Hybrid Powertrain Torque Coordination for Deceleration

Solution Overview

Problem

Hybrid electric vehicle powertrains face challenges in delivering smooth and consistent torque due to physical differences between engine and motor torque delivery characteristics, along with software-related delays, resulting in magnitude and phase errors during deceleration, such as tip-outs.

Innovation Solution

A control system that reduces engine torque at a first rate and motor torque at a second, greater rate in response to deceleration requests, ensuring the combined torque matches the driver's demand, thereby minimizing phase delays and driveline disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the engine and motor are controlled to deliver torque simultaneously, then the combined torque can meet the driver's demand, but physical differences in delivery characteristics cause magnitude and phase errors resulting in driveline disturbances

Engineering Contradiction:

Improvecombined torque deliveryVSAvoidtorque delivery consistency

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The control system performs preliminary action by predicting the driver's torque demand based on current accelerator pedal position and recent torque history, then proactively adjusts engine and motor torque contributions before the actual demand occurs. This predictive approach compensates for physical delivery differences and software delays, preventing driveline disturbances rather than reacting to them after they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the torque reduction rates of the engine and motor based on real-time operating conditions. During deceleration events, the motor torque is reduced at a different rate than the engine torque, with the control system continuously monitoring and adjusting these rates to maintain smooth combined torque delivery. This dynamic coordination accounts for the different physical delivery characteristics of each torque source.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If separate controlling algorithms are used for engine and motor in different microcontrollers or software modules, then each component can be optimized independently, but software-related delays cause phase errors in combined torque delivery

Engineering Contradiction:

Improveindependent component optimizationVSAvoidsoftware delay

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The control system performs preliminary action by predicting the driver's torque demand based on current accelerator pedal position and recent torque history, then proactively adjusts engine and motor torque contributions before the actual demand occurs. This predictive approach compensates for physical delivery differences and software delays, preventing driveline disturbances rather than reacting to them after they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the actual torque delivery from both engine and motor, comparing it against the predicted demand, and adjusting control parameters in real-time. This closed-loop feedback mechanism compensates for software delays and ensures that the combined torque delivery remains synchronized with driver intent, eliminating phase errors that would otherwise result from separate control algorithms.

Inventive Principle:

Principle #23Feedback

3Speed

If the motor torque is reduced at a high rate during deceleration, then the tip-out response can be improved, but the engine torque must be coordinated to prevent driveline disturbances

Engineering Contradiction:

Improvetorque reduction rateVSAvoiddriveline disturbance

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The system dynamically adjusts the torque reduction rates of the engine and motor based on real-time operating conditions. During deceleration events, the motor torque is reduced at a different rate than the engine torque, with the control system continuously monitoring and adjusting these rates to maintain smooth combined torque delivery. This dynamic coordination accounts for the different physical delivery characteristics of each torque source.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system acts as an intermediary that coordinates between the motor control algorithm and engine control algorithm. It receives the deceleration request, calculates appropriate torque reduction rates for both components, and distributes control commands to ensure they work together harmoniously. This intermediary coordination prevents driveline disturbances that would result from uncoordinated high-rate torque reduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9988041B2System and method for controlling a vehicle powertrain

Publication Date: 2018.06.05 FORD GLOBAL TECH LLC

AI summary

A system and method for controlling a vehicle powertrain including an engine and a motor operable to propel the vehicle includes reducing a torque of the motor at a first torque reduction rate from a torque level above a minimum motor torque in response to a deceleration request. A torque of the engine is reduced at a second torque reduction rate less than the first torque reduction rate in response to the deceleration request.