Flywheel Energy Storage: in Automotive Engineering

Formula Symbols
Acknowledgments
Summary
Contents
Abbreviations
1: Introduction
	1.1 Structure of this Book
	1.2 Motivation for a Holistic Assessment of the System ``Energy Storage-Vehicle-Environment´´
	1.3 Initial Situation: Europe in the Energy Revolution
	1.4 The Role of the Transport Sector
	1.5 The Future of Transportation
	References
2: Complexity, Importance, and Overall System Dependency of the Vehicle Operating Strategy
	2.1 A Holistic View: Vehicle, Driver, and Environment
	2.2 Subsystem of Flywheel Energy Storage
		2.2.1 Fundamentals of Kinetic Energy Storage
		2.2.2 Differentiation According to Transmission of the Stored Energy
			2.2.2.1 Purely Mechanical FESS
			2.2.2.2 Electromechanical FESS
		2.2.3 System Components of a FESS
	2.3 State of the Art in the Field of Flywheel Energy Storage Systems
		2.3.1 Existing Systems: Stationary FESS
		2.3.2 Mobile Flywheel Energy Storage Systems for Vehicles
	References
3: Supersystem of Mobile Flywheel Energy Storage
	3.1 Vehicle and Vehicle Topology
	3.2 Features of the Primary Drive
	3.3 Properties of Mobile Energy Storage Devices
	3.4 Geography, Infrastructure, and Intended Use of the Vehicle
		3.4.1 Geography and Infrastructure
		3.4.2 Intended Use of the Vehicle
	3.5 Driver and Energy Psychology
	References
4: Interaction Between Subsystem and Supersystem of Mobile Flywheel Energy Storage
	4.1 Examples of Direct Influence on the Super- and Subsystem of FESS
	4.2 Optimization of the Supersystem
		4.2.1 Influence of the Driving Cycle on the FESS
		4.2.2 Energy Requirements of the Vehicle
			4.2.2.1 Theoretically Recoverable Energy
			4.2.2.2 Effective Speed Range for Regenerative Braking
		4.2.3 Profitability of a FESS in a Vehicle
	References
5: Optimizing the Supersystem of Mobile Energy Storage
	5.1 Emotion Versus Ratio: Passenger Car Versus Commercial Vehicle
	5.2 Aspects of the Supersystem of Public Transport and Commercial Vehicles
		5.2.1 Energy Efficiency of Commercial Vehicles
			5.2.1.1 Simulation of Driving Cycles and Operating Strategies in Public Transport
		5.2.2 Operating Conditions for Hybrid Propulsion Systems and Energy Storage Requirements
	5.3 Individual Transport and Personal Cars
		5.3.1 Aspects of the Supersystem ``Personal Car´´
		5.3.2 Driver and Psychology
		5.3.3 Target Characteristics of Mobile Flywheel Energy Storage Devices
			5.3.3.1 Economic Consideration
	5.4 Energetic Threshold Specifications
		5.4.1 Determination of Energetic Threshold Specifications for FESS
	5.5 Relevant Findings of the System Analysis
		5.5.1 Summary: Optimization of the Supersystem of a FESS
		5.5.2 General, Desirable FESS Improvements
	References
6: Subsystem Optimization
	6.1 Deviation of Desired from Actual Characteristics
		6.1.1 Analysis of the Cost and Weight of the System Components of Two FESS Prototypes
	6.2 Internal System Interdependencies: Interactions Between Critical Components
		6.2.1 Categorization of the Interdependencies
		6.2.2 Critical Interdependencies in the FESS Subsystem
		6.2.3 Identification of Critical Components
			6.2.3.1 The Bearing System as Technical Enabler
	6.3 Results: Critical Components in FESS
	References
7: Rotors for Mobile Flywheel Energy Storage
	7.1 Essential Physical Relationships of FESS Rotor Design
	7.2 Analysis of Existing Systems/State of the Art
		7.2.1 Composite Flywheels
			7.2.1.1 Advantages of Composite Flywheel Rotors
			7.2.1.2 Disadvantages of Composite Rotors
		7.2.2 Steel Flywheels
			7.2.2.1 Development Goals for Steel Rotors
	7.3 Requirements Derived from the Supersystem Analysis
	7.4 Solution Approach/Case Study: CMO Rotor
		7.4.1 System Description Clean Motion Offensive Flywheel
		7.4.2 The CMO Rotor Concept
			7.4.2.1 Balancing of the CMO Rotor
			7.4.2.2 Burst Behavior of the CMO Rotor
	7.5 Solution Approach/Case Study: FIMD Flywheel
		7.5.1 Structure of the FIMD Rotor
			7.5.1.1 Choice of Material
			7.5.1.2 Assembly and Conditioning of the Rotor
		7.5.2 Burst Testing the FIMD Rotor
			7.5.2.1 Qualitative Postmortem Analysis
