Regenerative Braking Control for Hybrid Vehicles

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Solution Overview

Problem

In hybrid vehicles, the conventional priority of hydraulic braking over regenerative braking leads to a loss of regenerative braking energy at the early stage of braking, resulting in fuel efficiency aggravation and discomfort during braking, due to the slow response of regenerative braking and initial hydraulic braking pressure application.

Innovation Solution

A method that determines a possible amount of regenerative braking at the early stage of braking, distributing it as both regenerative and hydraulic braking, allowing regenerative braking to be performed first, thereby maximizing energy recovery and improving braking stability by estimating the regenerative braking amount based on motor and battery conditions, speed changes, and transmission gear ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydraulic braking is performed first at the early stage of braking to secure braking safety, then braking reliability is improved, but the amount of regenerative braking is reduced causing fuel ratio aggravation

Engineering Contradiction:

Improvebraking safetyVSAvoidregenerative braking energy

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system performs preliminary determination of the possible amount of regenerative braking before actual braking occurs. By calculating the maximum regenerative braking capacity based on motor and battery conditions in advance, the system can immediately activate regenerative braking at the early stage without delay, thereby maximizing energy recovery while ensuring braking safety through pre-assessed capability

Inventive Principle:

Principle #10Preliminary action

2Speed

If hydraulic braking pressure is applied initially to ensure braking response, then braking response time is improved, but regenerative braking amount is lost due to slow response

Engineering Contradiction:

Improvebraking response speedVSAvoidregenerative braking energy

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The system calculates the possible amount of regenerative braking in advance based on motor temperature, battery charge condition, and transmission gear ratio. This preliminary assessment enables the system to immediately activate regenerative braking when braking is requested, eliminating the delay associated with checking regenerative capability during braking and maximizing energy recovery from the earliest moment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically determines the regenerative braking amount by changing parameters such as motor temperature, battery charge condition, and transmission gear ratio. By continuously monitoring these parameters and adjusting the regenerative braking amount accordingly, the system optimizes the balance between braking response speed and energy recovery efficiency

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If regenerative braking amount is increased to improve fuel ratio, then energy recovery is improved, but braking comfort deteriorates due to sudden torque application

Engineering Contradiction:

Improveregenerative braking energyVSAvoidbraking comfort

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The system determines the regenerative braking amount by dynamically changing parameters including motor temperature, battery charge condition, and transmission gear ratio. This parameter-based adjustment allows the system to optimize the balance between maximizing energy recovery and maintaining braking comfort, applying appropriate torque gradually rather than suddenly

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system dynamically adjusts the regenerative braking amount based on real-time vehicle conditions and driver braking intent. By continuously adapting the torque application rate and amount according to changing parameters, the system ensures smooth torque delivery that maintains braking comfort while maximizing energy recovery potential

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach maximizes regenerative braking energy recovery, improves fuel efficiency, and reduces braking discomfort by ensuring regenerative braking is initiated before hydraulic braking, thus enhancing the overall braking experience and fuel ratio.

Implementation Method 1

regenerative braking is a technology which generates electric energy using a motor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

stores generated electric energy using a high voltage battery

Methodology Applied

Scientific EffectElectrochemical energy storage: Battery (electricity)

Data Source

PatentUS9533581B2Method for determining amount of regenerative braking

Publication Date: 2017.01.03 HYUNDAI MOTOR CO LTD

AI summary

A method for determining an amount of regenerative braking includes: determining a possible amount of regenerative braking at a time of braking a vehicle; distributing a first amount of regenerative braking up to the possible amount of regenerative braking as the amount of regenerative braking; distributing a second amount of regenerative braking remaining from the possible amount of regenerative braking as an amount of hydraulic braking; and performing, first, regenerative braking by issuing a motor torque instruction according to the possible amount of regenerative braking and, second, friction braking using the amount of hydraulic braking.