High-Speed Kinetic Energy Buffer: Optimization of Composite Shell and Magnetic Bearings

Abrahamsson, Johan; Hedlund, Magnus; Kamf, Tobias; Bernhoff, Hans

doi:10.1109/tie.2013.2259782

Cited by 45 publications

(25 citation statements)

References 11 publications

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“…The final solution was then verified within the FEA software Solidworks, and the corresponding stresses and strains can be seen in Figure 1a. For the analytical equations, the steel was simulated as segmented by assuming a low E θ (similar in approach to [31]), and in FEA, it was done by simulating a 5 • segment, as seen in Figure 1c. The rotor is composed of four shells.…”

Section: Mechanical Simulation Resultsmentioning

confidence: 99%

“…On the other hand, the centrifugal forces within the composite rims increase with radius, causing tensile stress to build up, which can lead to delamination. Since the radial strength is much lower than the hoop strength for unidirectionally-wound composites, having steel on the inside can help keep the radial stress compressive (similar to [31]). The composite shells were press fitted.…”

Section: Mechanical Simulation Resultsmentioning

confidence: 99%

“…For a multi-shell situation, a system of equations is formed. These equations have been shown to work well for quickly solving for stress [31], allowing for iterative testing of different designs. The equations can be used to approximate stress for segmented inner shells by assuming a low E θ .…”

Section: Transversely Isotropic Materialsmentioning

confidence: 99%

“…To alleviate radial stress limitations, several thin composite shells are shrink-fitted onto each other. The shrink-fit process (and also the matrix curing process) limits how much interface pressure can be attained between shells, which in turn limits the maximal speed [31]. To account for this in the design below, thermal expansion limitations were accounted for when computing interference pressure.…”

Section: Practical Considerationsmentioning

confidence: 99%

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Reluctance Machine for a Hollow Cylinder Flywheel

Hedlund¹,

Kamf²,

Santiago³

et al. 2017

Energies

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A hollow cylinder flywheel rotor with a novel outer rotor switched reluctance machine (SRM) mounted on the interior rim is presented, with measurements, numerical analysis and analytical models. Practical experiences from the construction process are also discussed. The flywheel rotor does not have a shaft and spokes and is predicted to store 181 Wh/kg at ultimate tensile strength (UTS) according to simulations. The novel SRM is an axial flux machine, chosen due to its robustness and tolerance for high strain. The computed maximum tip speed of the motor at UTS is 1050 m/s. A small-scale proof-of-concept electric machine prototype has been constructed, and the machine inductance has been estimated from measurements of voltage and current and compared against results from analytical models and finite element analysis (FEA). The prototype measurements were used to simulate operation during maximal speed for a comparison towards other high-speed electric machines, in terms of tip speed and power. The mechanical design of the flywheel was performed with an analytical formulation assuming planar stress in concentric shells of orthotropic (unidirectionally circumferentially wound) carbon composites. The analytical approach was verified with 3D FEA in terms of stress and strain.

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Section: Mechanical Simulation Resultsmentioning

confidence: 99%

Section: Mechanical Simulation Resultsmentioning

confidence: 99%

Section: Transversely Isotropic Materialsmentioning

confidence: 99%

Section: Practical Considerationsmentioning

confidence: 99%

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Reluctance Machine for a Hollow Cylinder Flywheel

Hedlund¹,

Kamf²,

Santiago³

et al. 2017

Energies

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“…So far, three Ph.D. theses have been written within the flywheel subject. The main focus has been car drive line systems, but in later years, there has been some focus on other applications, as well, such as grid energy storage, wind power smoothing, cable ferries and larger vehicles, such as buses and garbage trucks [3,8,[58][59][60][61][62][63][64][65].…”

Section: Carsmentioning

confidence: 99%

Flywheel Energy Storage for Automotive Applications

et al. 2015

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A review of flywheel energy storage technology was made, with a special focus on the progress in automotive applications. We found that there are at least 26 university research groups and 27 companies contributing to flywheel technology development. Flywheels are seen to excel in high-power applications, placing them closer in functionality to supercapacitors than to batteries. Examples of flywheels optimized for vehicular applications were found with a specific power of 5.5 kW/kg and a specific energy of 3.5 Wh/kg. Another flywheel system had 3.15 kW/kg and 6.4 Wh/kg, which can be compared to a state-of-the-art supercapacitor vehicular system with 1.7 kW/kg and 2.3 Wh/kg, respectively. Flywheel energy storage is reaching maturity, with 500 flywheel power buffer systems being deployed for London buses (resulting in fuel savings of over 20%), 400 flywheels in operation for grid frequency regulation and many hundreds more installed for uninterruptible power supply (UPS) applications. The industry estimates the mass-production cost of a specific consumer-car flywheel system to be 2000 USD. For regular cars, this system has been shown to save 35% fuel in the U.S. Federal Test Procedure (FTP) drive cycle.

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