile (‘Ni_Prof’) can be determined. The input speed profile is an estimate of an upcoming input speed and preferably comprises a scalar parametric value that is a targeted input speed for the forthcoming loop cycle. The engine operating commands and the operator torque request are based upon the input speed profile during a transition in the operating range state of the transmission. 
     A tactical control scheme (‘Tactical Control and Operation’)  330  is executed during one of the control loop cycles to determine engine commands (‘Engine Commands’) for operating the engine  14 , including a preferred input torque from the engine  14  to the transmission  10  based upon the output speed, the input speed, and the operator torque request comprising the immediate accelerator output torque request, the predicted accelerator output torque request, the immediate brake output torque request, the predicted brake output torque request, the axle torque response type, and the present operating range state for the transmission. The engine commands also include engine states including one of an all-cylinder operating state and a cylinder deactivation operating state wherein a portion of the engine cylinders are deactivated and unfueled, and engine states including one of a fueled state and a fuel cutoff state. An engine command comprising the preferred input torque of the engine  14  and the present input torque (‘Ti’) reacting between the engine  14  and the input member  12  are preferably determined in the ECM  23 . Clutch torques (‘Tcl’) for each of the clutches C 1   70 , C 2   62 , C 3   73 , and C 4   75 , including the presently applied clutches and the non-applied clutches are estimated, preferably in the TCM  17 . 
     An output and motor torque determination scheme (‘Output and Motor Torque Determination’)  340  is executed to determine the preferred output torque from the powertrain (‘To_cmd’). This includes determining motor torque commands (‘T A ’, ‘T B ’) to transfer a net commanded output torque to the output member  64  of the transmission  10  that meets the operator torque request, by controlling the first and second electric machines  56  and  72  in this embodiment. The immediate accelerator output torque request, the immediate brake output torque request, the present input torque from the engine  14  and the estimated applied clutch torque(s), the present operating range state of the transmission  10 , the input speed, the input speed profile, and the axle torque response type are inputs. The output and motor torque determination scheme  340  executes to determine the motor torque commands during each iteration of one of the loop cycles. The output and motor torque determination scheme  340  includes algorithmic code which is regularly executed during the 6.25 ms and 12.5 ms loop cycles to determine the preferred motor torque commands. 
     The hybrid powertrain is controlled to transfer the output torque to the output member  64  to react with the driveline  90  to generate tractive torque at wheel(s)  93  to forwardly propel the vehicle in response to the operator input to the accelerator pedal  113  when the operator selected position of the transmission gear selector  114  commands operation of the vehicle in the forward direction. Similarly, the hybrid powertrain is controlled to transfer the output torque to the output member  64  to react with the driveline  90  to generate tractive torque at wheel(s)  93  to propel the vehicle in a reverse direction in response to the operator input to the accelerator pedal  113  when the operator selected position of the transmission gear selector  114  commands operation of the vehicle in the reverse direction. Preferably, propelling the vehicle results in vehicle acceleration so long as the output torque is sufficient to overcome external loads on the vehicle, e.g., due to road grade, aerodynamic loads, and other loads. 
     For the continuously variable modes, i.e., M 1  or M 2 , the speed relationship between first and second electric machines  56  and  72 , the input speed N I  and the output speed N O  is defined as shown in the equation below: 
                     [           N   A               N   B           ]     =       [     A   1     ]     ⁡     [           N   I               N   O           ]               [   1   ]               
wherein N I  comprises the input speed from the engine  14 , N O  is the transmission output speed, N A  and N B  are the operating speeds for first and second electric machines  56  and  72 , and A 1  is a 2×2 matrix of parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state, i.e., M 1  or M 2 .
 
