Energy Harvesting

Dynamics and Vibrations Group

Vibration-based energy harvesting

wobbling disk energy harvester
wobbling disk energy harvester

In the past decade energy harvesting has received great attention from researchers of different disciplines, including mechanical and electrical engineering, as well as researchers from the field of material science. Research motivation in this field is to power small electronic devices using the energy from their environment in order to make an external power source or periodic battery replacement redundant or at least to minimize it. Such energy harvesting systems cover a wide range of applications, for example self-powered sensors in automobile applications, wireless sensor nodes for structural health monitoring in aircraft or many other applications in civil or mechanical engineering.

Structural vibrations or motions represent besides the other types of ambient sources of energy (thermal, solar, etc.) the most commonly available one, with a significant amount of energy. For the conversion of mechanical into electrical energy, the three basic mechanisms are electrostatics, electromagnetism and piezoelectricity. Wherein, for a vibration-based energy source, the piezoelectric mechanism is the one with a relatively high coupling coefficient as well as high power densities. This research area is called vibration-based piezoelectric energy harvesting and is divided in two main research topics. The first one deals with the design and optimization of suitable electromechanical devices for the conversion of ambient motions into useable strain applied on the piezoelement. The second one deals with the architecture of the electrical network for the management of the converted energy.

The primary problem of the current energy harvesters is their narrow bandwidth. There is a significant drop in produced power levels for small deviations from the resonance frequency. Therefore, the idea is to exploit nonlinear techniques to increase the overall efficiency of energy harvesting devices, so that they can harvest power across varying vibration inputs.

In the Dynamics and Vibrations Group the idea of using self-excitation mechanism for energy harvesting is investigated. The main advantage of these applications is that the motion of the excited system is almost independent of the type or frequency of the excitation signal. This approach promises to extend the applicability and the overall efficiency of energy harvesting systems. The research involves both theoretical modeling and experimental investigations of systems exploiting self-excitation mechanisms for energy harvesting. Currently treated topics are:

  • modeling of self-excitation mechanisms
  • stability and bifurcation analysis
  • design and experimental investigation of ultrasonic generators

Students who are interested in writing a thesis, a seminar paper or in doing an advanced design project about these topics, should not hesitate to contact one of the members of the group or Prof. Peter Hagedorn directly.