Design and control of battery charger for portable human powered generator

The developmental process and the battery charging strategy of 100W battery charging circuits using a three-phase permanent magnet synchronous generator are presented. It is assumed that a typical male can comfortably generate over 100W using cranking motions with two feet. Using a portable and manual generator, human cranking motions are converted to three-phase ac electric power, and the electric power is efficiently harvested and stored in a battery pack using a battery charging circuit consists of a three-phase boost rectifier and a buck converter. The boost rectifier utilizes a mechanical sensorless method to estimate the generator´s rotor position to reduce size and increase reliability. The overall development processes that include topology selection, parameter selection criteria, battery charging strategy with controller gain values, and experimental results, are presented. The experimental results demonstrate the battery charging capability over 100W using a sensorless algorithm.