		7.5.3 Summary of Results: Fully Integrated Multi-Disk Rotor (FIMD)
	References
8: Flywheel Energy Storage Housing
	8.1 Requirements Derived from Supersystem Analysis
	8.2 Safety Requirements for Mobile Energy Storage Devices
	8.3 Analysis of Existing Systems/State of the Art
		8.3.1 Example: Safety Housing for Composite Rotors of Stationary FESS
	8.4 Relevant Findings from Past Research Projects
		8.4.1 Particle Kinematics
	8.5 Practical Design of FESS Housings
	8.6 Analytical Calculation Methods for Designing FESS Burst Containments
		8.6.1 Calculation According to Lockheed Missiles Company [6]
		8.6.2 Calculation According to Giancarlo Genta [7]
		8.6.3 Calculation According to NASA [5]
	8.7 Application of the Calculation Methods and Comparison of the Results
		8.7.1 Summary and Plea for Empirical Burst Containment Studies
	8.8 Qualitative Analysis and Overview of Previous Burst Tests
	8.9 Empirical Investigation of FESS Burst Containments
		8.9.1 Commercially Available Spin Pits and Testing Services
		8.9.2 Structure of the Burst Test Bench
		8.9.3 Method and Experimental Procedure
		8.9.4 Energy Balance
		8.9.5 Summary of Previous Findings
	References
9: Bearings for Flywheel Energy Storage
	9.1 Analysis of Existing Systems and State of the Art
	9.2 Requirements Derived from the Supersystem Analysis
		9.2.1 Determination of Bearing Loads
	9.3 Gyroscopic Reaction Forces in Flywheel Energy Storage
		9.3.1 The Supersystem of FESS Bearings: Analysis of Environmental Parameters
		9.3.2 Influence of FESS-Specific Operating Conditions on Bearing Design
	9.4 Complexity and Importance of FESS Bearing Design
	9.5 Determination of Gyroscopic Bearing Loads
		9.5.1 Step 1: Analytical Estimation
			9.5.1.1 Results of the Analytical Assessment
		9.5.2 Step 2: Numerical Simulation
			9.5.2.1 Load Collective and Peak Values
			9.5.2.2 Estimation of Heavy Misuse Bearing Loads
			9.5.2.3 Results of the Numeric Simulation
		9.5.3 Step 3: Empirical Verification
			9.5.3.1 Results of the Empirical Verification
			9.5.3.2 Evaluation of the Empirical Verification
		9.5.4 Conclusion Regarding Gyroscopic FESS Bearing Loads
	9.6 Imbalance Forces in Energy Storage Flywheels
		9.6.1 Balancing and Balancing Options of the FIMD Rotor Case Study
			9.6.1.1 Problems of Subcritical Rotor Operation
			9.6.1.2 Estimation of the Natural Frequency of the FIMD Rotor Bearing System
			9.6.1.3 Influence of Bearing Stiffness on the Natural Frequency of the FIMD Rotor System
			9.6.1.4 Commissioning and Problems of FIMD Rotor Bearing System
			9.6.1.5 Analysis of the FIMD Rotor Bearing System
	9.7 Resilient Bearing Seats for Rolling Bearings in FESS
		9.7.1 Case Study CMO Flywheel Energy Storage System
		9.7.2 Investigation of Alternative Bearing Seat Concepts: Practical Example LESS
			9.7.2.1 Increasing Bearing Life Through the Use of Resilient Bearing Seats
			9.7.2.2 Summary: Bearing Loads in FESS
	9.8 Thermal Properties of FESS Bearings
		9.8.1 Test Rig for Determining the Thermal Conductivity of Rolling Bearings
	References
10: Stationary FESS for Modern Mobility
	10.1 Reduction of Torque Loss of FESS Bearings
		10.1.1 Bearing Concepts for Stationary Flywheel Energy Storage Systems
	10.2 Loads and Friction Losses in Rolling Bearings for FESS Applications
		10.2.1 Bearing Loads of Stationary Flywheel Energy Storage Systems
		10.2.2 Analytical Determination of Bearing Torque Loss
	10.3 Bearing Load Reduction for Energy Storage Flywheels with Roller Bearings
		10.3.1 Reduction of Axial Loads
			10.3.1.1 Option 1: Attracting Arrangement with Hard Ferrite Ring
			10.3.1.2 Option 2: Two Magnets in Repelling Arrangement
			10.3.1.3 Option 2b: Repelling Arrangement of Two SmCo Disk Magnets
	10.4 Reduction of Radial Bearing Loads
		10.4.1 Cast Silicone Bearing Seat
			10.4.1.1 Results
	10.5 FlyGrid: Flywheel Energy Storage for EV Fast Charging and Grid Integration
		10.5.1 Developments in Electric Mobility
		10.5.2 Aims of the FlyGrid Project
		10.5.3 Core Element Flywheel Energy Storage
	References
11: Summary and Outlook