Design optimization of an energy harvesting platform for self-powered wireless devices in monitoring of ac power lines

This paper presents the design optimization of a magnetic field energy harvesting platform for self-powered ac power line monitoring devices in smart grid applications. The designed platform can be used with any type of vibration-to-electricity energy conversion schemes including piezoelectric, electromagnetic, and electrostatic energy harvesters. The platform includes a cantilever beam with a miniaturized permanent magnet (PM) at the tip that vibrates due to the interaction with the magnetic field of the ac line. The proposed method analytically determines the optimum geometric orientations of the platform as well as the optimum dimensions of PM to maximize the applied magnetic force to the beam. The validity of the design procedure and its assumptions are verified numerically and experimentally using a piezoelectric energy harvesting platform. The numerical and experimental test results confirm the calculated optimum orientation angles and PM dimensions that maximize the magnetic force. The analysis shows that for a PM with vibration direction in a plane normal to the power line, the maximum force can be achieved at the multiples of +45° with reference to the vibration direction. The optimum orientation angle also depends on the angles between the magnetization vector and the direction of the vibration.