     The torque relationship between first and second electric machines  56  and  72 , the input speed N I , the output speed N O , input torque, and motor torque is defined as: 
                     [           T   A               T   B           ]     =         [           a   11           a   12               a   21           a   22           ]     ⁡     [           T   I               T   O           ]       +       [           b   11           b   12               b   21           b   22           ]     ⁡     [           N   I               N   O           ]                 [   2   ]               
wherein T I  is the input torque from the engine  14 , T O  is the transmission output torque, T A  and T B  are the motor torques for first and second electric machines  56  and  72  and a 11 , a 12 , a 21 , a 22 , b 11 , b 12 , b 21 , and b 22  are scalar values of known parametric values based upon hardware gear and shaft interconnections determined for the specific application and for the specific continuously variable operating range state, i.e., M 1  or M 2 .
 
     For the fixed gear operating range states, i.e., G 1 , G 2 , G 3  and G 4  in one embodiment, the speed relationship between the first and second electric machines  56  and  72 , the engine input speed N I  and the transmission output speed N O  is defined as shown in the equation below: 
                     [           N   I               N   A               N   B           ]     =       [     B   1     ]     *     N   O               [   3   ]               
wherein N I  comprises the input speed from engine  14 , N O  is the transmission output speed, N A  and N B  are the operating speeds for first and second electric machines  56  and  72 , and B I  is a 1×3 matrix of known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state. In this application, when the transmission output speed, N O  is known, N I  for the engine  14  and N A  and N B  can be determined.
 
     The torque relationships between first and second electric machines  56  and  72 , input torque, and motor torque are as defined in Eq. 4 below: 
                     T   O     =       [         a       b       c       d       e         ]     *     [           T   I               T   A               T   B               N   i               N   o           ]               [   4   ]               
wherein T I  is the input torque from engine  14 , T O  is the transmission output torque, i.e., the requested output torque, T O     —     REQ , T A  and T B  are the motor torques for first and second electric machines  56  and  72 , a, b, c, d, and e are known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific fixed gear operating ranges state.
 
     The torque relationships given in Eqs. 2 and 4 do not compensate for inertial effects within the hybrid powertrain. To compensate for the inertial effects, the rotational acceleration of the input member  12  and the output member  56  are included in Eq. 2 for the mode operating range states. Including the rotational acceleration terms the torque relationship between first and second electric machines  56  and  72 , the input speed N I , the output speed N O , the input torque, and motor torques T A  and T B  is defined as: 
                     [           T   A               T   B           ]     =         [           a   11           a   12               a   21           a   22           ]     ⁡     [           T   I               T   O           ]       +       [           b   11           b   12               b   21           b   22           ]     ⁡     [           N   I               N   O           ]       +       [           c   11           c   12               c   21           c   22           ]     ⁢       [           N   I                 N   .     O           ]     .                 [   5   ]               
wherein
         {dot over (N)} I  represents acceleration of the input member  12 ,   {dot over (N)} O  represents acceleration of output member  64 , and   a 11 , a 12 , a 21 , a 22 , b 11 , b 12 , b 21 , b 22  c 11 , c 12 , c 21 , and c 22  are known parametric values based upon hardware gear and shaft interconnections determined for the specific application and for the specific operating range state, i.e., M 1  or M 2 .       

     For the fixed gear operating ranges states, compensating for the inertial effects comprises including the rotational acceleration of the input member  12  in Eq. 4. Including the rotational acceleration of the input member  12  the torque relationships between first and second electric machines  56  and  72 , input torque, and output torque are defined as: 
                     T   O     =       [         a       b       c       d       e       f         ]     *     [           T   I               T   A               T   B               N   i               N   o                 N   .     I           ]               [   6   ]               
wherein {dot over (N)} I  represents acceleration of the input member  12 , and a, b, c, d, e, and f are known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state.
 
