Unified Regenerative and Friction Braking Control for Hybrid Vehicles
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Solution Overview
Problem
Existing hybrid electric vehicle systems face challenges in effectively integrating regenerative braking with anti-lock braking systems (ABS), leading to reduced energy recapture and potential vehicle instability during anti-lock braking events due to the interaction between regenerative braking torque and friction braking torque.
Innovation Solution
A control system that adjusts both regenerative braking torque and friction braking torque based on a common signal, using weighting coefficients to maintain desired wheel slip ratios during anti-lock braking events, allowing for simultaneous energy recapture and stability maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking torque is applied during anti-lock braking events, then energy recapture is improved, but vehicle stability deteriorates due to wheel lock-up
Solution Approach 1:
The patent combines regenerative braking and friction braking into a unified braking system controlled by a single controller. The controller integrates both braking mechanisms to work together during anti-lock braking events, allowing the regenerative braking torque and friction braking torque to be coordinated through a common control signal and weighting coefficients, thus maintaining vehicle stability while maximizing energy recapture.
Solution Approach 2:
The patent dynamically adjusts the weighting coefficients for regenerative braking and friction braking based on real-time wheel slip conditions. The controller continuously monitors wheel slip ratio and adjusts the distribution of braking torque between regenerative and friction brakes, enabling adaptive optimization of both energy recapture and vehicle stability during anti-lock braking events.
2Loss of energy
If regenerative braking torque is increased to maximize energy recapture, then energy recapture is improved, but wheel slip control deteriorates leading to potential wheel lock-up
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the actual wheel slip ratio and compares it to the desired wheel slip ratio. Based on this feedback, the controller adjusts the regenerative braking torque and friction braking torque in real-time, ensuring that wheel slip remains within the optimal range for both energy recapture and preventing wheel lock-up.
Solution Approach 2:
The patent changes the weighting coefficients as dynamic parameters that determine the distribution of braking torque between regenerative and friction brakes. By adjusting these parameters based on wheel slip conditions, the system optimizes the balance between energy recapture and wheel slip control, preventing wheel lock-up while maximizing regenerative braking effectiveness.
3Manufacturing precision
If friction braking torque is used to maintain wheel slip control, then wheel slip control is improved, but energy recapture deteriorates due to reduced regenerative braking contribution
Solution Approach 1:
The patent applies partial friction braking torque rather than full friction braking, allowing regenerative braking to contribute more significantly to the total braking effort. The weighting coefficients are optimized to provide just enough friction braking torque to maintain wheel slip control while maximizing the regenerative braking contribution, thus improving energy recapture without sacrificing wheel slip control.
4Adaptability or versatility
If separate control systems are used for regenerative braking and friction braking, then control flexibility is improved, but system complexity increases
Solution Approach 1:
The patent merges the control of regenerative braking and friction braking into a single unified control system. The controller uses a common control signal and weighting coefficients to manage both braking mechanisms, reducing system complexity while maintaining the flexibility to optimize the contribution of each braking type based on real-time conditions.
Solution Approach 2:
The controller is designed with multi-functionality to handle both regenerative braking control and friction braking control through a unified architecture. This universal controller can adapt its control strategy based on operating conditions, providing the flexibility of separate control systems while avoiding the complexity of multiple independent control units.
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
The system enables maximum energy recapture during ABS events while maintaining vehicle stability by integrating regenerative and friction braking controls, ensuring optimal performance and reducing the need for frequent ABS activation.
Implementation Method 1
During regenerative braking, an electric machine may operate as a generator to convert the kinetic energy of the vehicle into electrical energy which is in turn used to charge a battery
Implementation Method 2
The friction brakes are configured to apply torque to wheels of the vehicle to slow the vehicle
Data Source
AI summary
A vehicle includes an axle, electric machine, friction, brakes, and a controller. The axle has an input shaft to an open differential and output shaft extending out of the open differential. The electric machine is secured to the input shaft and wheels are secured to the output shafts. The controller is programmed to, in response to an anti-locking braking event, generate a signal indicative of a total torque demand to brake the vehicle based on a difference between a desired and an actual wheel slip ratio, adjust a regenerative braking torque of the electric machine based on signal and a regenerative braking weighting coefficient to maintain or drive actual wheel slip toward the desired wheel slip, and adjust a friction braking torque of the friction brakes based on the signal and a friction braking weighting coefficient to drive actual wheel slip at or toward the desired wheel slip.