EV Braking System Regenerative Range Adjustment
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Solution Overview
Problem
Current braking systems for electric vehicles, particularly in mild hybrids or hybrids with small electric engines, are over-engineered and costly, with limited regenerative braking potential, leading to suboptimal energy recuperation and inconsistent brake feel.
Innovation Solution
A braking system with a brake pedal that has defined regenerative and mechanical braking ranges, where the brake controller adjusts the regenerative-braking range based on the traction battery's state of charge, ensuring maximal recuperation power is applied first, and mechanical brakes are engaged only when necessary, reducing wear and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used to maximize energy recuperation, then fuel efficiency and CO2 reduction are improved, but the brake pedal feel becomes inconsistent when the traction battery is fully charged
Solution Approach 1:
The brake controller dynamically adjusts the regenerative-braking range based on the state of charge of the traction battery. When the battery is fully charged, the controller reduces or eliminates the regenerative-braking range, ensuring that mechanical brakes are engaged at the appropriate pedal positions. This dynamic adjustment maintains consistent brake pedal feel across different battery states while maximizing energy recuperation when possible.
2Power
If both mechanical brake and regenerative brake operate in parallel, then braking power is sufficient, but energy recuperation is suboptimal
Solution Approach 1:
The braking system segments the braking function into distinct ranges: a regenerative-braking range for energy recuperation and a mechanical-braking range for additional braking power. The brake controller activates regenerative braking exclusively within the regenerative-braking range, then transitions to mechanical braking when the pedal displacement exceeds this range. This segmentation ensures optimal energy recuperation while maintaining sufficient total braking power.
3Device complexity
If regenerative braking capacity is limited in mild hybrids, then system complexity is reduced, but energy recuperation potential is insufficient
Solution Approach 1:
The system dynamically adjusts the regenerative-braking range based on the available regenerative braking capacity and battery state of charge. By optimizing the utilization of the limited regenerative braking capacity through adaptive range adjustment, the system maximizes energy recuperation potential without adding complex hardware, maintaining simplicity while improving energy efficiency.
4Power
If mechanical brakes are used to support regenerative braking, then sufficient braking power is achieved, but mechanical brake wear increases
Solution Approach 1:
The braking system segments the braking function into distinct ranges: a regenerative-braking range for energy recuperation and a mechanical-braking range for additional braking power. The brake controller activates regenerative braking exclusively within the regenerative-braking range, then transitions to mechanical braking when the pedal displacement exceeds this range. This segmentation ensures optimal energy recuperation while maintaining sufficient total braking power.
Solution Approach 2:
The system converts the limitation of limited regenerative braking capacity into a benefit by using it as the primary braking method within its operational range, thereby reducing mechanical brake wear. The mechanical brakes are reserved for situations where additional braking power is needed, transforming the insufficient regenerative capacity into an opportunity to minimize friction brake usage and extend their service life.
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 solution enhances fuel efficiency, CO2 reduction, extends the vehicle's range, provides a consistent brake feel, and reduces mechanical brake wear by optimizing regenerative braking utilization and minimizing mechanical braking.
Implementation Method 1
employ recuperative and/or regenerative braking techniques to utilize a maximum amount of kinetic energy of the vehicle by using the electric engine as a generator to recharge a traction battery
Implementation Method 2
a mechanical brake (e.g. a vacuum pressure actuated friction brake for braking the wheels)
Data Source
AI summary
A braking system for braking an electric vehicle is provided. The system includes a brake pedal having a regenerative-braking range of pedal displacement from an initial position of the brake pedal to a maximal-recuperation position of the brake pedal, and a mechanical-braking range of pedal displacement starting from the maximal-recuperation position of the brake pedal. A brake controller activates deceleration of the vehicle based on the pedal displacement. The brake controller activates deceleration of the electric vehicle based on regenerative braking within the regenerative-braking range and based on mechanical braking within the mechanical-braking range. The regenerative-braking range is adjusted based on a state of charge of a traction battery of the electric vehicle.