System Analysis of a Suitable-Weighted-Pendulum Type Power Generator for TPMS

This paper presents the development of a passive natural frequency self-tuning power generator achieved using a suitably-weighted pendulum, which oscillates due to the periodic change of the tangent component of gravity to harvest kinetic energy from a rotating wheel. Furthermore, the nonlinear dynamic behavior of the weighted pendulum is discussed. By employing a suitably-designed weight, the natural frequency of the pendulum can be induced to match the rotating frequency of the wheel at any speed, and the pendulum oscillates at a large angle and velocity to generate a large amount of power in the simulations and experiments. Two kinds of magnetic circuit designs, multipolar magnetic segments and a Halbach-array type, are presented as an electromagnetic transformation mechanism. From the magnetic field simulation results, the Halbach-array type exhibits a high magnetic flux density for large power generation. In the experiments, at an optimum external resistance, the power output of the suitably-weighted pendulum with a multipolar magnetic circuit was approximately 200 to 300 micro-Watts at about 200 to 400 rpm. Power generation experiments for a weighted pendulum consisting of a Halbach-array magnetic circuit will be carried out in the future.