Flywheel Assembly Parasitic Load Minimization
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Solution Overview
Problem
Flywheel energy storage devices face inefficiencies due to mechanical losses through transmissions and parasitic loads, particularly when positioned upstream or downstream of the transmission, and high-speed flywheels experience increased friction, reducing energy storage capacity.
Innovation Solution
A flywheel assembly with a controller that determines optimal speeds for multiple flywheels based on their parasitic load profiles, allowing for selective coupling upstream or downstream of the transmission to minimize mechanical losses and manage parasitic loads, thereby improving efficiency across different operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flywheel is positioned upstream of the transmission, then the flywheel can be efficiently spun up during start up, but mechanical losses through the transmission reduce energy capture during regenerative braking
Solution Approach 1:
The system divides the flywheel energy storage function into two separate physical locations: an upstream flywheel for spin-up operations and a downstream flywheel for regenerative braking energy capture. This segmentation allows each flywheel to be optimized for its specific function, resolving the contradiction between spin-up efficiency and regenerative braking efficiency.
Solution Approach 2:
The transmission system acts as an intermediary that enables selective coupling between flywheels and different drivetrain components. Through clutch mechanisms, the system can route energy flow to connect the appropriate flywheel to the engine for spin-up or to the wheels for regenerative braking, eliminating the need for a single flywheel to perform conflicting functions.
2Loss of energy
If the flywheel is positioned downstream of the transmission, then mechanical losses are reduced during regenerative braking, but the drivetrain cannot efficiently spin up the flywheel during start up
Solution Approach 1:
The system separates the spin-up function and regenerative braking function into different flywheels located at different positions in the drivetrain. The upstream flywheel handles spin-up operations where high speed is critical, while the downstream flywheel handles regenerative braking where energy capture efficiency is critical.
Solution Approach 2:
The dual-flywheel system collectively provides both spin-up capability and regenerative braking capability that a single flywheel position cannot achieve. The system as a whole becomes multi-functional, with each individual flywheel specialized for its specific function.
3Quantity of substance
If high-speed flywheels are used to increase energy storage capacity, then more energy can be stored, but friction forces increase and reduce efficiency
Solution Approach 1:
The system divides the total energy storage capacity across multiple flywheels operating at different speed ranges. Rather than one high-speed flywheel generating high friction, multiple flywheels share the energy storage function, with each operating at optimized speeds that balance capacity and friction losses.
Solution Approach 2:
The system changes the operating parameters of each flywheel based on its function and position. Upstream flywheels operate at higher speeds for spin-up, while downstream flywheels operate at lower speeds for energy capture, optimizing the balance between energy storage capacity and friction losses for each unit.
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 solution enhances the overall efficiency of flywheel energy storage by reducing mechanical losses and parasitic loads, allowing for more effective energy capture and storage across various modes of operation, including regenerative braking and engine assist.
Implementation Method 1
Flywheels are generally known in the art for storing energy... the flywheel may provide additional power to the wheels, thereby reducing flywheel speed
Implementation Method 2
Friction forces, for example, which resist the rotation of the flywheel body, are generally related to flywheel speed and environment... the flywheel body may be contained in a housing that is maintained at a partial vacuum pressure
Data Source
AI summary
A flywheel assembly may include first and second flywheels having respective first and second flywheel parasitic load profiles. Operating speeds of the first and second flywheels may be selected based at least in part on the first and second flywheel parasitic loads. The operating speeds may be determined such that an aggregate of the first and second flywheel parasitic loads is minimized, thereby increasing the efficiency of the flywheel assembly.