Abstract: Systems and methods for operating an internal combustion engine that is coupled to a power split transmission are described. In one example, the internal combustion engine is operated in a speed control mode or a torque control mode in response to a braking torque and a transmission shift command. Operating the engine in the torque control mode may allow the engine to charge a battery while a neutral transmission state is selected.

Abstract: Methods and systems are provided for operating a vehicle that includes an electric machine as a propulsion source. In one example, a motor stall assessment level is generated based on an amount of time that the motor is stalled and an amount of torque that is generated by the motor. Mitigating actions may be performed if the motor stall assessment level exceeds a threshold level or value.

Abstract: Methods and systems are provided, including a method for an electric vehicle battery distribution among at least three motors. The method may comprise selecting a first drive path with at least first and second motors for an open-loop power allocation control, designating a second drive path with at least a third motor for an open-loop or a closed-loop power allocation control, determining a power allocation ratio of each motor relative to a total power; and operating the each motors with adjusted power limits based on the determined power allocation ratios.

Abstract: Methods and systems are provided for operating a vehicle that includes an electric machine as a propulsion source. In one example, a motor stall assessment level is generated based on an amount of time that the motor is stalled and an amount of torque that is generated by the motor. Mitigating actions may be performed if the motor stall assessment level exceeds a threshold level or value.

Abstract: Systems and methods for operating an internal combustion engine that is coupled to a power split transmission are described. In one example, the internal combustion engine is operated in a speed control mode or a torque control mode in response to a braking torque and a transmission shift command. Operating the engine in the torque control mode may allow the engine to charge a battery while a neutral transmission state is selected.

Abstract: Methods and systems are provided for operating a driveline of a hybrid vehicle during conditions when a temperature of a motor/generator is increasing. In one example, a method is provided that adjusts engine speed as a function of motor/generator temperature while maintaining engine power output when driver demand wheel power is constant.

Abstract: Methods and systems are provided for operating a driveline of a hybrid vehicle during conditions when a temperature of a motor/generator is increasing. In one example, a method is provided that adjusts engine speed as a function of motor/generator temperature while maintaining engine power output when driver demand wheel power is constant.

Abstract: A vehicle system includes a vehicle component with a component temperature sensor, and a fluid circuit in fluid communication with the component and with a fluid temperature sensor. A controller is in communication with the component sensor and the fluid sensor. The controller is configured to, in response to a temperature difference between the component sensor and the fluid sensor being greater than a predetermined threshold value, output a flag or a diagnostic code indicative of a fluid level in the fluid circuit. A vehicle diagnostic method and a vehicle are also provided.

Abstract: Methods and systems are provided for operating a driveline of a hybrid vehicle during conditions when a temperature of a motor/generator is increasing. In one example, a method is provided that adjusts engine speed as a function of motor/generator temperature while maintaining engine power output when driver demand wheel power is constant.

Abstract: A vehicle includes a contactor electrically between a charge port and a traction battery, and a controller configured to maintain the contactor in a closed position until a charge current estimate, derived from vehicle load data without sensing current through the contactor or receiving data from a charge station regarding the current, is less than a predetermined threshold. The maintenance of the contactor position is responsive to a charge disconnect request.

Abstract: Methods and systems are provided for adjusting a torque delivered to wheels of an electrically propelled vehicle based on a battery discharge power. In one example, a method may include, during conditions of a lower than threshold battery output power, reducing the torque delivered to the vehicle wheels from a deliverable torque output.

Abstract: Methods and systems for a vehicle such as a plug-in hybrid electric vehicle (PHEV) having a traction battery are for improving the drivability of the vehicle the battery has low discharge limits. The battery may have such low discharge limits due to the battery being cold and/or the battery state-of-charge (SOC) being low. In operation, upon the battery having a discharge limit lower than a threshold while the vehicle is operating in a charge sustain mode, the engine of the vehicle is used to charge the battery to increase the SOC of the battery such that the battery has a discharge limit greater than the threshold. The vehicle is operated in the charge sustain mode using the battery with the increased SOC.