       FIG. 4  details signal flow in the strategic optimization control scheme  310 , which includes a strategic manager  220 , an operating range state analyzer  260 , and a state stabilization and arbitration block  280  to determine the preferred input speed (‘Ni_Des’) and the preferred transmission operating range state (‘Hybrid Range State Des’). The strategic manager (‘Strategic Manager’)  220  monitors the output speed N O , the predicted accelerator output torque request (‘Output Torque Request Accel Prdtd’), the predicted brake output torque request (‘Output Torque Request Brake Prdtd’), and available battery power P BAT     —     MIN  to P BAT     —     MAX . The strategic manager  220  determines which of the transmission operating range states are allowable, and determines output torque requests comprising a strategic accelerator output torque request (‘Output Torque Request Accel Strategic’) and a strategic net output torque request (‘Output Torque Request Net Strategic’), all of which are input the operating range state analyzer  260  along with system inputs (‘System Inputs’) and power cost inputs (‘Power Cost Inputs’). The operating range state analyzer  260  generates a preferred power cost (‘P*cost’) and associated input speed (‘N*i’) for each of the allowable operating range states based upon the operator torque requests, the system inputs, the available battery power and the power cost inputs. The preferred power costs and associated input speeds for the allowable operating range states are input to the state stabilization and arbitration block  280  which selects the preferred operating range state and preferred input speed based thereon. 
       FIG. 5  shows a functional block diagram detailing an operation of the strategic manager  220 . Within the strategic manager  220  are an input acceleration algorithm (‘Calc Nidot (Modes)’) ( 221 ), a torque offset algorithm (‘Precalc TrqOffsets’) ( 222 ), and a strategic manager algorithm ( 223 ). Inputs to the strategic manager algorithm include the predicted accelerator output torque request (‘Output Torque Request Accel Prdtd’), the predicted brake output torque request (‘Output Torque Request Brake Prdtd’), and the output speed (‘N O ’). The strategic manager algorithm  223  determines a strategic output speed, the strategic torque request, and a rotational output acceleration of the output member  64 . The input acceleration algorithm  221  inputs the strategic output speed (‘No Strategic’), the strategic torque request (‘To Req Strategic’), and the rotational output acceleration (‘Nodot’). The input acceleration algorithm  221  determines a rotational input acceleration (‘Nidot’) of the input member  12  for the continuously variable modes M 1  and M 2 . The torque offset algorithm  222  determines a torque offset for each of the first and second electrical machines  56  and  72  (‘Ta offset’ and ‘Tb offset’) for operating in one of the continuously variable modes and an output torque offset for the operating in one of the fixed gears (‘To offset’). The torque offsets are preferably determined in the strategic manager  220  for increased computational efficiency. The torque offsets are output to the operating range state analyzer  260  as described hereinbelow. 
     Preferably, the strategic output speed comprises a predicted output speed occurring at a future time instant. One method for determining the predicted output speed comprises determining a time-based derivative of the monitored output speed No, multiplying the resultant with an elapsed time from the present to the future time instant and adding the resultant to the monitored output speed No. The strategic torque request is preferably a predicted operator torque request for a future time instant and is preferably based upon the predicted accelerator output torque request. The rotational output acceleration is preferably determined based upon the monitored output speed. The rotational output acceleration can be determined by calculating a time-based derivative of the output speed N O  and adding the resultant to the monitored output speed No. 
     Preferably, for efficient implementation of Eq. 6 above and for the mode operating range states M 1  and M 2 , motor torque offsets are determined for each of the first and second electrical machines  56  and  72 . The motor torque offsets are determined based upon the rotational output acceleration, the rotational input acceleration, and the strategic output speed. The torque offset for the first electrical machine  56  is determined based on the following equation:
 
 T   A     —     OFFSET   =b   12   N   O   +c   11   {dot over (N)}   I   +c   12   {dot over (N)}   O   [7]
 
wherein
         N O  represents output speed,   {dot over (N)} I  represents input acceleration,   {dot over (N)} O  represents output acceleration, and   b 12 , c 11 , and c 12  represent known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state.       

     The torque offset for the second electrical machine  72  is determined based on the following equation:
 
 T   B     —     OFFSET   =b   22   N   O   +c   21   {dot over (N)}   I   +c   22   {dot over (N)}   O   [8]
 
wherein
         N O  represents output speed,   {dot over (N)} I  represents input acceleration,   {dot over (N)} O  represents output acceleration, and   b 22 , c 21 , and c 22  represent known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state.       

