Regenerative Braking Buffering for Battery Charge-Rate Limits
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Solution Overview
Problem
Electric regenerative braking systems are limited in recovering kinetic energy during braking due to the slow charging rate of batteries, which exceeds the rate at which electricity is generated, leading to reliance on standard brakes to dissipate excess energy as heat.
Innovation Solution
An electric regenerative braking system that uses an electric motor to convert kinetic energy into electrical potential energy, which is stored in an energy accumulator with increasing resistance, and then supplied to a battery, with a controller managing the braking torque through a variable resistor based on the accumulator's resistance, allowing for efficient energy capture and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking generates electricity during braking, then kinetic energy is converted to electrical energy, but the battery cannot accept electricity fast enough, causing energy loss
Solution Approach 1:
The patent introduces an energy accumulator (supercapacitor) as an intermediary component between the electric motor and the battery. The accumulator receives high-rate charging from the motor during braking and then transfers energy to the battery at a controlled rate, resolving the mismatch between generation and acceptance speeds.
Solution Approach 2:
The energy storage function is segmented into two separate components: the energy accumulator for high-rate temporary storage and the battery for long-term storage. This segmentation allows each component to operate within its optimal performance range.
2Force
If standard brakes are used to dissipate excess kinetic energy, then vehicle stopping is achieved, but energy is lost as heat
Solution Approach 1:
The system converts the previously harmful heat dissipation into beneficial energy storage. By using the energy accumulator to capture kinetic energy during braking, the system transforms waste heat energy into stored electrical energy that can be reused.
Solution Approach 2:
The patent merges regenerative braking and friction braking into a unified system. The controller coordinates both braking mechanisms, allowing the electric motor to provide regenerative braking when the accumulator has capacity and friction brakes to supplement when needed, optimizing both stopping performance and energy recovery.
3Reliability
If the battery is protected from overcharging, then battery lifespan is extended, but energy transfer from the motor is limited
Solution Approach 1:
The energy accumulator serves as a buffer that decouples the motor from the battery. It absorbs energy from the motor at high rates without concern for battery charging limits, then transfers energy to the battery at safe rates, protecting the battery while maximizing energy capture.
Solution Approach 2:
The energy accumulator performs preliminary energy storage before transferring to the battery. This preliminary action allows the system to capture all available regenerative energy first, then gradually transfer it to the battery when conditions are favorable.
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 system effectively captures and stores kinetic energy as electrical potential energy, reducing the reliance on standard brakes and minimizing energy loss as heat, while also protecting the battery from overcharging by controlling the energy transfer rate.
Implementation Method 1
an electric motor to supply the electrical potential energy
Implementation Method 2
an energy accumulator that increases in electrical resistance as more electrical potential energy is stored
Implementation Method 3
an electronic controller including a variable resistor for controlling a braking torque of the electric motor based on the resistance of the variable resistor and the resistance of the energy accumulator
Data Source
AI summary
An electric regenerative braking system is provided for capturing kinetic energy as electrical potential energy during vehicle braking (also referred to as a braking event). The electric regenerative braking system captures the kinetic energy from a shaft of the vehicle using an electric motor to generate electrical potential energy from the kinetic energy. The generated electrical potential energy is supplied to an energy accumulator that increases in electrical resistance as more electrical potential energy is stored. The electrical potential energy stored in the energy accumulator is used to charge a battery. The electric regenerative braking system uses a controller having a variable resistor to control a braking torque of the electric motor. That is, the controller modulates a resistance of the variable resistor based on the resistance of the energy accumulator, such that the resistance of the variable resistor is reduced as the resistance of the energy accumulator increases.