Abstract: Methods and systems are provided for controlling an engine speed in a hybrid vehicle system during steady-state conditions and in response to transient acceleration and/or deceleration requests. In one example, an engine speed is controlled to an optimal engine speed for fuel economy during steady-state conditions, and in response to an acceleration or deceleration request, a target engine speed is obtained from a rate-limited optimal engine speed to vehicle speed ratio, and the engine is controlled to the target engine speed provided the target speed is below a threshold difference from optimal engine speed. In this way, the vehicle system may simulate a fixed ratio transmission during accelerations and decelerations, while maintaining optimal engine speed for fuel economy at steady state.

Abstract: A vehicle system includes a vehicle component with a component temperature sensor, and a fluid circuit in fluid communication with the component and with a fluid temperature sensor. A controller is in communication with the component sensor and the fluid sensor. The controller is configured to, in response to a temperature difference between the component sensor and the fluid sensor being greater than a predetermined threshold value, output a flag or a diagnostic code indicative of a fluid level in the fluid circuit. A vehicle diagnostic method and a vehicle are also provided.

Abstract: Methods and systems for a vehicle such as a plug-in hybrid electric vehicle (PHEV) having a traction battery are for improving the drivability of the vehicle the battery has low discharge limits. The battery may have such low discharge limits due to the battery being cold and/or the battery state-of-charge (SOC) being low. In operation, upon the battery having a discharge limit lower than a threshold while the vehicle is operating in a charge sustain mode, the engine of the vehicle is used to charge the battery to increase the SOC of the battery such that the battery has a discharge limit greater than the threshold. The vehicle is operated in the charge sustain mode using the battery with the increased SOC.

Abstract: A vehicle includes an electric machine, an engine, an engine mount, and a controller. The engine has a base speed that corresponds to a speed of the electric machine and an engine power demand. The engine mount is disposed between the engine and a vehicle structure such as a frame or unibody. The controller is configured to, in response to compression of the engine mount, increase an engine speed to a value that is greater than the base speed to reduce engine lugging.

Abstract: Systems and methods for operating a vehicle that includes a continuously variable transmission are described. The systems and methods adjust engine speed according to one of a plurality of engine speed to vehicle speed profiles so that driveline noise, vibration, and harshness may be reduced. The different engine speed to vehicle speed profiles provide different levels of engine braking.

Abstract: A vehicle includes a contactor electrically between a charge port and a traction battery, and a controller configured to maintain the contactor in a closed position until a charge current estimate, derived from vehicle load data without sensing current through the contactor or receiving data from a charge station regarding the current, is less than a predetermined threshold. The maintenance of the contactor position is responsive to a charge disconnect request.

Abstract: A method for controlling a hybrid electric vehicle includes selecting a first target engine speed in response to a driver power request, calculating an available engine torque at the first target engine speed, adjusting the target engine speed if the available engine torque is insufficient to satisfy the driver power request, and commanding an engine to run at the target engine speed. The first target engine speed is optimized for fuel economy. The calculated available engine torque is less than a calculated maximum engine torque at the target engine speed, such that a torque reserve is maintained for engine vacuum.

Abstract: Methods and systems are provided for controlling an engine speed in a hybrid vehicle system during steady-state conditions and in response to transient acceleration and/or deceleration requests. In one example, an engine speed is controlled to an optimal engine speed for fuel economy during steady-state conditions, and in response to an acceleration or deceleration request, a target engine speed is obtained from a rate-limited optimal engine speed to vehicle speed ratio, and the engine is controlled to the target engine speed provided the target speed is below a threshold difference from optimal engine speed. In this way, the vehicle system may simulate a fixed ratio transmission during accelerations and decelerations, while maintaining optimal engine speed for fuel economy at steady state.