     Preferably, for efficient implementation of Eq. 6 above and for the fixed gear operating range states, an output torque offset is determined. The torque offset is determined based upon the rotational output acceleration, the strategic output speed, and the input speed N I . The output torque offset is determined based on the following equation:
 
 T   O Offset= dN   I   +eN   O   +f{dot over (N)}   I   [9]
 
wherein
         d, e, and f represent known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state.       

       FIG. 6  shows the operating range state analyzer  260 . The operating range state analyzer  260  executes searches in each candidate operating range state comprising the allowable ones of the operating range states, including M 1  ( 262 ), M 2  ( 264 ), G 1  ( 270 ), G 2  ( 272 ), G 3  ( 274 ), and G 4  ( 276 ) to determine preferred operation of the torque actuators, i.e., the engine  14  and the first and second electric machines  56  and  72  in this embodiment. The preferred operation preferably comprises a minimum power cost for operating the hybrid powertrain system and an associated engine input for operating in the candidate operating range state in response to the operator torque request. The associated engine input comprises at least one of a preferred engine input speed (‘Ni*’), a preferred engine input power (‘Pi*’), and a preferred engine input torque (‘Ti*’) that is responsive to and preferably meets the operator torque request. The operating range state analyzer  260  evaluates M 1 -Engine Off ( 264 ) and M 2 -Engine Off ( 266 ) to determine a preferred cost (‘P*cost’) for operating the powertrain system responsive to and preferably meeting the operator torque request when the engine  14  is in the engine-off state. 
       FIG. 7  schematically shows signal flow for the 1-dimension search scheme  610 . A range of one controllable input, in this embodiment comprising minimum and maximum input torques (‘TiMin/Max’), is input to a 1-D search engine  415 . The 1-D search engine  415  iteratively generates candidate input torques (‘Ti(j)’) which range between the minimum and maximum input torques, each which is input to an optimization function (‘Opt To/Ta/Tb’)  440 , for n search iterations. Other inputs to the optimization function  440  include system inputs preferably comprise parametric states for battery power, clutch torques, electric motor operation, transmission and engine operation, the specific operating range state and the operator torque request. The optimization function  440  determines transmission operation comprising an output torque, motor torques, and associated battery powers (‘To(j), Ta(j), Tb(j), Pbat(j), Pa(j), Pb(j)’) associated with the candidate input torque based upon the system inputs in response to the operator torque request for the candidate operating range state. 
       FIG. 8  shows the preferred operation in each of continuously variable modes M 1  and M 2  executed in blocks  262  and  264  of the operating range state analyzer  260 . This includes executing a 2-dimensional search scheme  620 , shown with reference to  FIGS. 7 and 9 , in conjunction with executing a 1-dimensional search using the 1-dimensional search scheme  610  based upon a previously determined input speed which can be arbitrated (‘Input Speed Stabilization and Arbitration’)  615  to determine preferred costs (‘P*cost’) and associated preferred input speeds (‘N*i’) for the operating range states. As described with reference to  FIG. 8 , the 2-dimensional search scheme  620  determines a a first preferred cost (‘2D P*cost’) and an associated first preferred input speed (‘2D N*I’). The first preferred input speed is input to the 2-dimensional search scheme  620  and to an adder  612 . The adder  612  sums the first preferred input speed and a time-rate change in the input speed (‘N I     —     DOT ’) multiplied by a predetermined time period (‘dt’). The resultant is input to a switch  605  along with the first preferred input speed determined by the 2-dimensional search scheme  620 . The switch  605  is controlled to input either the resultant from the adder  612  or the preferred input speed determined by the 2-dimensional search scheme  620  into the 1-dimensional search scheme  610 . The switch  605  is controlled to input the preferred input speed determined by the 2-dimensional search scheme  620  into the 1-dimensional search scheme  610  (as shown) when the powertrain system is operating in a regenerative braking mode, e.g., when the operator torque request includes a request to generate an immediate output torque at the output member  64  to effect a reactive torque with the driveline  90  which preferably decelerates the vehicle. The switch  605  is controlled to a second position (not shown) to input the resultant from the adder  612  when the operator torque request does not include regenerative braking. The 1-dimensional search scheme  610  is executed to determine a second preferred cost (‘1D P*cost’) using the 1-dimensional search scheme  610 , which is input to the input speed stabilization and arbitration block  615  to select a final preferred cost and associated preferred input speed. 
       FIG. 9  schematically shows signal flow for the 2-dimension search scheme  620 . Ranges of two controllable inputs, in this embodiment comprising minimum and maximum input speeds (‘NiMin/Max’) and minimum and maximum input powers (‘PiMin/Max’) are input to a 2-D search engine  410 . In another embodiment, the two controllable inputs can comprise minimum and maximum input speeds and minimum and maximum input torques. The 2-D search engine  410  iteratively generates candidate input speeds (‘Ni(j)’) and candidate input powers (‘Pi(j)’) which range between the minimum and maximum input speeds and powers. The candidate input power is preferably converted to a candidate input torque (‘Ti(j)’) ( 412 ). Each candidate input speed (‘Ni(j)’) and candidate input torque (‘Ti(j)’) are input to an optimization function (‘Opt To/Ta/Tb’)  440 , for n search iterations. Other inputs to the optimization function  440  include system inputs preferably comprising parametric states for battery power, clutch torques, electric motor operation, transmission and engine operation, the specific operating range state and the operator torque request. The optimization function  440  determines transmission operation comprising an output torque, motor torques, and associated battery powers (‘To(j), Ta(j), Tb(j), Pbat(j), Pa(j), Pb(j)’) associated with the candidate input power and candidate input speed based upon the system inputs and the operating torque request for the candidate operating range state. 
     Additional inputs into the optimization function  440  include the motor torque offsets and the output torque offset. For the fixed gear operating ranges states, the optimization function  440  determines the output torque for each candidate input speeds Ni(j) and candidate input torque Ti(j) based upon the output torque offset determined in the strategic manager  220 , motor torques, and known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state. The output torque can be determined based upon the following equation: 
                         T   O     ⁡     (   j   )       -       [         a       b       c         ]     ⁡     [             T   I     ⁡     (   j   )                   T   A     ⁡     (   j   )                   T   B     ⁡     (   j   )             ]       +       T   o     ⁢   Offset       ⁢                   [   10   ]               
wherein
         T A (j) represents motor torque for the first electric machine  56 ,   T B (j) represents motor torque for the second electric machine  72 ,   T I (j) represents engine input torque to the transmission  10 ,   T O (j) is the output torque out of the transmission  10 , and   a, b, and c are known parametric values based upon hardware gear and shaft interconnections determined for the specific application and for the specific operating range state.       

