Hybrid Vehicle Braking Control via Preliminary Torque Calculation

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Solution Overview

Problem

Hybrid electric vehicles experience degradation in drivability and regenerative braking efficiency due to communication delays among control units, leading to reduced responsiveness and incorrect hydraulic braking applications during regenerative braking.

Innovation Solution

A braking control method that involves determining the total braking amount by a first controller, transmitting a regenerative braking request to a second controller, calculating the regenerative braking execution amount based on the motor's state, and adjusting the frictional braking force accordingly to minimize communication delays and enhance responsiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If communication is performed among control units (iBAU, HCU, MCU) to determine regenerative braking torque, then braking force distribution can be achieved, but communication delay degrades drivability and responsiveness

Engineering Contradiction:

Improvebraking force distribution accuracyVSAvoidcommunication delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary determination of regenerative braking torque by the HCU based on brake pedal manipulation amount before final execution. This preliminary action allows the HCU to calculate the regenerative braking torque in advance, reducing the need for repeated communication cycles during actual braking execution and thereby minimizing communication delay impact on responsiveness

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If maximum braking amount is used for regenerative braking, then fuel economy is enhanced, but responsiveness degrades due to communication delay

Engineering Contradiction:

Improvefuel economyVSAvoidbraking responsiveness

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The HCU determines the regenerative braking torque in advance based on the brake pedal manipulation amount and system state, allowing maximum regenerative braking to be utilized immediately without waiting for communication delays. This preliminary determination enables the system to achieve maximum fuel economy while maintaining responsive braking performance

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If multiple communication cycles are performed to determine regenerative braking torque, then accurate braking force distribution is achieved, but communication delay increases

Engineering Contradiction:

Improvebraking torque allocation accuracyVSAvoidcommunication time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The HCU performs preliminary calculation of regenerative braking torque based on brake pedal manipulation amount and system state, determining the torque allocation in advance. This eliminates the need for multiple communication cycles during braking execution, achieving both accurate torque allocation and reduced communication time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The HCU acts as an intermediary that receives the brake pedal manipulation amount from the iBAU and directly calculates the regenerative braking torque without requiring multiple communication cycles with the MCU. This intermediary role streamlines the communication process while maintaining accurate braking force distribution

Inventive Principle:

Principle #24Intermediary (Mediator)

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 allows for more efficient regenerative braking, improved drivability, and increased stability by directly calculating the regenerative braking execution amount, reducing the impact of communication delays and ensuring braking linearity, even in failure situations.

Implementation Method 1

the motor operates as a generator, together with the existing hydraulic frictional brake, during braking, thereby converting kinetic energy of the vehicle into electrical energy

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11312240B2Hybrid electric vehicle and braking control method thereof

Publication Date: 2022.04.26 HYUNDAI MOTOR CO LTD

AI summary

A hybrid electric vehicle and a braking control method thereof are provided. The method includes determining, by a first controller, a total braking amount corresponding to a brake pedal manipulation amount and transmitting a regenerative braking request corresponding to at least a portion of the total braking amount to a second controller. A state of a regenerative braking system having a motor and a battery is determined and a regenerative braking execution amount is calculated by selectively using a first torque corresponding to a torque command transmitted to a third controller to operate the motor based on the regenerative braking request or a second torque measured by the third controller based on the determined state. A braking force of a frictional brake is determined based on the calculated regenerative braking execution amount and the total braking amount.