Dual Energy Storage for EV Regenerative Braking Surges
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Solution Overview
Problem
Existing electric and hybrid vehicles face inefficiencies in energy storage during braking or downhill travel due to limitations in accumulator charging capacity, often requiring either power limitation or over-dimensioned, expensive energy storage systems.
Innovation Solution
A dual energy storage system comprising a primary accumulator for high energy density and a secondary energy store, such as a supercapacitor or flywheel, with higher power density, allowing for intermediate storage and efficient utilization of energy generated during braking or downhill travel without damaging the accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an accumulator is used for energy storage in electric vehicles, then energy can be stored electrochemically with high energy density, but the maximum charging capacity is limited and high power during braking can damage the accumulator
Solution Approach 1:
The energy storage system is segmented into two distinct components: an accumulator for energy storage and a capacitor for power management. Each component is optimized for its specific function, with the accumulator providing high energy density and the capacitor providing high power density, thereby resolving the contradiction between energy storage capacity and charging power.
Solution Approach 2:
The capacitor acts as an intermediary between the regenerative brake and the accumulator. It temporarily absorbs high power surges during braking, protecting the accumulator from damage, and then transfers energy to the accumulator when appropriate, enabling full utilization of regenerative energy without compromising accumulator integrity.
2Reliability
If the accumulator charging capacity is limited to protect the accumulator, then the accumulator is protected from damage, but energy generated during braking or downhill travel is not entirely utilized
Solution Approach 1:
The capacitor serves as a buffer intermediary that captures excess regenerative energy during braking that would otherwise be lost due to accumulator charging limits. It stores this energy temporarily and releases it when the accumulator is ready to accept charge, ensuring complete utilization of regenerative energy while protecting the accumulator.
Solution Approach 2:
The capacitor performs preliminary energy storage during braking events, capturing high power surges before they can damage the accumulator. This preliminary action allows the system to preserve all regenerative energy and then transfer it to the accumulator in controlled amounts, preventing energy loss while maintaining accumulator protection.
3Power
If an over-dimensioned accumulator is employed to handle high power during braking, then full power can be utilized, but the accumulator becomes comparatively over-expensive
Solution Approach 1:
The system segments the power handling function from the energy storage function. The capacitor, which is less expensive for high power applications, handles the high power surges during braking, while the smaller, more cost-effective accumulator provides energy storage. This segmentation allows full power utilization without requiring an over-dimensioned and expensive accumulator.
Solution Approach 2:
The capacitor acts as a cost-effective, short-term energy buffer that can be repeatedly charged and discharged without degradation. It handles the high power, short-duration braking energy at a lower cost than would be required to upgrade the accumulator, enabling full power utilization while controlling overall system cost.
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
Enables full utilization of energy generated during braking or downhill travel without damaging the accumulator, using a cost-effective secondary energy store to handle high power surges and a primary energy store for routine energy supply, optimizing energy management and reducing the need for over-dimensioned accumulators.
Implementation Method 1
For the storage of energy, accumulators are customarily employed, which store electrical energy by an electrochemical principle
Implementation Method 2
A dual energy storage system comprising a primary accumulator for high energy density and a secondary energy store, such as a supercapacitor or flywheel
Implementation Method 3
A dual energy storage system comprising a primary accumulator for high energy density and a secondary energy store, such as a supercapacitor or flywheel
Data Source
AI summary
A system for an electrically-driven vehicle includes at least one first energy store, which is of an accumulator type, and at least one second energy store, of a type which differs from an accumulator type. The second energy store has an energy density lower than an energy density of the first energy store, and has a power density higher than a power density of the first energy store. The first energy store and the second energy store are designed to supply electrical energy for an electric drive of the vehicle.