Design and optimization of a biomechanical energy harvesting device

This paper addresses a design and optimization procedure of a biomechanical energy conversion system. First, the center-of-mass motion is identified as an energetic motion. Based on the characteristics of the motion, a linear permanent magnet generator topology is proposed. Magnetic equivalent circuits are developed for the linear generator, which are then used to optimize for the maximum-power output. A maximum-power extraction circuit is proposed as the interface between the generator and battery load. The circuit functions as a matched resistor to the generator internal resistance. A test generator is built and tested with impedance-matching circuit. Average power of 90 mW to 780 mW was measured for different walking conditions for a 1-kg swing weight.