A considerable part of the fuel energy in vehicles never reaches the wheels and entirely converts to waste heat. In a heavy duty vehicle (HDV), the heat power that escapes from the exhaust system may reach 170 kW. The waste heat can be converted into useful electrical power using a thermoelectric generator (TEG). During the last decades, many studies on the electrical power conditioning system of TEGs have been conducted. However, there is a lack of studies evaluating the electrical instrumentation, the impact of the converter efficiency, and the TEG arrangement on a real large-scale TEG on-board a drivable vehicle. In this paper, the most important parameters for designing electrical power conditioning systems for two TEGs, developed for a real-scale HDV as well as experimental results demonstrating the recovered electrical power, are presented. Eight synchronous interleaved step-down converters with 98% efficiency with a perturb and observe maximum power point tracker was developed and tested for this purpose. The power conditioning system was communicating with the on-board computers through the controller area network and reported the status of the TEGs and the recovered electrical power. The maximum recovered electrical power from the TEGs reached 1 kW which was transmitted to the electrical system of the vehicle, relieving the internal combustion engine.

/pdf/electrical-power-conditioning-system-for-thermoelectric-53vtssff3w.pdf

Electrical Power Conditioning System for Thermoelectric Waste Heat Recovery in Commercial Vehicles

The determination of the dynamic loading of the bearing structures of the main types of freight wagons with the actual dimensions under the main operating conditions is carried out. The inertial coefficients of the bearing structures of the wagons are determined by constructing their spatial models in the SolidWorks software package. Two cases of loading of the bearing structures of the wagons – in the vertical and longitudinal planes – have been taken into account. The studies were carried out in a flat coordinate system. When modeling the vertical loading of the bearing structures of wagons, it was taken into account that they move in the empty state with butt unevenness of the elastic-viscous track. The bearing structures of the wagons are supported by bogies of models 18-100. The solution of differential equations of motion was carried out by the Runge-Kutta method in the MathCad software package. When determining the longitudinal loading of the bearing structures of wagons, the calculation was made for the case of a shunting collision of wagons or a "jerk" (tank wagon). The accelerations acting on the bearing structures of the wagons are determined.
The research results will help to determine the possibility of extending the operation of the bearing structures of freight wagons that have exhausted their standard service life.
It has been established that the indicators of the dynamics of the load-carrying structures of freight wagons with the actual dimensions of the structural elements are within the permissible limits. So, for a gondola wagon, the vertical acceleration of the bearing structure is 4.87 m/s2, for a covered wagon – 5.5 m/s2, for a flat wagon – 5.8 m/s2, for a tank wagon – 4.25 m/s2, for a hopper wagon – 4.5 m/s2. The longitudinal acceleration acting on the bearing structure of a gondola wagon is 38.25 m/s2, for a covered wagon – 38.6 m/s2, for a flat wagon – 38.9 m/s2, for a tank wagon – 27.4 m/s2, for a hopper wagon – 38.5 m/s2. This makes it possible to develop a conceptual framework for restoring the effective functioning of outdated freight wagons.
The conducted research will be useful developments for clarifying the existing methods for extending the service life of the bearing structures of freight wagons that have exhausted their standard resource

/pdf/determination-of-dynamic-loading-of-bearing-structures-of-2illtzviz8.pdf

Determination of dynamic loading of bearing structures of freight wagons with actual dimensions

Motor drives is a widely used technology, offering many advantages, such as exceptional speed control and flexibility. Improvement of reliability and efficiency has become a great research interest. Toward this direction and considering the major recent developments in supercapacitor technology, the use of bidirectional energy recovery converters has been introduced in various industrial applications. In this paper, the regenerative braking of a three-phase induction motor controlled by a variable frequency drive will be analyzed and the portion of kinetic energy that can be recovered will be calculated. The main contribution of this paper is a methodology for the estimation of the energy savings that can be achieved from the use of such an energy recovery feature. In addition, the optimum braking duration that maximizes the recovered energy will be investigated. The analysis presented in this paper has been validated experimentally and the results are discussed.