     For the continuously variable mode operating range states M 1  and M 2 , the optimization function  440  determines the output torque and motor torques for each candidate input speeds Ni(j) and candidate input powers Pi(j) based upon the motor torque offsets determined in the strategic manager  220 , the candidate input torque Ti(j), output torque, candidate input speed Ni(j), and known parametric values based upon hardware gear and shaft interconnections determined for the specific application, and for the specific operating range state. The output torque and motor torques are determined based upon the following equation: 
                     [             T   A     ⁡     (   j   )                   T   B     ⁡     (   j   )             ]     =         [           a   11           a   12               a   21           a   22           ]     ⁡     [             T   I     ⁡     (   j   )                   T   O     ⁡     (   j   )             ]       +       [             b   11     ·       N   I     ⁡     (   j   )                     b   21     ·       N   I     ⁡     (   j   )               ]     ⁡     [               T   A     ⁢   Offset     ⁢                         T   B     ⁢           ⁢   Offset           ]                 [   11   ]               
wherein
         T A (j) represents motor torque for the first electric machine  56 ,   T B (j) represents motor torque for the second electric machine  72 ,   T I (j) represents engine input torque to the transmission  10 ,   T O (j) is the output torque out of the transmission  10 ,   N I (j) represents input speed, and   a 11 , a 12 , a 21 , a 22 , b 11 , b 21  are known parametric values based upon hardware gear and shaft interconnections determined for the specific application and for the specific operating range state.       

