Hybrid Vehicle Torque Control for Smooth Lash Crossing

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Solution Overview

Problem

Vehicle creep causes perceptible lash crossing events and torque shocks due to torque direction reversals, leading to discomfort and reduced durability in hybrid vehicles.

Innovation Solution

A control system that limits the rate of torque change using a lash crossing protection rate limiter and inhibits initial torque increase upon removal of the limiter, employing a PI/PID speed controller to ensure smooth transitions during vehicle creep.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If vehicle creep control is implemented with torque direction reversal, then vehicle creep function is achieved, but lash crossing events and torque shocks occur causing discomfort and reduced durability

Engineering Contradiction:

Improvevehicle creep functionVSAvoidlash crossing events and torque shocks

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The control system detects when torque reversal is about to occur and applies a rate limiter before the actual reversal happens. This preliminary action prevents the sudden torque change that causes lash crossing events by proactively limiting the rate of torque change during the transition period

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The rate limiter acts as a cushioning mechanism that absorbs and dampens the abrupt torque reversal. By limiting the maximum rate of torque change, it creates a buffer that prevents the harsh torque shocks from reaching the drivetrain components and occupants

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If rate of torque change is limited using a rate limiter, then jerk is reduced during torque reversal, but torque response becomes slower

Engineering Contradiction:

Improvejerk during torque reversalVSAvoidtorque response speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The control system dynamically adjusts the torque request based on operating conditions. The rate limiter is applied selectively during torque reversal events rather than continuously, allowing full torque response speed during normal operation while preventing excessive jerk only when needed during direction changes

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the torque parameter behavior based on the operational state. During normal creep operation, torque can change freely to maintain response speed. During detected reversal events, the rate of change parameter is temporarily constrained to reduce jerk, then restored afterward

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12420794B2Hybrid vehicle speed and torque control

Publication Date: 2025.09.23 JAGUAR LAND ROVER LTD

AI summary

Aspects of the present invention relate to a method and to a control system for controlling an electric traction motor of a vehicle, the control system comprising one or more controllers, wherein the control system is configured to: limit a rate of change of torque requested from the electric traction motor for changing speed towards a speed target, in dependence on a lash crossing protection rate limiter; and upon removal of the limit prior to the speed reaching the speed target, inhibit initial increase of a torque requested from the electric traction motor for changing speed towards the speed target.