Non-Linear Input Impedance For Energy Harvesting Backpack
Open Access
- Author:
- Suffian, Stephen
- Area of Honors:
- Electrical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Heath Hofmann, Thesis Supervisor
Heath Hoffman, Thesis Supervisor
Dr. Timothy Joseph Kane, Thesis Honors Advisor
William Kenneth Jenkins, Thesis Honors Advisor - Keywords:
- SEPIC converters
energy harvesting - Abstract:
- The following paper investigates the efficiency of the power circuit of an energy harvesting backpack. The backpack is a spring-mass system that, with an 80 lb load, can generate over 10 Watts with normal walking gait. A 2 Hz, 5 cm, sinusoid was used for the physical excitation of the backpack in order to simulate typical walking. This mechanical energy is transferred through the spring-mass system to a brushless AC motor, which connects to a power conditioning circuit. This circuit allows for easy transfer of energy to batteries or other electronic loads. The following thesis analyzes the efficiency of the electrical circuit’s previously set 10 Ω emulated load, which is accomplished through current regulation in the input inductor of the circuit’s main SEPIC converter. It then seeks a more efficient, non-linear emulated load through theoretical analysis and empirical testing. Several piece-wise functions were experimentally tested to see if electrically disconnecting the power conditioning circuit at certain low voltages could improve backpack power output and efficiency. This thesis also shows experimental results for efficiency and power output of the non-linear load technique.