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Abstract:
The main drawback of vibration-based energy harvesting is its poor efficiency due to small amplitudes of vibration and low sensitivity at frequencies far from resonant frequency. The performance of electromagnetic energy harvester can be improved by using mechanical enhancements such as mechanical amplifiers or spring bumpers. The mechanical amplifiers increase range of movement and velocity, improving also significantly harvester efficiency for the same level of excitation. As a result of this amplitude of motion is much larger comparing to the size of the electromagnetic coil. This in turn imposes the need for modelling of electromagnetic circuit parameters as the function of the moving magnet displacement. Moreover, high velocities achieved by the moving magnet reveal nonlinear dynamics in the electromagnetic circuit of the energy harvester. Another source of nonlinearity is the collision effect between magnet and spring bumpers. It has been shown that this effect should be carefully considered during design process of the energy harvesting device. The present paper investigates the influence of the above-mentioned nonlinearities on power level generated by the energy harvester. A rigorous model of the electromagnetic circuit, derived with aid of the Hamilton's principle of the least action, has been proposed. It includes inductance of the electromagnetic coil as the function of the moving magnet position. Additionally, nonlinear behaviour of the overall electromagnetic device has been tested numerically for the case of energy harvester attached to the quarter car model moving on random road profiles. Such a source of excitation provides wide band of excitation frequencies, which occur in variety of real-life applications.

Keywords:
energy harvesting, velocity amplification, nonlinear electromagnetic circuit, spring bumper, quarter car model

Abstract:
A method for a sizing of an electromechanical battery for electrical go-kart was presented in the paper. The main goal of this research was to replace the internal combustion (IC) engine by an electric drive system taking into account the traction properties, on the one hand and the duration of operation on a single charge and the number of the battery life cycles on the other. The proposed method permits an entire depreciation of the price of the vehicle before the degradation of the battery occurs. The results of the study have been used to adjust the source for electric go-karts that will be mass produced.

Keywords:
electrical vehicle, go-kart, optimal battery sizing, traction simulation