     The output torque (‘T O (j)’), motor torques (‘T A (j)’) and (‘T B (j)’), and associated battery powers and power cost inputs are input to a cost function  450 , which executes to determine a power cost (‘Pcost(j)’) for operating the powertrain at the candidate input power or candidate input torque and candidate input speed in response to the operator torque request in the candidate operating range state. The 1-D search engine  415  iteratively generates candidate input torques over the range of input torques and determines the power costs associated therewith to identify a preferred input torque (‘Ti*’) and associated preferred power cost (‘P*cost’). The preferred input torque (‘Ti*’) comprises the candidate input torque within the range of input torques that results in a minimum power cost of the candidate operating range state, i.e., the preferred power cost. The 2-D search engine  410  iteratively generates the candidate input powers and candidate input speeds over the range of input speeds and range of input powers and determines the power costs associated therewith to identify a preferred input power (‘Pi*’) and preferred input speed (‘Ni*’) and associated preferred cost (‘P*cost’). The preferred input power (‘Pi*’) and preferred input speed (‘Ni*’) comprises the candidate input power and candidate input speed that result in a minimum power cost for the candidate operating range state. 
       FIG. 10  graphically illustrates the input speed determined without compensating for inertial effects and a preferred input speed determined with compensating for inertial effect during transitions between G 1  and M 1 . In this depiction, compensating for inertial effects increases preferred input speed determinations for the fixed gear mode operating range states greater than preferred input speed determinations for the mode operating range states. The preferred input speed determinations affect power of the engine  14 , e.g., additional preferred input speed requires additional engine power. 
     The additional power required to increase or decrease the engine input speed N I  affects power cost determinations (‘Pcost’) for each operating range state. When motor torques T A  and T B  are determined based upon the inertia effects resulting from inclusion of the acceleration terms {dot over (N)} I  and {dot over (N)} O  in the optimization function  440  additional power required to increase or decrease the engine input speed N I  is compensated in the power cost determinations. 
     As depicted in  FIG. 10 , the additional power affects a trajectory of the input speed N I  based upon the operating range state selection. When inertia is uncompensated, the power cost determinations do not account for the additional power required to increase or decrease the engine input speed N I . The operating range state selection is based upon non-preferred power cost determinations thereby resulting in a trajectory of the input speed N I  that is less efficient. As  FIG. 10  shows for an exemplary situation, inertia compensation increases operating time in M 1  and decreases operating time in fixed gear mode operating range state G 1  based upon a higher calculated power cost for operating in G 1  thereby increasing the total powertrain system efficiency. 
     The state stabilization and arbitration block  280  selects a preferred transmission operating range state (‘Hybrid Range State Des’) which preferably is the transmission operating range state associated with the minimum preferred power cost for the allowed operating range states output from the operating range state analyzer  260 , taking into account factors related to arbitrating effects of changing the operating range state on the operation of the transmission to effect stable powertrain operation. The preferred input speed (‘Ni_Des’) is the engine input speed associated with the preferred engine input comprising the preferred engine input speed (‘Ni*’), the preferred engine input power (‘Pi*’), and the preferred engine input torque (‘Ti*’) that is responsive to and preferably meets the operator torque request for the selected preferred operating range state. 
     It is understood that modifications are allowable within the scope of the disclosure. The disclosure has been described with specific reference to the preferred embodiments and modifications thereto. Further modifications and alterations may occur to others upon reading and understanding the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the disclosure.