Ludek Janak

Modeling, simulation and experimental testing of the MEMS thermoelectric generators in wide range of operational conditions

The aim of this paper is to examine the performances of thermoelectric generator based on microelectromechanical systems technology (MEMS) in wide range of operational conditions. The goal is to evaluate capability of this technology for a development of an independent energy source for aircraft applications. Complex overview of MEMS TEG properties obtained by computational modeling, simulations and experimental testing is utilized to define critical phenomena of MEMS TEG technology.

Simulation Modelling of MEMS Thermoelectric Generators for Mechatronic Applications

This paper deals with an introduction to the simulation modelling of transient behaviour of MEMS thermoelectric generators (TEGs) for mechatronic applications. Special emphasis is put on the simulation of recently commercially achievable modules. At first is given the overview of prospective mechatronic applications of MEMS TEGs and the existing commercially achievable MEMS TEG modules are listed in a short trade review. Afterwards, the main features of thermoelectric energy conversion are described together with the simple governing equations. In the main part of paper is presented the simulation model for investigations of transient behaviour of MEMS TEG module. Derived model is implemented in MATLAB/Simulink Simscape. Results given by dynamic model are compared with results obtained by other modelling approaches and transient behaviour of MEMS TEG is evaluated.

Design of the charge push-through electronics for fully implantable artificial cochlea

The artificial cochlear implant is the only way how to get lost hearing back in some cases. Existing artificial cochlear devices use two separated parts for this purpose: a signal processing unit with transmitter and an implantable receiver with electrodes. This approach is applicable but not fully implantable. A new complex approach to design of a fully implantable artificial cochlea is described in this article. The proposed artificial cochlea consists of many subcircuits which have to be designed in close context to reach optimal performance and the lowest power consumption. Power consumption should be decreased to a value which allows using cochlear implant as a zero-powered system. A combination of micro-mechanized diaphragm filter bank, possible energy harvesting power source and especially ultra-low power processing electronics is presented in this article. A unique technique for nerve stimulatory output signal generation is discussed. This new technique named charge push-through electronics should use the major part of energy generated by energy harvesting subcircuit for output useful signal generation with minimal undesirable current. Mechanical parts of the subcircuits were simulated as complex electro-mechanical simulation models in ANSYS, CoventorWare, Matlab and SPICE environment. First, the real energy harvesting power source (human motion and temperature) behavior was measured. The model of this behavior was created in simulation environment and then the whole electronics simulation model for energy harvesting circuits was estimated. Next, signal processing circuits powered from energy harvesting power source were designed and simulated. The new signal processing circuits were simulated in relation to the results of complex electro mechanical diaphragm and SPICE energy harvesting power source simulation.

Energy harvesting for aerospace: Application possibilities

This paper deals with the state of art in the field of energy harvesting systems. The paper mainly aims to the novel field of energy harvesting systems utilized in aerospace environment. Their most prospective applications in zero-power sensors and backup power sources for low-power systems are outlined and discussed. Vibration and thermoelectric energy harvesters are presented as a most suitable alternative low-power sources for aerospace applications. Consequently, the system-level architecture of zero-power sensor and backup power source are described. Practical realization of energy harvesting systems for aerospace is shown on case studies of devices developed at the Brno University of Technology.

Simulation modelling of MEMS thermoelectric generator for aircraft applications

This paper deals with a simulation modelling of a thermoelectric energy harvester for aircraft applications. The aim of this paper is to provide overview of simulation modelling methods, which are used in development process of the autonomic thermoelectric energy harvester. The assumed harvester is based on MEMS technology and is capable to operate as an independent energy source under high range of operational condition required by aircraft applications.

Simulation of Power Management Electronics and Energy Storage Unit for MEMS Thermoelectric Generator

This chapter deals with a simulation modelling of the complex energy-harvesting unit based on MEMS thermoelectric generator. This chapter is mainly focused into the first steps in a development process—analysis of demands given on the aircraft-specific thermoelectric harvesting unit, choice of energy storage elements, conceptual architecture of power electronics and simulation of various operating states based on the typical operating envelope. The whole simulation modelling process is implemented in MATLAB/Simulink Simscape. Commercially available thermoelectric modules produced by Nextreme Thermal Solutions, Inc. are used as the sources of energy. The raw power output coming out of each of these modules is in the range of tens of milliwatts. Special attention is paid to the choice of energy storage unit. Designs using supercapacitors and batteries as the electric energy storage elements are considered and evaluated. Several architectures of electronics are examined through the simulation modelling. The presented model represents an important step in the process of a mechatronic design of the complex aircraft-specific thermoelectric energy-harvesting unit.

Modular Multidisciplinary Models for Prototyping Energy Harvesting Products

Energy harvesting systems provide an alternative solution to conventional energy sources by utilizing some form of energy from the ambient environment followed by its conversion to useful electric energy. Designing an efficient energy harvester requires prior knowledge and analysis of the conditions in the location of its intended installation. Therefore, an original energy harvesting solution is needed for every application. The development process of energy harvesters could be sped up by using modular fully parametric models of the system components. These models are developed from basic physical principles in such a way, that they can be freely combined into the multidisciplinary model of the system. The modules are intended to be used for the fast prototyping, comparison of different topologies and transducer types and for prediction of the possible output energy levels. The main motivation for a derivation of such models is their future implementation to the energy harvesting course for mechatronic engineering students. That will allow students to focus on the practical issues of designing an energy harvester for real-life applications using real input data instead of building, debugging and optimizing generic models of the energy harvesting transducers.

QUANTITIES AND SENSORS FOR MACHINE TOOL SPINDLE CONDITION MONITORING

The state-of-art machine tools incorporate a wide variety of sensors and associated signals that are used within the control system or as a process monitoring variables. Machine tool can also be equipped with additional sensors required by customer or manufacturer with relatively no limitation. Therefore, the key issue is in “separating the wheat from the chaff”. Only those data that can be linked to machine tool failures, unintended customers’ behaviour, or (exceeding) machine loading, are suitable for further implementation in machine tool condition monitoring system. This paper uses the methods formerly known from system safety and reliability analysis – namely Failure Modes and Effects Analyses (FMEA) and its Diagnostics extension (FMEDA) – to identify such data and physical quantities. The outlined approach is supported by a practical case study on machine tool spindle condition monitoring. The proposed spindle monitoring is based on noise intensity and indirect cutting force measurement.