Investigation of Energy Savings on Industrial Motor Drives Using Bidirectional Converters

To increase the reliability of aerospace electronics and reduce their overall power consumption, we investigated the possibility of incorporating active thermoelectric cooling (TEC) solutions. The harsh avionic environment demands sophisticated active control schemes that enable the achievement of high coefficient of performance. The positive effect of active PWM control has been validated both in simulation and on a working laboratory prototype that allowed us to clarify the pros and cons of the incorporation of TEC techniques in avionics applications. This paper has been performed under the framework of CLEAN SKY—THERMICOOL project.

Active Thermoelectric Cooling Solutions for Airspace Applications: the THERMICOOL Project

The objective of this paper is to present a power conversion system, based on a bidirectional DC/DC converter, along with a supercapacitor bank, that mitigates the voltage transients that occur on the DC distribution network of More/All Electric Aircrafts. These transients, such as voltage sags and swells appear on the DC buses of on-board microgrids, mainly due to load variations and are classified according to the aircrafts electric power system standards. First, we shortly describe an aircraft distribution network, that is applicable to the most common actual aircraft architectures, then we present the proposed system, along with the bidirectional DC/DC converter design, the control technique and the supercapacitor bank sizing. Finally, we present simulation and experimental results that support the effectiveness of the proposed system to effectively compensate voltage transients, supporting the DC buses in dynamic conditions. Concluding, the proposed system provides high power quality and compliance with the respective power quality standards for aircraft microgrids.

https://www.mdpi.com/1996-1073/13/16/4123/pdf

Voltage Transients Mitigation in the DC Distribution Network of More/All Electric Aircrafts

The efficiency of helicopters is limited due to the high power losses of combustion engines, a fraction of which can be recovered and provided to the electrical bus by exploiting the heat found in the exhaust gases and through power electronics converters. The first system recovers energy through a thermoelectric generator, whereas the second through a permanent magnet generator rotated by a steam turbine. A third power converter, connected to a supercapacitor bank, compensates the peak currents demanded by the loads. Since extensive simulations have to be run in order to validate the feasibility of those systems, average models of the power converters are derived, and their accuracy is examined. Finally, based on those average models, the developed control strategy is examined.

Modeling and analysis of an innovative waste heat recovery system for helicopters

Research in modern helicopters is targeted into the increase of their efficiency due to economical and ecological pressures. This paper introduces two innovative methods of absorbing a ratio of the energy remains of the main engine exhaust gases and converting it to electrical energy. The recovered power is then injected to the electrical bus of the helicopter through power electronics converters. The first one uses thermoelectric generators whereas the second one an electromechanical generator. Both of these systems are analyzed, candidate power converter configurations and topologies are depicted and the results of simulations using SABER are evaluated.

Innovative waste heat recovery systems in rotorcrafts

Common variable speed drives usually do not feature regenerative braking The energy produced during deceleration is dissipated through braking resistors In this paper, a bidirectional converter designed for use with variable speed drives, adding the capability of regenerative braking, is presented Hardware design and control algorithms are analyzed and comparison with similar proposals is made Finally, simulation verification and experimental results are presented

Analysis and design of a universal energy recovery converter for use with industrial inverters

Mechanical load simulators are useful in various cases, where we wish to test an electromechanical system. A mechanical load simulator can be used to emulate a wide variety of loads, such as industrial loads, electric vehicle drivetrain, etc. In this paper, a load simulator build for the testing of various electromotion systems, with the capability of four quadrant operation (positive or negative torque, positive or negative rotational speed) and very good transient behavior is presented. The four quadrant operation allows bidirectional power flow, thus enables the study of energy recovery braking. The overall system will be investigated, the control method will be analyzed and finally, simulation and experimental results will be presented.

http://ieeexplore.ieee.org/iel7/6611296/6631728/06634640.pdf

Ioannis Karatzaferis

Papers

Investigation of Energy Savings on Industrial Motor Drives Using Bidirectional Converters

Modeling and analysis of an innovative waste heat recovery system for helicopters

Innovative waste heat recovery systems in rotorcrafts

Analysis and design of a universal energy recovery converter for use with industrial inverters

Four-quadrant fully controlled mechanical load simulator