HEV Regenerative Braking Control With Engaged Engine Clutch
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Solution Overview
Problem
In hybrid electric vehicles, the existing regenerative braking systems face challenges with low control accuracy and durability issues due to the disconnection of the Hybrid Starter Generator (HSG) from the driving axle during braking, leading to delayed reacceleration and increased hydraulic braking wear.
Innovation Solution
A method and system for regenerative braking control that keeps the engine clutch engaged during braking when the total braking amount exceeds the base deceleration torque, allowing both motors to contribute to regenerative braking, and uses hydraulic braking only when necessary, thereby reducing hydraulic braking wear and enabling quicker reacceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine clutch is disengaged during braking to separate the HSG from the driving axle, then the HSG can avoid unnecessary wear and operational complexity, but regenerative braking effectiveness is reduced and reacceleration is delayed
Solution Approach 1:
The engine clutch is designed to dynamically switch between engaged and disengaged states based on real-time driving conditions. During braking, the clutch remains engaged to enable HSG regenerative braking, and during reacceleration, it remains engaged to allow rapid engine response, eliminating the need for disengagement and reengagement cycles
Solution Approach 2:
The engine clutch serves multiple functions: it connects the engine to the transmission during normal driving, remains connected during braking to enable HSG regenerative braking (unlike conventional systems that disengage), and allows rapid reacceleration by maintaining engagement. This multi-functionality resolves the contradiction by making the clutch beneficial in both braking and reacceleration phases
2Power
If the HSG is connected to the engine through a pulley and belt for regenerative braking, then the HSG can contribute to braking torque, but control accuracy is reduced due to belt slip and belt durability is adversely influenced
Solution Approach 1:
The belt and pulley components are extracted (removed) from the HSG connection system. Instead of using a belt-driven connection, the HSG is directly coupled to the engine crankshaft, eliminating the intermediate transmission elements that cause slip and reduce control accuracy while maintaining the HSG's ability to generate regenerative braking torque
Solution Approach 2:
The belt and pulley act as unwanted intermediaries between the HSG and engine that introduce slip and reduce precision. By removing these intermediaries and creating a direct connection, the patent eliminates the source of control accuracy problems while preserving the power transmission function
3Force
If hydraulic braking is used to supplement regenerative braking when total braking amount exceeds maximum regenerative torque, then the required braking force can be achieved, but wear on the hydraulic braking system increases
Solution Approach 1:
The HSG is kept continuously connected to the driving axle through the engaged engine clutch, enabling continuous regenerative braking action during braking events. This continuous regenerative braking reduces the need for hydraulic braking intervention, thereby reducing wear on the hydraulic braking system while maintaining adequate total braking force
Solution Approach 2:
The system recovers kinetic energy during braking through the HSG by converting it to electrical energy for battery charging. By maximizing this energy recovery through continuous HSG engagement, the system reduces reliance on hydraulic braking, thereby extending the duration and durability of the hydraulic braking system
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 enhances regenerative braking effectiveness, reduces hydraulic braking reliance, and minimizes wear on the hydraulic braking system, allowing for faster vehicle reacceleration and improved fuel efficiency.
Implementation Method 1
additionally charging a battery using regenerative braking of the first motor when the engine clutch has been engaged in consideration of the total braking amount and charge power by regenerative braking of the second motor is lower or less than charge limit power of the battery
Data Source
AI summary
A hybrid electric vehicle (HEV) that can perform more efficient regenerative braking and a method of regenerative braking control for the same are disclosed. The method of regenerative braking control includes determining a total braking amount when a braking request is generated in a HEV including a first motor connected to an engine, a second motor directly connected to an input side of a transmission, and an engine clutch having a first end connected to the first motor and a second end connected to the second motor. The method also includes charging a battery using regenerative braking of the first motor when the engine clutch has been engaged in consideration of at least the total braking amount and charge power by regenerative braking of the second motor is less than charge limit power of the battery.