Regenerative Braking Transition Timing for Electrified Vehicles
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Solution Overview
Problem
Existing electrified vehicles inefficiently utilize regenerative braking due to fixed start times for braking transitions, reducing regenerative braking energy, especially in light braking scenarios.
Innovation Solution
A method to vary the start point of braking transitions based on vehicle and road conditions, determining a minimum transition time and start vehicle speed to optimize regenerative braking energy by integrating hydraulic and regenerative braking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the start time of braking transition is fixed based on vehicle speed, then the control system is simple, but the regenerative braking energy is reduced due to premature transition in light braking scenarios
Solution Approach 1:
The braking transition control system dynamically adjusts the start time of braking transition based on real-time driving conditions (braking type, vehicle speed, road gradient) rather than using a fixed speed threshold. This allows the system to optimize regenerative braking energy recovery by delaying transition in light braking scenarios while maintaining simple control logic through predefined braking type classification.
Solution Approach 2:
The system changes the control parameter from a single fixed vehicle speed threshold to a multi-parameter decision framework that includes braking type classification, vehicle speed, and road gradient. This enables adaptive adjustment of braking transition timing to maximize energy recovery without significantly increasing system complexity.
2Stability of the object's composition
If the braking transition starts early to ensure smooth transition, then the transition smoothness is improved, but the regenerative braking energy is reduced
Solution Approach 1:
The system dynamically determines the optimal braking transition start time based on the classified braking type and current vehicle speed, rather than using a fixed early transition threshold. This allows the transition to start at the latest possible moment while still ensuring smoothness, thereby maximizing regenerative braking energy recovery.
Solution Approach 2:
The system performs preliminary classification of braking type (hard, intermediate, light) based on driver input and vehicle conditions before determining the braking transition timing. This preliminary action enables the system to pre-calculate the optimal transition start time that balances smoothness requirements with energy recovery optimization.
3Ease of operation
If the regenerative braking amount is reduced early in braking transition, then the hydraulic braking amount can increase smoothly, but the overall energy recovery is decreased
Solution Approach 1:
The system dynamically adjusts the rate and timing of regenerative braking reduction based on the classified braking type, rather than using a fixed reduction schedule. This allows the system to maintain regenerative braking at maximum levels for longer periods in light braking scenarios while still ensuring smooth transition to hydraulic braking when needed.
Solution Approach 2:
The system maintains continuous regenerative braking action for as long as possible by delaying the transition to hydraulic braking, rather than prematurely reducing regenerative braking. This ensures the useful energy recovery action continues uninterrupted, maximizing total energy recovery while maintaining braking smoothness through proper transition management.
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
Maximizes regenerative braking energy and improves fuel economy by adjusting the start of braking transitions dynamically, ensuring efficient energy recovery.
Implementation Method 1
a vehicle provided with an electric motor as a driving source (hereinafter, referred to as an 'electrified vehicle' for convenience), for example, an electric vehicle (EV), a hybrid electric vehicle (HEV), a fuel cell electric vehicle (FCEV) and the like can charge a battery by converting kinetic energy into electrical energy during braking
Implementation Method 2
a brake pad is contacted with a disk or drum rotating together with a wheel by applying hydraulic pressure and braking is occurred through friction, and all kinetic energy of the vehicle is converted into heat energy
Data Source
AI summary
A braking control method of an electrified vehicle provided with an electric motor as a driving source may include the steps of starting regenerative braking when a required braking amount is obtained; determining a minimum transition time which is a minimum time required for braking transition from the regenerative braking to hydraulic braking according to a maximum response slope of a hydraulic braking device of the vehicle; determining braking deceleration according to the required braking amount and a road surface condition; determining a start vehicle speed of the braking transition according to the minimum transition time, the braking deceleration, and an end vehicle speed of the braking transition; and starting the braking transition upon determining that the start vehicle speed of the braking transition is reached during the regenerative braking.